Response inhibition in adults with autism spectrum disorder compared to attention deficit/hyperactivity disorder

Characterizing Inhibitory Control Challenges Among Autistic Adults: An Examination of Demographic and Psychiatric Moderators and Associations with Anxiety Symptomatology

Autism spectrum disorder is associated with elevated rates of mental health difficulties and executive function challenges. Emerging evidence links executive function to mental health in autistic individuals. However, less is known about (a) everyday inhibitory control difficulties among autistic adults; (b) the influence of sex assigned at birth and co-occurring attention deficit/hyperactivity disorder (ADHD) features on inhibition challenges; and (c) relations between inhibition challenges and anxiety symptoms. Drawing upon data from 732 autistic adults aged 18-83, this online study examined self-reported inhibitory control in autistic adults and the influence of assigned sex and ADHD screening status (based on a positive screening score on a self-report tool) on the degree of inhibitory control challenges experienced. In addition, this research examined relations between inhibitory control challenges and anxiety symptoms, and the moderating role of assigned sex and ADHD screening status in this relationship. Autistic adults endorsed significantly more inhibitory control challenges relative to published norms. Participants assigned female reported more difficulties in inhibitory control relative to sex-adjusted normative expectations than participants assigned male. Participants who screened positive for ADHD reported more inhibitory control challenges than those who screened negative. Greater endorsement of inhibitory control challenges was associated with greater anxiety symptomatology; this relationship was moderated by ADHD screening status, but not by assigned sex. Inhibitory control is an area of difficulty in autistic adults and is associated with anxiety symptomatology, suggesting that inhibitory control may be a valuable intervention target to improve emotional well-being in autistic adults.

Executive function among adults with autism spectrum disorder: An eye-tracking study

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by social communication deficits and repetitive behaviors. Eye movement abnormalities are common in ASD, suggesting underlying cognitive impairments such as working memory and response inhibition. However, several investigations suggest deficits in inhibitory control and working memory among individuals with ASD, whereas others indicate performance levels similar to typically developing individuals. The variability observed in executive function (EF) profiles across various tasks and age cohorts underscores the intricate interplay between ASD and cognitive functioning. Therefore, to bridge these gaps and gain a comprehensive understanding of the specific components of EF affected by ASD, this study used eye-tracking technology to analyze cognitive processing. In the working memory task, the clinical group comprised adults with ASD (N = 52), aged between 25 and 47 years (M = 31.65 years, SD = 6.05), while the control group (non-ASD) included individuals (N = 53), aged between 25 and 55 years (M = 33.15 years, SD = 5.92). For the response inhibition task, the clinical group consisted of adults with ASD (N = 50), aged between 25 and 47 years (M = 31.66 years, SD = 6.153), and the control group comprising individuals (N = 56), aged between 25 and 55 years (M = 33.03 years, SD = 5.80). The study revealed that individuals with ASD demonstrate notable impairments and increased errors in EF, encompassing inhibitory control and working memory when compared to non-ASD individuals. Additionally, individuals with ASD exhibited differences in fixation duration, saccade count, and fixation count compared to their non-ASD counterparts, further highlighting the distinct cognitive profile associated with ASD. Analyzing EF in adults with ASD through eye movement patterns provides valuable insights into the underlying cognitive processes and attentional mechanisms at play.

Modality-specific associations between sensory differences and autistic traits

LAY ABSTRACT

Sensory symptoms are a major source of distress for many autistic people, causing anxiety, stress, and avoidance. Sensory problems are thought to be passed on genetically together with other autistic characteristics, such as social preferences. This means that people who report cognitive rigidity and autistic-like social function are more likely to suffer from sensory issues. We do not know what role the individual senses, such as vision, hearing, smell, or touch, play in this relationship, because sensory processing is generally measured with questionnaires that target general, multisensory issues. This study aimed to investigate the individual importance of the different senses (vision, hearing, touch, smell, taste, balance, and proprioception) in the correlation with autistic traits. To ensure the results were replicable, we repeated the experiment in two large groups of adults. The first group contained 40% autistic participants, whereas the second group resembled the general population. We found that problems with auditory processing were more strongly predictive of general autistic characteristics than were problems with the other senses. Problems with touch were specifically related to differences in social interaction, such as avoiding social settings. We also found a specific relationship between proprioceptive differences and autistic-like communication preferences. The sensory questionnaire had limited reliability, so our results may underestimate the contribution of some senses. With that reservation in mind, we conclude that auditory differences are dominant over other modalities in predicting genetically based autistic traits and may therefore be of special interest for further genetic and neurobiological studies.

Disentangling response initiation difficulties from response inhibition in autism spectrum disorder: A sentence-completion task

It has been proposed that individuals with autism spectrum disorder (ASD) struggle both with response initiation and with response inhibition, both of which are functions of the executive system. Experimental tasks are unlikely pure measures of a single cognitive domain, and in this study we aim at understanding the contributions of response initiation difficulties to possible deficits in inhibitory control in autism. A sample of adults diagnosed with ASD and a control sample participated in this study. To participants it was asked to perform a sentence-completion task with two different condition: Part A—targeting response initiation and Part B—engaging inhibitory processes. Importantly, we have analyzed the B-A latencies that have been proposed for the removal of the response initiation confound effect. Results show that no differences between the groups were found in accuracy measures, either in Part A (ASD: M = 0.78; Controls: M = 0.90) nor Part B (ASD: M = 0.03; Controls: M = 0.02). However, in both conditions autistic participants were significantly slower to respond than the group of participants with typical development (Part A—ASD: M = 2432.5 ms; Controls M = 1078.5 ms; Part B—ASD M = 6758.3 ms; Controls M = 3283.9 ms). Critically, we show that when subtracting the response times of Part A from Part B (B-A latencies) no group differences attributable to inhibitory processes remained (ASD: M = 4325.76; Controls: M = 2205.46). With this study we corroborate the existence of difficulties with response initiation in autism and we question the existence of troubles in inhibition per se.

