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Attentional Profile of Childhood Autism Spectrum Disorder: Is It Different from That Seen in ADHD?

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Attentional Profile of Childhood Autism Spectrum Disorder: Is It Different from That Seen in ADHD?
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2008

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Asperger syndrome ( jstor )
Attention deficit hyperactivity disorder ( jstor )
Autistic disorder ( jstor )
Business executives ( jstor )
Child psychology ( jstor )
Hyperactivity ( jstor )
Intelligence quotient ( jstor )
Parents ( jstor )
Selective attention ( jstor )
Standard deviation ( jstor )

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University of Florida
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ATTENTIONAL PROFILE OF CHILDHO OD AUTISM SPECTRUM DISORDER: IS IT DIFFERENT FROM THAT SEEN IN ATTENTION DEFICIT HYPERACTIVITY DISORDER? By CARA I. KIMBERG A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2006

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Copyright 2006 by Cara I. Kimberg

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iii ACKNOWLEDGMENTS I thank Shelley C. Heaton, Ph.D., for he r invaluable mentorship and guidance throughout this project. I also thank Gregory Valcante, Ph.D., for his enthusiasm and help with the recruitment phase of this projec t. Finally, I thank my parents, Bernie and Judi, and my brother, Daniel, for their encouragement and support.

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iv TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iii LIST OF TABLES.............................................................................................................vi ABSTRACT......................................................................................................................v ii CHAPTER 1 INTRODUCTION........................................................................................................1 Sustained Attention.......................................................................................................3 Selective Attention........................................................................................................4 Attentional Control.......................................................................................................4 Divided Attention.........................................................................................................6 Behavioral Ratings........................................................................................................7 Aims of the Current Study............................................................................................7 2 METHODS...................................................................................................................9 Participants................................................................................................................... 9 Autism Spectrum Disorder Group (ASD).............................................................9 Attention Deficit Hyperactiv ity Disorder Group (ADHD).................................10 Procedures...................................................................................................................11 Attentional Tests..................................................................................................11 Parent-report Behavioral Measures.....................................................................12 3 RESULTS...................................................................................................................14 Sustained Attention.....................................................................................................17 Selective Attention......................................................................................................17 Attentional Control.....................................................................................................17 Divided Attention.......................................................................................................17 ConnersÂ’ Parent Rating Scale.....................................................................................18 Follow-up Analyses: Comparison of ASD to the ADHD Subtypes...........................20 4 DISCUSSION.............................................................................................................26 Sustained Attention.....................................................................................................26

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v Selective Attention......................................................................................................28 Attentional Control.....................................................................................................28 Divided Attention.......................................................................................................31 Parent Ratings of Behavior.........................................................................................32 Follow-up Analyses: ASD compared to ADHD Subtypes.........................................33 Limitations and Streng ths of Current Study...............................................................33 Future Directions........................................................................................................34 LIST OF REFERENCES...................................................................................................36 BIOGRAPHICAL SKETCH.............................................................................................41

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vi LIST OF TABLES Table page 1 Group Means and Standard Deviations for Age and IQ..........................................14 2 Means (and Standard Deviations) on Attention Measures: ASD vs. ADHD...........16 3 Means (and Standard Deviations) on the ConnersÂ’ Parent Rating Scale.................19 4 Group Means and Standard Deviations for Age and IQ: ASD vs. ADHD subtypes....................................................................................................................21 5 Means (and Standard Deviations) on Attention Measures: ASD vs. ADHD subtypes....................................................................................................................23 6 Group Differences on Parent Ratings of Behavior: Means (and Standard Deviations)1..............................................................................................................25

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vii Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science ATTENTIONAL PROFILE OF CHILDHOOD AUTISM SPECTRUM DISORDER: IS IT DIFFERENT FROM THAT SEEN IN ATTENTION DEFICIT HYPERACTIVITY DISORDER? By Cara I. Kimberg May 2006 Chair: Shelley C. Heaton Major Department: Clini cal and Health Psychology Children with Autism Spectrum Disorders (ASD) can display attentional difficulties that appear somewhat similar to those seen in Attention Deficit Hyperactivity Disorder (ADHD). However, the DSM-IV spec ifies that a comorb id diagnosis of ADHD is only warranted if the attentional deficits occur outside the normal course of ASD. Unfortunately, limited research has been conducted to determin e the expected attentional profile in ASD and few studies have directly compared children with ASD to those with ADHD. As such, clinicians can find it difficult to determine if attentional problems displayed in a child with ASD warrant a comorbid diagnosis of ADHD. The current pilot study utilizes a multid imensional model to examine attentional profiles of un-medicated boys, ages 6-16, car rying a diagnosis of ASD (without ADHD; n=10) to those diagnosed with ADHD (n=16) . Attentional performance was examined across selective, sustained and attentional cont rol composite scores derived from the Test of Everyday Attention for Child ren (TEA-Ch) and the Conner sÂ’ Continuous Performance

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viii Test (CPT) as well as two di vided attention tasks from th e TEA-Ch. Parent ratings on six key scales of the ConnersÂ’ Parent Rating Scale (CPRS-R:L) were also examined. Qualitative examination of the ASD group profile revealed performance within normal limits across all three attentional domai ns (including the CPT) and one of the two divided attention tasks. Gr oup comparisons revealed th at the ASD group performed significantly better on the atte ntional control composite an d significantly worse on the divided attention task involving simultane ous auditory-visual processing. Although parents rated both groups as displaying similar levels of hyperactivity, the ASD group was rated as having fewer inattentive be haviors and more social problems and perfectionist behavior. Follow-up analyses ex plored potential group differences when ADHD was further broken into subtype grou ps. Results are discussed in terms of diagnostic challenges and future directions.

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1 CHAPTER 1 INTRODUCTION Attention, broadly defined, is a cognitive domain that has been noted to be impaired within a variety of childhood deve lopmental, psychiatric, and neurological conditions. Conceptualized as a multidimen sional construct, many of the proposed models of attention suggest that it can be divided into four main processes: sustained attention, selective atte ntion, attentional contro l, and divided atten tion (Cooley & Morris, 1990; Mirsky, Anthony, Duncan, Ahearn, & Ke llam, 1991; Sergeant & Van der Meere, 1990). While the construct of attention has b een studied in children with developmental disorders, examination of more specific at tentional domains may help to identify risk factors, the presence of true comorbid diagno ses, as well as potential treatments for particular clinical populations (Goldberg et al., 2005). The current study utilizes a multidimensional framework of attention to examin e the specificity of deficits in children with two diagnostically distinct developmental disorders. Autism Spectrum Disorders (ASD) and Atte ntion Deficit Hyperactivity Disorder (ADHD) are developmental disorders with ve ry different diagnostic features. More specifically, ASD is characterized by impairments in social interaction and communication, and the presence of repetitive, restricted a nd stereotyped patterns of behavior (American Psychiatric Association, 1994). In contrast, ADHD is characterized by developmentally inappropriate levels of inattention, hyperactiv ity and impulsivity (American Psychiatric Associat ion, 1994), with less impacted social skills. While the key diagnostic features of ASD and ADHD have prominent differences, both groups have

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2 been noted to display attentional problems. In fact, some researchers believe that these similar attentional deficits may refl ect a shared underlying mechanism. Neuroanatomical, neurochemical and geneti c links have been used to explain similarities between ASD and ADHD. Both ar e disorders of the fr onto-striatal pathway and accordingly display behavior similar to that of patients with frontal lobe damage (Geurts, Verte, Oosterlaan, & Roeyers 2004). With respect to neurochemistry, ASD and ADHD are hypothesized to have analogous abnormal levels of dopamine. This theory is supported by the effectiveness of psychostim ulant medication in managing symptoms of inattention and hyperactivity in both popul ations (Fein, Dixon, Paul, & Levin, 2005; Handen, Johnson & Lubetsky, 2000). In fact, Kinsbourne (1991) proposed a theoretical model, which describes both ASD and ADHD as having unstable arousal systems that lie on a continuum of arousal and stimulus s eeking, spanning from children with ADHD to healthy control children to over-focused childr en with ASD. This model, which links behavioral features of ASD to ADHD, supports the speculation that va riations in a gene on chromosome 16p13 may contribute to comm on neurobehavioral impairments found in both disorders (Smally et al., 2002). While theoretical models and neuroscience research have suggested a link between the attentional deficits seen in ASD and ADHD, diagnostic guidelines seem to be somewhat in opposition to this view. More specifically, accordi ng to the DSM-IV, a child diagnosed with ASD cannot receive a comorbid diagnosis of ADHD if the symptoms of inattention and hyperactivity “o ccur exclusively duri ng the course of a pervasive developmental disorder” (Ame rican Psychiatric A ssociation, 1994). Researchers have argued about the benefit of this exclusionary criterion (Goldstein &

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3 Schwebach, 2004) and clinicians have expresse d the difficulty in determining whether the inattentive and hyperactive behavior often displayed by children with ASD extend beyond the core expected features (Handen, Johnson, & Lubetsky, 2000; Goldstein & Schwebach, 2004). Therefore, despite the DSM-IV providing ex plicit criteria necessary for a comorbid diagnosis of ASD and ADHD, the scarcity of re search regarding the pa ttern of attentional performance in ASD makes it difficult to concep tualize the expected impairments for this population. Furthermore, res earch that has been conducte d has not accounted for the multidimensional nature of attention, limiting our understanding of the specific attentional skills in ASD. The sections that follow summarize the existing literature regarding the attentional performances of ASD and ADHD across components of attention and parent ra tings of behavior. Sustained Attention Sustained attention is defined as the abil ity to maintain attention over an extended period of time (Manly, Robertson, A nderson & Nimmo-Smith, 1999). Continuous Performance Tasks (CPTs) are a popular met hod of measuring sustained attention. The CPT structure can vary across a number of di mensions, but all models ultimately measure vigilance (Conners, 2000). It is generally accepted that children diagnosed with ADHD demonstrate impaired performance on tasks of sustained attention, as demonstrated by inhibition deficits (Barkley, Grodzinsky, & DuPaul, 1992). In fact, CPTs are often used to aid in the diagnosis of ADHD. The literature regarding th e sustained attention skills of children with ASD is less definitive. Some st udies have determined that individuals with ASD do not differ from healthy controls, whil e other studies suggest that even if the overall performance on tasks of sustained atte ntion is not discrepant , children with ASD

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4 may process the stimuli differently (Siege l, Nuechterlein, Abel, Wu, & Buchsbaum, 1995; Goldstein, Johnson, & Minshew, 2001). Qualitatively, children with ASD are often described as displaying enhanced sustai ned attention; this is demonstrated through their tendency to engage in repetitive ac tivities (Goldstein, Johnson, & Minshew, 2001) or to focus on a particular aspect of the environment (Pascualvaca, Fantie, Papageorgious, & Mirsky, 1998). Selective Attention Selective attention is defined as the abil ity to select target information from an array of distracters (Manly et al., 1999). A person must attend to designated relevant stimuli while ignoring extraneous component s. Children with ADHD are generally found to have normal performance on tasks measuri ng selective attention (Heaton et al., 2001; Hooks, Milich, & Lorch, 1994; Manly et al., 1999). In fact, researchers have determined that children with ADHD are only impaired on tasks of selective attention with high encoding demands (Heaton et al., 2001) . The literature regarding the selective attention skills of children w ith ASD is again inconsistent. Some studies suggest that children with ASD are more susceptible to the presence of distracters when compared to control children (Burak, 1994), while other researchers have not found this deficit (Noterdaeme, Amorosa, Mildenberger, S itter, & Minow, 2001). It has also been suggested that individuals with ASD ma y utilize a compensatory mechanism when selectively processing information (Belmonte & Yurgelun-Todd, 2003). Attentional Control Attentional control (which is also someti mes referred to as attentional shift or attentional flexibility) is defined as the abi lity to shift attention adaptively and flexibly (Manly et al., 1999). Sometimes attentional co ntrol is inaccurately used interchangeably

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5 with the term executive function. In fact , executive function in and of itself is a multidimensional construct that consists of the following domains: inhibit, shift, emotional control, initiate, working memor y, plan/organize and monitor (Gioia, Isquith, Guy, & Kenworthy, 2000). Attentional control is closely related to only two of these executive function components: set-shifting and inhibition. However, much like its construct, tasks used to measure executive function (and therefor e stated to measure attentional control) apply multiple cognitive co mponents. Therefore, in order to get a true measure of attentional control, task s that selectively measure set-shifting and inhibition must be used. Despite this knowledge, many researchers have globally hypothesized that ASD and ADHD are disorder s of executive function (and therefore attentional control), leading to an explosion of research in this broad area. The Wisconsin Card Sorting Task (WCST) (Heaton, 1981) is a common measure of executive function. It involves the ability to form abstract concepts, to sustain attention, and to shift cognitive sets flexibly in response to vary ing conceptual rules, while simultaneously inhibiting incorrect responses (Tsuchiya, Oki, Yahara, & Fujieda, 2005). Both individuals with ADHD and AS D have been found to perf orm poorer than control children on a number of indices of the WCST (T suchiya et al., 2005). Tasks such as this, that employ multiple cognitive processes, limit the evaluation of the distinct aspects of executive function. Recently, researchers have begun to administer multiple tasks, each representing a particular component of ex ecutive function, in an attempt to capture performance on the specific aspects of this multidimensional construct. It is generally thought that children with ASD are impair ed on tasks of set-shifting (Ozonoff et al., 2004; Pascualvaca et al., 1998, Lopez, Lincoln, Ozonoff, & Lai, 2005)

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6 while children with ADHD are impaired on tasks of inhibition (Geurts et al, 2004; Ozonoff & Jensen, 1999). However, these finding s have not been consistently replicated (Goldberg et al., 2005). One explanation for the mixed findings in children with ASD is related to the different task paradigms used across studies. More specifically, Pascualvaca and colleagues (1998) noted that children with ASD were able to shift their attention from one activity to another except in ci rcumstances where they had been allowed sufficient time to become “stuck” in a current activity. This suggests that set-shifting abilities for children with ASD are dependent on how involved they are in a task when they are requested to shift focus. These inconsistencies suggest that studies examining attentional control must utilize tasks that specifically target set-shifting and inhibition abilities, rather than using tests of broader executive function (Geu rts et al., 2004; Heaton et al., 2001). Divided Attention Divided attention is defined as the ability to focus on all simultaneously occurring pertinent stimuli (Manly et al., 1999). Th e literature regardi ng the performance of children with ASD and children with ADHD on tasks of divided attention is quite limited. However, it has been suggested that children with ADHD do not perform significantly poorer than clinical control child ren on tasks measuring divided attention. This finding remains true both within and between sensory modalities (Heaton et al., 2001). In fact, some research suggests that children with ADH D make significantly fewer errors than typical control participan ts on tasks of divide d attention (Koschack, Kunert, Derichs, Weniger, & Irle, 2003). On the other hand, individuals diagnosed with ASD have been found to have a deficit in di viding attention between auditory and visual sensory modalities (Belmonte & Yurgelun-Todd , 2003; Courchesne et al., 1994). More

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7 specifically, a study of the attentional skills of autistic savants determined that these individuals were unable to e ffectively divide their atten tion when required to detect simultaneous visual and auditory target s (Casey, Gordon, Mannheim, & Rumsey, 1993). Behavioral Ratings In clinical settings, parent ratings are c onsidered to be useful, although subjective, tools in assessing behavior. Of ten a childÂ’s behavior will be environment-dependent and a structured research setting, in which the child is receiving one-on-one attention, is considered optimal. Parent ratings allow the evaluator to conceptualize the daily behavior of a child, as well as understand the childÂ’s typica l level of functioning. Thus, in order to receive a diagnosis of ADHD, a child must be rated as displaying inappropriate levels of hyperactivity and inattention across multiple environments (American Psychiatric Association, 2004) . The DSM-IV does not require this for a diagnosis of ASD. The literature suggests that children with ADHD cannot be differentiated from children with ASD on scales of parent questi onnaires that focus on ex ternalizing behavior (i.e. hyperactivity). However, the groups ar e distinguishable on i ndices that measure internalizing behavior (i.e. inattention) a nd peer relatedness (i.e. social interaction) (Jensen, Larrieu, & Mack, 1997; Luteij n, Jackson, Volkmar, & Mindera, 2000). Aims of the Current Study The primary goals of the current study are to use a clinical assessment battery to learn more about the specificity of attentio nal deficits in children with ASD and to compare this profile of ASD a ttentional performance to children with ADHD. It is often difficult to determine if the symptoms of hypera ctivity and inattention that are frequently displayed in children with ASD extend beyond th at which is expected for this population, thereby warranting a comorbid diagnosis of ADHD. As such, the present study aims to

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8 establish if ASD and ADHD can be systemati cally differentiated from one another in terms of attentional strengths and weaknesse s on a multidimensional test of attention, and whether the groups can be additionally di scriminated based upon parent ratings of identified key diagnos tic behaviors. Based on the literature and anecdotal obs ervations, we hypothesize that the ASD group will display attentional weaknesses on the domain of at tentional contro l and on the divided attention task that utilizes two se nsory modalities. When the ASD attentional profile is compared to the ADHD group we ex pect to find significant group differences on the domain of sustained attention, with the ASD group performing significantly better, and on the divided attention task that utilizes two sensory modalities, with the ASD group performing significantly worse. With resp ect to parent ratings of behavior, we hypothesize that there will be significant group differences on the scales measuring perfectionism, social problem, and inattenti on, with the ASD group being rated as having significantly more perfectionist behavior and displaying significantly more social problems. On the other hand, we predict that the ASD gr oup will be rated as having significantly fewer inattentive behaviors.

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9 CHAPTER 2 METHODS Participants A total of 26 un-medicated boys between the ages of 6 and 15-years-old participated in this study: 16 diagnosed with ADHD and 10 diagnosed with ASD. The majority of participants were Caucasia n. Within the ADHD group, 14 were Caucasian, one was Hispanic and one was of mixed ethnicity. Within the ASD group, 8 were Caucasian, one was Hispanic and the remain ing participant was of mixed ethnicity. Participants were excluded if their intellectual functioning was determined to be in the mentally retarded range (FSIQ scores less th an 70 on the Wechsler Intelligence Scale for Children-Third Edition, WISC-III, or the We chsler Abbreviated Scale of Intelligence, WASI), if they had a prior head injury or history of a neurological condition (e.g. seizure disorder). Autism Spectrum Disorder Group (ASD) The ASD group was recruited through th e Center for Autism and Related Disabilities (CARD). All ch ildren had previously been diagnosed with an ASD (two children diagnosed with Aspe rgerÂ’s Disorder, two children diagnosed with Autism and six children diagnosed with High Functioning Autism). Diagnoses were confirmed using the Childhood Autism Rating Scale (CARS) (S chopler, Reichler, & Renner, 1988), which was completed using a semi-structured interv iew with the parent(s ) and observations of the childÂ’s behavior throughout the assessment visit.

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10 Children with ASD were excluded from the study if they had ever received a formal diagnosis of ADHD from a psychol ogist or pediatrician. Ch ildren were also excluded from the study if they were taking psychos timulant medication, even if they had not received a formal diagnosis of ADHD (one child was excluded). Finally, data was excluded from analyses if the child was unable to complete 4 or more subtests of the primary neuropsychological test measure (one childÂ’s data was ex cluded for this reason and was not included in the sample size). The ChildrenÂ’s Interview for Psychiatric Syndromes Parent Version (P-ChIPS) (Weller, Weller, Fristad, Rooney, & Weller, 19 99) was used to scre en for presence of generalized anxiety disorder, depression or oppo sitional defiant disorder. No children in this sample met diagnostic criter ia for any of these disorders. Attention Deficit Hyperactivity Disorder Group (ADHD) Children with ADHD were recruited from the Psychology and Psychiatry Clinics at Shands Hospital at the Univ ersity of Florida and through community advertisements. The diagnosis of ADHD was confirmed using the P-ChIPS (Weller et al., 1999). The PChIPS was also used to c onfirm ADHD subtype classifica tion. Eight of the sixteen children met diagnostic criter ia for the Combined Inatte ntive-Hyperactive/Impulsive subtype (ADHD-C). The remaining eight ch ildren with ADHD met criteria for the Predominantly Inattentive (ADHD-I) subtype. None of the children in the ADHD group had received a previous diagnos is of an ASD; however, this was not specifically screened for at the time of testing. Ten of the sixteen children with ADHD in this sample were reported to typically take stimulant medication. For the children who normally took psychostimulants, none took medication the day of testing. The P-ChIPS was also used to screen for generalized anxiety disorder, de pression, and oppositional defiant disorder and

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11 children were excluded if they met criteria for any of these diagnoses (20 children were excluded). Additionally, children were exclude d if they were unable to complete 4 or more subtests of the primary neuropsychol ogical test measure (22 children were excluded). Procedures Attentional Tests Four attentional domains were evaluated in the current study: sustained attention, selective attention, attentiona l control, and divided attent ion. All study participants completed the nine subtests from the Test of Everyday Attention for Children (TEA-Ch; Manly, Robertson, Anderson, & Nimmo-Smith , 1999) and the computerized ConnersÂ’ Continuous Performance Tests (CPT & CPT-II ; Conners, 1995). Scores from these tests were then used to represent each of the four attentional domains. Raw scores from the TEA-Ch subtests and the CPT were transformed into age-and gender-adjusted standardized scores. TEA-Ch s ubtests yield scaled scores, with a scale mean of 10 and standard deviation of + 3, such that scores be low 7 reflect attentional impairment. The CPT yields a variety of pe rformance indices. However, for the purpose of this study, the composite Overall Index Sc ore was used to reflect global performance on the CPT. Values above nine are indicative of attentional impairmen t. For the current study, a small proportion of the ADHD group (n = 4) completed the earlier version of the CPT, while all other participants were given the CPT-II. The nine TEA-Ch tasks are distributed across the attentional domains, while a composite score from the CPT is classified only within the sustaine d attention domain. It is important to note that the nine TEA-Ch tasks were not arbitrarily assigned to an attentional domain. Rather, th e results of the normative samp le factor analysis published

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12 by the test authors was used to assign TEA -Ch tasks to a give n attentional domain (Manly et al., 1999). The ex ception to this method was in placing two of the TEA-Ch tasks into the divided attention domain. The f actor analytic study indicated that the two divided attention tasks best grouped with the other three sustained attention tasks. However, this analysis is notably conducted on a normative sample, and may not reflect distribution of tasks within a clinical sample. In fact, results of an ear lier study of the TEA-Ch in an ADHD sample suggested that children with ADHD did not perform in the same manner on the two divided attention tasks as they did on the other three TEA-Ch tasks of sustained attention (Heaton et al., 2001). This prior finding, coupled with the current studyÂ’s interest in divided attention, led to these two ta sks being extracted and exam ined as divided attention. To reduce the overall number of attentiona l variables, scaled scores from TEA-Ch subtests within each attentional domain were collapsed into a single composite score for the given domain. For example, for each particip ant, scaled scores from the two selective attention tasks were summed and divided by two, yielding a single composite selective attention scaled score. For the two divided attention tasks we purposefully did not create a composite because we anticipa ted that children would perf orm differently on these two tasks. More specifically, we believed that performance would vary across the divided attention tasks because one task utilized tw o sensory modalities while the other used only one sensory modality. Parent-report Behavioral Measures The ConnersÂ’ Parent Rating Scale-Revise d: Long Version (CPRS-R:L) (Conners, 1997) is a behavior rating scale designed to assess the presence of ADHD in children and adolescents. While this questionnaire yiel ds 14 behavioral scal es, the current study

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13 focuses on six scales: Cognitive Problems/In attention, Hyperactivity, Perfectionism, Social Problems, DSM-IV: Inattentive, and DSM-IV: Hyperactive-Impulsive.

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14 CHAPTER 3 RESULTS Table 1 presents means (and standard deviations) for each group of participants for chronological age, Full Scale IQ (FSIQ), Perf ormance IQ (PIQ), and Verbal IQ (VIQ). A t-test revealed that the groups were comparab le in terms of age at the time of assessment (t (24) = 1.43, p = .166). Chi square analys is similarly revealed th at the two groups were comparable in terms of ethni city, with approximately 80% Caucasian in both groups ( X2 (2, N = 26) = 30.77, p = 0.00). T-tests were al so conducted on the IQ scales (FSIQ, PIQ, VIQ). Results were significant for FSIQ (t (24) = 3.099, p = .005) and PIQ (t (24) = 3.361, p = .003), while VIQ was comparable for the two groups (t (24) = 1.963, p = .062). Children with ASD had significantly higher FSIQs , and PIQs compared to children with ADHD. Table 1: Group Means and Standa rd Deviations for Age and IQ ASD ADHD p -value ( N = 10) ( N = 16) Chronological Age (CA) 8.70 (3.56) 10.62 (3.19) 0.166 Full Scale IQ (FSIQ) 110.40 (13.79) 93.88 (12.88) 0.005 Performance IQ (PIQ) 116.20 (19.57) 95.75 (11.60) 0.003 Verbal IQ (VIQ) 105.56 (16.11) 93.31 (14.32) 0.062 Analyses were conducted both with and without including IQ as a covariate because the controversy of using IQ as a c ovariate when analyzing data from children with psychiatric disorders has not yet been resolved (Willcut et al., 2001 in Goldberg et al, 2005). There were no significant inte ractions between group and IQ for any experimental measure (all p s > 0.304), permitting the use a single covariate, FSIQ, in all

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15 analyses. The use of FSIQ as the covariate was further supported by the necessity for the utilization of both language and perception skil ls in all tasks administered (Goldberg et al., 2005). We used multiple ANCOVAs to compare groups on the dependent measures for each factor of attention. Composite scores were considered to be the dependent measure for the domains of sustained attention, sele ctive attention and at tentional control. Standard scores were used as the dependent measure for the two divi ded attention tasks. Index scores were the dependent measure fo r the continuous perfor mance task. Table 2 illustrates group means and standard devi ations for the attention tasks.

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16Table 2: Means (and Standard Deviati ons) on Attention Measures: ASD vs. ADHD Attentional Domain ASD ADHD p -value Effect (N = 10) (N = 16) size Sustained Attention TEA-Ch composite Scaled Score 8.716 7.00 0.508 0.576 (2.62) (3.36) CPT-II overall index score 5.26a 8.60 0.404 0.369 (8.44) (9.91) Selective Attention TEA-Ch composite Scaled Score 8.70 8.78 0.967 0.034 (3.14) (1.94) Attentional Control TEA-Ch composite Scaled score 8.95 5.47 0.008 1.282 (2.87) (2.80) Divided Attention TEA-Ch subtest(auditory-audito ry) 7.70 7.19 0.863 0.131 (3.80) (4.20) TEA-Ch subtest(auditory -visual) 6.44a 7.94 0.036 0.475 (4.25) (2.65) a n = 9

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17 Sustained Attention There were no differences be tween groups in th e domain of sustained attention as measured by the TEA-Ch (F (1,24) = .453, p = .508) or on the Overall Index score of the Continuous Performance Tasks (F (1,23) = .723, p = .404). The results remained consistent whether or not FSIQ was controlled. Altho ugh there was no statistically significant difference, examination of group means revealed that the ADHD group performed within the impaired range on the domai n of sustained attention as measured by the TEA-Ch, while the ASD group perf ormed within normal limits. Selective Attention An ANCOVA on the domain of selective at tention as measured by the composite score of the TEA-Ch indicated no si gnificant between group difference (F (1,24) = .002, p = .967). The results rev ealed the same conclusion when FSIQ was not included in the analysis. Clinically, both groups fell within normal limits. Attentional Control As displayed in Table 2, children with ASD performed signifi cantly better on the attentional control domain compar ed to children with ADHD (F (1, 24) = 8.33, p = .008). This remained constant whether or not FSI Q was used as a covariate. Qualitative examination of group scores confirmed that children with ASD performed within normal limits on the attentional control factor while children with ADHD fell within the clinically impaired range. Divided Attention ANCOVAs on the two divided attenti on subtests in th e TEA-Ch revealed clinically dichotomous results. On the divide d attention task that required simultaneous auditory-auditory processing, children with ASD performed within normal limits while

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18 children with ADHD performed in the impaired range. Statistically this difference was not significant. In contrast, on the divided attention task that utilized simultaneous auditory-visual processing, children with AS D performed in the clinically impaired range, while children with ADHD performed within normal limits. This latter discrepancy is statistically significant wh ether or not FSIQ was used as a covariate (F (1,24) = 4.978, p = .036). ConnersÂ’ Parent Rating Scale Multiple ANCOVAs on the six CPRS scales (Cognitive Problems/Inattention, Hyperactivity, Perfectionism, Social Pr oblems, DSM-IV: Inattentive, DSM-IV: Hyperactive) indicate that children with AS D were rated as having significantly higher scale elevations (indicative of higher probl em levels) on the Perfectionism scale (F (1,24) = 7.252, p = .013) and Social Problems scale (F (1,24) = 5.943, p = .023), while children with ADHD were rated as ha ving significantly higher scal e elevations on the Cognitive Problems/Inattention scale (F (1,24) = 10.645, p = .003) and the DSM-IV: Inattentive scale (F (1,24) = 8.507, p = .008). Qualitatively (using recommended clinical cut-off values), children with ASD were noted to ha ve been rated within the clinical range only on the Social Problems scale, while children w ith ADHD were rated in the clinical range on the Cognitive Problems/Inattention scale, the Hyperactivity scale, the DSM-IV: Inattentive scale, and the DSM -IV: Hyperactive scale. Tabl e 3 presents the group means for the CPRS scales.

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19Table 3: Means (and Standard Deviati ons) on the ConnersÂ’ Parent Rating Scale CPRS Scale ASD ADHD p -value Effect ( N = 10) ( N = 16) Size Cognitive Problems/Inattention 57.80 69.69 0.003 1.538 (6.71) (8.75) Hyperactivity 61.90 68.19 0.512 0.511 (12.36) (13.06) Perfectionism 63.00 50.19 0.013 1.311 (9.52) (10.54) Social Problems 75.80 60.88 0.023 1.086 (12.75) (15.16) DSM-IV: Inattentive 59.60 69.94 0.008 1.180 (7.73) (9.86) DSM-IV: Hyperactive 61.60 69.06 0.295 0.627 (11.80) (12.72)

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20 Follow-up Analyses: Comparison of ASD to the ADHD Subtypes To examine whether the present findings were in part due to the heterogeneity of the ADHD group in terms of ADHD subtypes, we conducted follow-up analyses and divided the ADHD group into its two pr imary subtypes: ADHD-I and ADHD-C. Analyses were conducted using the same proce dures as described earlier. Table 4 shows the means (and standard deviations) for each group. Of note, the ASD group consists of the same children as previously describe d and the ADHD group has been divided into diagnostic subtypes, but again is comprised of the same children as detailed above.

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21Table 4: Group Means and Standard Devia tions for Age and IQ: ASD vs. ADHD subtypes ASD ( N = 10) ADHD-I ( N = 8) ADHD-C ( N = 8) p -value Chronological Age (CA) 8.70 (3.56) 9.20 (2.61) 12.04(3.21) 0.123 Full Scale IQ (FSIQ) 110.40 (13.79) 94.75 (12.45) 93.00 (14.05) 0.025 Performance IQ (PIQ) 116.20 (19.58) 96.88 (14.00) 94.63(9.46) 0.025 Verbal IQ (VIQ) 105.56 (16.11) 93.63 (12.66) 93.00 (16.71) 0.181

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22 Results of follow-up analyses using multiple ANCOVAs indicate an overall group difference on the divided atte ntion task that requires si multaneous auditory-visual processing (F (2,22) = 3.737, p = .041). Post-hoc analyses reveal that the ASD group performs significantly poorer than and in the clinically impaired range when specifically compared to the ADHD-I group, who performs w ithin normal clinical limits on this task of divided attention. An overall group diffe rence is also found on the domain of attentional control (F (2,23) = 7.152, p = .004). Bonferroni post-hoc tests demonstrate that the ASD group can be differentiated from the ADHD-C group on this attentional component, with the ASD group performing si gnificantly better and in the unimpaired range. Table 5 depicts the means (and standard deviations ) of group comparisons across attentional domains.

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23Table 5: Means (and Standard Deviations) on Attention Measures: ASD vs. ADHD subtypes Attentional Domain ASD ADHD -I ADHD-C ANOVA post-hoc ( N = 10) ( n = 8) ( n = 8) p-value comparisons Sustained Attention TEA-Ch composite score 8.72 8.13 5.88 0.146 -----------(2.62) (2.57) (3.40) CPT-II overall index score 5.26a 6.43 10.76 0.471 -----------(8.45) (10.72) (9.20) Selective Attention TEA-Ch composite score 8.70 8.50 9.06 0.901 -----------(3.14) (1.60) (2.31) Attentional Control TEA-Ch composite score 8.95 6.88 4.06 0.004 (ASD>ADHD-C) (2.87) (2.40) (2.54) Divided Attention TEA-Ch auditory-auditory subtest 7.70 8.25 6.13 0.605 ------------(3.80) (4.46) (3.91) TEA-Ch auditory-visual subtest 6.44a 9.13 6.75 0.041 (ASD
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24 Analyses reveal group differences on parent ratings of behavior on the Perfectionism scale (F (2,23) = 7.255, p = .004), the Cognitive Problems/Inattention scale (F (2,23) = 5.349, p = .013), the Hyperactivity scale(F (2,23) = 7.718, p = .003), and on the DSM-IV: Inattentive scale (F (2,23) = 5.041, p = .016) and DSM-IV: Hype ractive-Impulsive scale (F (2,23) = 4.016, p = .033). Specifically the ASD group can be differentiated from the ADHD-I group on the Perfectionism scale, with ASD rated as displaying significantly more problem behaviors, as well as on th e Cognitive Problems/Inattention and DSM-IV: Inattentive scale with the ADHD-I group rated significantly higher. Additionally, the ASD group can be discriminated fr om the ADHD-C group on the Cognitive Problems/Inattention scale, the Hyperactiv ity scale and the DSM-IV: Inattentive and Hyperactive-Impulsive scales. Table 6 presen ts the means (and standard deviations) of the parent behavior rating s for the three groups.

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25Table 6: Group Differences on Parent Ratings of Behavior: Means (and Standard Deviations)1 CPRS Scale ASD ADHD-I ADHD-C ANOVA Post-hoc ( N = 10) ( N = 8) ( N = 8) p-value Comparisons Cognitive Problems/Inattention 57.80 68.50 70.88 0.005 ASDADHD-I (9.52) (6.78) (10.87) Social Problems 75.80 57.75 64.00 0.041 ASD>ADHD-I (12.75) (17.00) (13.45) DSM-IV: Inattentive 59.60 67.38 72.50 0.020 ASD
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26 CHAPTER 4 DISCUSSION The primary goals of the current study were to characterize the profile of attentional performance in children with ASD and to i nvestigate if this childhood neurodevelopmental disorder could be different iated from ADHD in terms of attentional strengths and weaknesses or by parent ratings of behavior. The secondary aim was to examine the ASD group in comparison to the ADHD subtypes. The results suggest that th e hypothesized attentional pr ofile for these clinical populations may be more variable than anticipated. In line with the predictions, both the ADHD group and the ASD group exhibited atten tional deficits on the neuropsychological measure and on parent ratings of behavior. Although the strengths and weaknesses of the ADHD group followed apriori hypotheses, the pa ttern of attentional performance for the ASD group did not. Qualitative examina tion of the ASD group profile revealed performance within normal limits across all three attentional domains (including the CPT) and one of the two divided attention tasks. More specifi cally, although the ASD group could be discriminated from the ADHD group, the domains of attention that fostered this differentiation we re in opposition to mu ch of the literature, as well as to qualitative behavioral observat ions. Further, the study reve aled that the ASD group could be distinguished from the ADHD group at subtype level. Sustained Attention It was hypothesized that the domain of su stained attention would be a critical component of attention in distinguishing AS D from ADHD. This prediction was based

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27 on prior studies, as well as the core dia gnostic and behavioral features of ASD and ADHD. It is generally accepted that chil dren with ADHD have difficultly maintaining their attention, particularly on a relatively non-engaging task (Barkley, Grodzinsky, & DuPaul, 1992), while children with ASD are obs erved to concentrate or partake in a singular, repetitive activity for an extended period of time (Lopez, Lincoln, Ozonoff, & Lai, 2005; Pascualvaca, Fantie, Papageorgiou, & Mirskey, 1998). This discrepancy is reflected clinically within our sample, with the ADHD group performing in the impaired range and the ASD group performing within normal limits. This difference however, is not statistically significant. Sample characteristics, testing structure, and limited power may help explain our failure to detect a significant group diffe rence. Typically, an ADHD group would be expected to have poorer performance on tasks of sustained attention than was seen within our sample (Seidel & Joshko, 1990). The perf ormance of the ADHD group in the current study suggests that these children may repr esent the milder end of the disorderÂ’s spectrum. This is supported qualitativel y, as many of the children with ADHD participated in this study to determine the necessity of continuing psychostimulant medication. Additionally, our abili ty to detect a significant gr oup difference may be partly attributable to the testing environment. Although children with ASD are by definition apt to display repetitive, stereotyped behaviors, which supports the anticipated above average performance, they tend to do so only when enga ged in a task of thei r choice. In fact, when instructed to focus on a non-desired activity, children with ASD often require

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28 constant rewards (Luiselli & Hurleyy, 2005), which were not provided during the course of testing. This may account for their low average performance. Finally, the relatively small sample size of the current study may have impacted our ability to detect statistica lly significant group differences. This is supported by the medium effect size ( d = 0.576), which suggests that a la rger sample may demonstrate a significant group difference on sustained atte ntion as measured by the TEA-Ch. Selective Attention As noted in the introduction, little re search has been conducted regarding the selective attention abilities in ASD. Although selective atten tion has been more extensively studied in ADHD, limitations in study designs have led to conflicting conclusions. Results of the current pilot study indicate that both groups perform in the average range for this domain of attention. This finding is consistent with apriori hypotheses and adds to ASD literatu re with respect to the selective attenti on skills of this population. Additionally, this finding may help reconcile disparities found in ADHD literature. Attentional Control In contrast to our hypothesis, there wa s a significant group difference found in the domain of attentional control, with child ren with ASD performing significantly better than children with ADHD. Perhaps even more surprising is that children with ASD performed in the average range on this dom ain. In order to determine if the limited power of our sample caused this result we calcula ted the effect size. The large effect size ( d = 1.282) that resulted suggests that our findings are caused by a true group difference and not limited power.

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29 One possible explanation for the differen ce between our hypothesis and our finding is the complexity of this cognitive domain. Thus far in the current study we have been discussing attentional control as a component of the broade r construct of attention. However, in the past, the term attention control has been used interchangeably with a number of other terms such as attentional shift and attentional flexibility. Some might argue that these labels fall under the purview of executive function. In fact, executive function has gained much attention in the past five to ten years with a number of researchers attempting to describe the comp lex components of this construct. The question remains however, as to whether ex ecutive function and attentional control are part of the broad factor of attention or whether executive function is a stand-alone construct. These unresolved issues of te rminology and construct classification pose a significant challenge to making accurate hypotheses drawn from the ASD and ADHD literature. While resolving these issues is well beyond the scope of the current study, examination of prior studies of executive functioning may provide some guidance for future directions. In general, research has shown that children with ASD and children with ADHD are impaired on tasks of executive function (H eaton et al, 2001; Pa scualvaca et al., 1998; Goldstein, Johnson, & Minshew, 2001; Tsuchiya, Oki, Yahr a, & Fujieda, 2004). More recently studies have begun to take the multidimensional nature of executive function into account and thus have designed protoc ols to measure specifi c components of this construct. This is an important framewor k, as studies suggest that executive function deficits seen in children with developmenta l disorders vary according to the specific

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30 components that comprise the broader constr uct of executive function (Geurts et al., 2004). In fact, it is suggested that children with ASD can be differentiated from children with ADHD based on their prof ile of executive function, wi th the ASD group performing well on tasks of inhibition and poorly on tasks of set-shifting. Conve rsely, children with ADHD are reported to display poor perfor mance on tasks of inhibition and intact performance on set-shifting tasks (Goldberg et al., 2005). Despite the expected utility in differentiating ASD and ADHD based on executiv e function profiles, studies have failed to consistently replicate these anticipated disp arate patterns of perfor mance (Geurts et al., 2004). One way to conceptualize the attentional co ntrol subtests of th e TEA-Ch is as tasks that combine the executive function compone nts of inhibition and set-shifting. Although this limits our ability to draw definitive c onclusions regarding the specific components of executive function that differ between ASD a nd ADHD, the results of the current study indicate that on tasks of attentional contro l children with ASD perform within normal limits. This suggests that ch ildren with ASD do not have a generalized impairment in set-shifting when this skill is used in co njunction with other cognitive skills such as inhibition. This notion may find further support in treat ment studies noting th e effectiveness of behavioral training programs for childre n with ASD (Luiselli & Hurley, 2005). Behavioral training is based on the use of explicit instructions that when followed correctly, result in rewards. Instructions du ring behavioral traini ng often subtly utilize the concepts of inhibition and set-shifting. In fact, the instructions for the two TEA-Ch

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31 attentional control subtests follow this imp licit structure as tasks are presented with detailed instructions and explain the necessary shifts in focus. Thus, when conceptualized within this framework, it is not surprising that the current ASD study group performed well on this factor of attention. Divided Attention Results of the current study demonstrated th at children with ASD and children with ADHD have difficulty on tasks requiring divi ded attention, with bot h groups performing in the mildly impaired to low average range. Consistent with previous research, children with ASD displayed impaired performance on th e divided attention task that utilized two sensory modalities (auditory and visual) (B elmonte & Yurgelun-Todd, 2003). In fact, children with ASD were found to perform si gnificantly poorer than children with ADHD on this task, with no group difference found on the auditory-auditory task. The effect size ( d = .475) for between group differences on the auditory-visual divided attention task confirms that these findings are most likely the result of valid gr oup differences and are not attributable to the effects of small sample size. The deficit displayed by the ASD group for th e task that required the simultaneous processing of multi-modal sensory information (auditory-visual) is indicative of this populationÂ’s general sensory inte gration problems (Schaaf & Miller, 2005). Impairments in sensory integration affect the ability of children with ASD to interpret environmental information, in turn, influencing their ability to appropriately respond to the stimuli they encounter. In fact, some believe this to be the primary cause of the stereotypic behaviors displayed by this population (Schaaf & Miller, 2005).

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32 Parent Ratings of Behavior Children with ASD are often thought to have attentional deficits that have some overlap with impairments seen in ADHD. Since the goal of the current study was to characterize the pattern and extent of be haviors in a “pure” ASD population we also wanted to examine parent ratings of behavior. Furthermore, given that clinicians often use parent report measures of behavior to determine diagnoses and the presence of comorbidities it was critical to include such a measure in the current study. The behavioral similarities often observed in children with ASD and children with ADHD were reflected in the current study, as th e ASD and ADHD groups we re rated similarly on the scales of the CPRS m easuring hyperactivity. Overt, disruptive behavior, such as hyperactivity, is often the most pressing concer n for parents, teachers and clinicians as it often causes problems and disruptions in the classroom and with other children. Other, more internally-driven behaviors such as in attention, social proble ms and perfectionism are often ignored by adults because the diffi culties caused by these behaviors primarily affect the individual (Abikoff et al., 2002). In the current pilot study, children with AS D were rated significantly different from children with ADHD on scales of the CPRS measuring inattention, social problems and perfectionism. The ASD group was rated as having elevated social problems and perfectionist behavior when compared to th e ADHD group. In contrast, children with ADHD were rated as displaying significantly mo re inattentive behavi ors. These findings highlight the importance of evaluating a range of behaviors beyond those that are overtly disruptive (i.e., hyperactivity) when attempting to distinguish behavioral profiles of children with ADHD from those with ASD. While children with ADHD and ASD may appear similar in terms of magnitude of disr uptive behaviors such as hyperactivity, the

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33 current study results indicate that they can be differentiated on ra tings of inattentive behaviors, perfectionism and social problems. This result is expected due to the different diagnostic features of ASD and ADHD. However, the si milar level of hyperactivity noted by the parents of the ASD and ADHD groups explains the similar observable behavior often commented on with respect to these developmental disorders. Follow-up Analyses: ASD compared to ADHD Subtypes Although it is generally accepted that the ADHD subtypes differ in their behavioral presentation of hype ractivity, it is le ss clear if the ADHD subtypes differ in their respective attent ional profiles. Nonetheless we wondered if our findings were influenced by the heterogeneity of our ADHD sample. In particular, we wanted to confirm that our “pure” ASD group could be discriminated from each of the ADHD subtypes. Therefore, we divided the ADHD group into it s two primary subtypes, ADHDI and ADHD-C. Results of the follow-up an alyses provide more detailed information about the group characteristics driving the differences found in attentiona l control and divided attention. More specifically, it app ears that the difference in the domain of attentional control was between ASD and AD HD-C and the difference in the multi-modal divided attention was between ASD and ADHD -I. This finding would provide useful information for clinicians who were examini ng the performance prof ile of a child with known ASD, but an unclear ADHD subtype comorbidity. Limitations and Strengths of Current Study The implications of our findings are temp ered by the limitations of the current study. Due to the nature of a pilot study our sample size, and therefore power, was relatively small. This limited our ability to apply Bonferroni corrections to control for error rates. Additionally, participants in both groups displayed higher levels of

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34 functioning than what is expected based on the general population of children diagnosed with ASD or ADHD. This restricts our ability to generalize our results to children with ASD and ADHD who display greater cogniti ve and behavioral impairments. Furthermore, information regarding socioec onomic status of the participants was not collected for this pilot study. It is possible that the groups c ould differ in this respect, or that the groups are not representative of the spectrum of socioeconomic status seen in the general population. As such, it would be important to include this data in any future studies. In contrast, there are a number of unique strengths to the current study. To the best of the investigatorsÂ’ knowledge there are no other studies that have examined the multidimensional nature of attention in children with ASD using a series of tasks within a single study design. Utilizing ta sks within a single test batt ery has the added benefit of comparable normative data and testing st ructure, which facilitates performance comparisons across attentional domains. Furt hermore, although the relationship between ASD and ADHD has been studied (e.g. with regard to executive function and shared symptomatology), few researcher s have concentrated specifically on the attentional profiles of these populations. Th e results of the current study suggest that it may be difficult to differentiate ch ildren with ASD from children with ADHD on the basis of broadly defined attentional sk ills and behaviors. This finding highlights the need to utilize multidimensional assessments when making determinations about the presence of comorbid ADHD in children with ASD. Future Directions Using a multidimensional model of attention and parent ratings of behavior, the current pilot study successfully describes the expected attentional profile for ASD, as

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35 well as illustrates how the pattern of ASD attentional performance differs from that seen in ADHD. This is an important first step in providing clinicians with information to aid in the determination of comorbid ADHD in ASD populations. The current study also highlights some of the challenges, particularly in light of DSM-IV criteria, for receiving a diagnosis of both ASD and ADHD. The next step for this area of rese arch is to confirm our findings in a larger sample that represen ts the broader severity spectrum of ASD and ADHD. If replication were successful, the s ubsequent step would be to include children with comorbid ASD and ADHD (whether o fficially diagnosed or implied due to treatment with psychostimulants) to examin e whether the profile of this third group would be unique or represent a combination of the profiles of the primary diagnostic groups. Given the challenges to making a comorbid diagnosis of this ty pe, it is likely that group criteria would also need to incor porate information regarding pharmacological treatment or other indirect m easures of comorbidity. It is hypothesized that the resulting profile would be a composite of the pattern of attentional performance seen in the two “pure” groups of the current study. In other words, the comorbid group would display the ASD deficits plus the addi tional ADHD deficits. However, it is also possible that the comorbid group could display a third, unique profile.

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36 LIST OF REFERENCES Abikoff, H.B., Jensen, P.S., Arnold, L.E., Ho za, B., Hechtman, L., Pollack, S., Martin, D., Alvir, J., March, J.S., Hinshaw, S., Vitiello, B., Newcorn, J., Greiner, A., Cantwell, D.P., Conner, C.K., Elliot, G ., Greenhill, L.L., Kraemer, H., Pelham, W.E., Severe, J.B., Swanson, J.M., Wells, K., & Wigal, T. (2002). Observed classroom behavior of children with ADHD: Relationshi p to gender and comobidity-1-attention deficit hyperactivity disorder. Journal of Abnormal Child Psychology, 30, 349-359. Althaus, M., Van Roon, A.M., Mulder, L.J.M., Mulder, G., Aamoudse, C.C., & Minderaa, R.B. (2004). Autonomic re sponse patterns observed during the performance of an attention-demanding task in two groups of children with autistictype difficulties in social adjustment. Psychophysiology, 41, 893-911. American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author. Barkley, R.A., Grodzinsky, G., & DuPaul, G.J. (1992). Frontal lobe functions in attention deficit disorder with and without hyperac tivity: A review and research report. Journal of Abnormal Child Psychology, 20, 163-188. Belmonte, M.K., & Yurgelun-Todd, D.A. (2003). Functional anatomy of impaired selective attention and compensa tory processing in autism. Cognitive Brain Research, 17, 651-664. Burak, J.A. (1994). Selective attention defic its in persons with autism: Preliminary evidence of an inefficient attentional lens. Journal of Abnormal Psychology, 103, 535-543. Casey, B.J., Gordon, C.T., Mannhein, G.B ., & Rumsey, J.M. (1993). Dysfunctional attention in autistic savants. Journal of Clinical Expe rimental Neuropsychology, 15, 933-946. Conners, C.K. (1990). ConnersÂ’ Teacher and Parent Rating Scales. Toronto: MultiHealth Systems. Conners, C.K. (1995). ConnersÂ’ Continuous Performance Test. Toronto: Multi-Health Systems. Conners, C.K. (1997). ConnersÂ’ Parent Rati ng Scale-Revised (L). Toronto: Multi-Health Sytems.

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37 Cooley, E.L., & Morris, R.D. (1990). Attent ion in Children: A neuropsychologically based model for assessment. Developmental Neuropsychology, 6 , 239-274. Courchesne, E., Townsend, J., Akshoomoff , N.A., Saitoh, O., Yeung-Courchesne, R., Lincoln, A.J., James, E.H., Haas, R. H., Schreibman, L., & Lau, L. (1994). Impairment in shifting attention in autistic and cerebellar patients. Behavioral Neuroscience, 108, 848-865. Fayed, N., & Modrego, P.J. (2005). Compar ative study of cerebral white matter in Autism and Attention-deficit/Hyperactivity Disorder by means of magnetic resonance spectroscopy. Academy of Radiology, 12, 566-568. Fein, D., Dixon, P., Paul, J., & Levin, H. ( 2005). Brief report: Pervasive developmental disorder can evolve into ADHD: Case illustrations. Journal of Autism and Developmental Disorders, 35, 525-534. Geurts, H.M., Verte, S., Oosterlaan, J., Ro eyers, H., & Sergeant, J.A. (2004). How specific are executive function deficits in attention deficit hyp eractivity disorder and autism? Journal of Child Psychology and Psychiatry, 45, 836-863. Gioia, G.A., Isquith, P.K., Guy, S.C., & Kenworthy, L. (2000). Behavior Rating Inventory of Executive Function. Odessa: Psychologica l Assessment Resources. Goldberg, M.C., Mostofsky, S.H., Cutting, L. E., Mahone, E.M., Astor, B.C., Denckla, M.B., & Landa, R.J. (2005). Subtle executiv e impairment in children with autism and children with ADHD. Journal of Autism and Developmental Disorders, 35, 279-293. Goldstein, G., Johnson, C.R., & Minshew, N.J. (2001). Attentional processes in Autism. Journal of Autism and Developmental Disorders, 31, 433-440. Goldstein, S., & Schwebach, A.J. (2004). Th e comorbidity of pervasive developmental disorder and attention deficit hyperactivity disorder: Results of a retrospective chart review. Journal of Autism and Developmental Disorders, 34, 329-339. Grady, D.L., Harxhi, A., Smith, M., Flodma n, P., Spence, M.A., Swanson, J.M., & Moyzis, R.K. (2005). Sequence variants of the DRD4 gene in autism: Further evidence that rare DRD4 7R Haplotypes are ADHD specific. American Journal of Medical Genetics Part B (Neu ropsychiatric Genetics), 136B, 33-35. Handen, B.L., McAuliffe, S., Janosky, J ., Feldman, H., & Breaux, A.M. (1994). Classroom behavior and children with ment al retardation: Co mparison of children with and without ADHD. Journal of Abnormal Child Psychology, 22, 267-280. Handen, B.L., Johnson, C.R., & Lubetsky. (200 0). Efficacy of methylphenidate among children with autism and symptoms of a ttention-deficit hyperactivity disorder. Journal of Autism and Developmental Disorders, 30, 245-255.

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39 Nicolson, R., & Castellanos, F.X. (2000). Commentary: Considerations on the pharmacotherapy of attention deficits and hyperactivity in children with autism and other pervasive developmental disorders. Journal of Autism and Developmental Disorders, 30, 461-462. Noterdaeme, M., Amorosa, H., Mildenberg er, K., Sitter, S., & Minow, F. (2001). Evaluation of attention problems in ch ildren with autism and children with a specific language disorder. European Child & Adolescent Psychiatry, 10, 58-66. Pascualvaca, D.M., Fantie, B.D., Papageorgi ous, M., & Mirsky, A.F. (1998). Attentional capacities in children with autism: Is ther e a general deficit in shifting focus? Journal of Autism and Developmental Disorders, 28, 467-478. Schaaf, R.C., & Miller, L.J. (2005). Occupational therapy using a sensory integrative approach for children with developmental disabilities. Mental Retardation and Developmental Disabilities Research Reviews, 11, 143-148. Schopler, E., Reichler, R.J., & Renner, B.R. (1988). The Childhood Autism Rating Scale. Los Angeles: Western Psychological Services. Seidel, W., & Joshko, M. (1990). Evidence of difficulties in sustained attention in children with ADHD. Journal of Abnormal Child Psychiatry, 18, 217-229. Sergeant, J.A., & Van der Meere, J.J. (1990) . Convergence of appro aches in localizing the hyperactivity deficit. In Lahe y, B.B., & Kazdin, A.E. (Eds). Advancements in clinical child psychology, 13. New York: Plenum Press, 1990. p. 207-245. Siegel, B.V., Nuechterlein, K.H., Abel, L ., Wu, J.C., & Buchsbaum, M.S. (1995). Glucose metabolic correlates of continuous performance test performance in adults with a history of infantile auti sm, schizophrenics, and controls. Schizophrenia Research, 17, 85-94. Smalley, S.L., Kustanovich, V., Minassian, S.L., Stone, J.L., Ogdie, M.N., McGough, J.J., McCracken, J.T., MacPhie, I.L., Fr ancks, C., Fisher, S.E., Cantor, R.M., Monaco, A.P., & Nelson, S.F. (2002). Genetic linkage of attentiondeficity/hyperactivity diso rder on chromosome 16p13, in region implicated in autism. American Journal of Human Genetics, 71, 959-963. Tsuchiya, E., Oki, J., Yahara, N., & Fujieda , K. (2004). Computerized version of the Wisconsin card sorting test in children w ith high-functioning au tistic disorder or attention-deficit/hyperactivity disorder. Brain & Development, 27, 233-236. Weller, E.B., Fristad, M.A., Roone y, M.T., & Weller, R.A. (1999). ChildrenÂ’s Interview for Psychiatric Syndromes Parent Version. Philadelphia: American Psychiatric Publishing Inc.

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40 Whalen, C., & Schreibman, L. (2003). Joint at tention training for children with autism using behavior modification procedures. Journal of Child Psychology and Psychiatry, 44 , 456-468.

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41 BIOGRAPHICAL SKETCH Cara Kimberg was born and raised in Hartsd ale, NY, the eldest of two children of Judi and Bernie Kimberg. She earned a bachelorÂ’s degree in psychology with a concentration in neuroscience at Duke Universi ty. Cara entered the clinical and health Psychology program at the University of Fl orida in 2004. During her study at UF, she has worked as a research assistant in a pedi atric neuropsychology lab. CaraÂ’s mentor is Shelley C. Heaton, Ph.D., and her intere sts include childhood neurodevelopmental disorders such as Autism Spectrum Disorders and Attention Deficit Hyperactivity Disorder. She plans to work in a clinical research setting af ter earning her doctoral degree in clinical psychology.