Computer-Based Assessment and Self-Report Measures of Executive Functions in High-Functioning Adults with Autism

This study analyzes the profile of executive functions (EF) in high-functioning adults with autism (HFA), both in terms of performance on four computer-based tasks, as well as how these functions are perceived by the individuals through self-reporting measures. The study included 64 participants: 32 individuals with HFA, and 32 typically developing controls. Four CANTAB tasks were used (assessing spatial working memory, planning, visual memory, and inhibition), as well as a self-reported measure of executive functions (BDEFS) and a scale for the severity of autism symptoms (RAADS-R). The participants in the ASD group performed significantly lower than the control group on all four computer-based tasks, as measured by the total number of errors made (for the spatial working memory, visual memory, and inhibition tasks) and the number of problems solved at the first choice (for the planning task). No correlation was found in the ASD group between the severity of autism symptoms and the computer-based measures. These findings provide evidence that HFA adults may have various executive functioning impairments, and subsequent daily life problems, but these deficits do not necessarily correlate with the severity of core ASD symptoms.

A review of executive functioning challenges and strengths in autistic adults

Objective: There has been a steady rise in research characterizing executive functioning (EF) impairments in autistic individuals but limited research investigating EF strengths. This review provides a summary of current EF research in autistic adults with a focus on EF challenges and strengths and potential sources of heterogeneity in research findings. New avenues for addressing gaps in our understanding of EF strengths are proposed.Method: A review of the EF literature was conducted. One hundred twenty-four studies of inhibition, working memory, cognitive flexibility, fluency, planning, decision-making, and subjective measures of EF in autistic adults were included.Results: Autistic adults with average intellectual functioning demonstrate difficulties with cognitive flexibility, phonemic fluency, and working memory. Strengths in planning, decision-making, and semantic verbal fluency were evident in some but not all studies. Findings regarding inhibition are inconclusive. Key findings across each EF domain are discussed and sources of potential heterogeneity across studies were evaluated. The type of measure used appears to contribute to heterogeneous findings. Subjective EF measures revealed more consistent findings of deficits in autistic adults than objective EF measures.Conclusions: Research reveals areas of EF weaknesses as well as strengths in autistic adults. Unlike EF challenges, EF strengths are not well understood. Future research identifying EF strengths is needed to improve services and supports for autistic adults. Further investigation of potential factors that interact with or constrain EF such as comorbid disorders, verbal ability, sensory processing, and other factors specific to autism will be critical to move the field forward and increase understanding of how EF is related to everyday functioning in autistic adults.

The Monash Autism-ADHD genetics and neurodevelopment (MAGNET) project design and methodologies: a dimensional approach to understanding neurobiological and genetic aetiology

Background

ASD and ADHD are prevalent neurodevelopmental disorders that frequently co-occur and have strong evidence for a degree of shared genetic aetiology. Behavioural and neurocognitive heterogeneity in ASD and ADHD has hampered attempts to map the underlying genetics and neurobiology, predict intervention response, and improve diagnostic accuracy. Moving away from categorical conceptualisations of psychopathology to a dimensional approach is anticipated to facilitate discovery of data-driven clusters and enhance our understanding of the neurobiological and genetic aetiology of these conditions. The Monash Autism-ADHD genetics and neurodevelopment (MAGNET) project is one of the first large-scale, family-based studies to take a truly transdiagnostic approach to ASD and ADHD. Using a comprehensive phenotyping protocol capturing dimensional traits central to ASD and ADHD, the MAGNET project aims to identify data-driven clusters across ADHD-ASD spectra using deep phenotyping of symptoms and behaviours; investigate the degree of familiality for different dimensional ASD-ADHD phenotypes and clusters; and map the neurocognitive, brain imaging, and genetic correlates of these data-driven symptom-based clusters.

Methods

The MAGNET project will recruit 1,200 families with children who are either typically developing, or who display elevated ASD, ADHD, or ASD-ADHD traits, in addition to affected and unaffected biological siblings of probands, and parents. All children will be comprehensively phenotyped for behavioural symptoms, comorbidities, neurocognitive and neuroimaging traits and genetics.

Conclusion

The MAGNET project will be the first large-scale family study to take a transdiagnostic approach to ASD-ADHD, utilising deep phenotyping across behavioural, neurocognitive, brain imaging and genetic measures.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00457-3.

Characteristic Executive Dysfunction for High-Functioning Autism Sustained to Adulthood

The comprehensiveness and severity of executive dysfunction in high-functioning autism (HFA) spectrum disorder have not reached a unified conclusion especially in patients in adulthood. Clarifying this issue is critical for guiding clinical diagnosis and targeted intervention. The primary objective of the present meta-analysis was to study the characteristics of executive function (EF) in adults with HFA compared to typically developing (TD) adults, by taking five key components into consideration, including inhibition, working memory, flexibility, planning, and fluency. The PubMed and Embase databases were searched to identify peer-reviewed studies that compared EF in adults with and without HFA from 1980 to November 2018. Hedges' g effect sizes were computed to measure the primary outcome. Moderators like age, sex, and diagnostic tools were controlled using meta-regressions. Forty-two studies satisfying the selection criteria were included, which resulted in a large sample size of 2419 participants. A moderate overall effect size for reduced EF across domains was found in adults with HFA, compared with TD (g = 0.57, 95% confidence interval 0.47-0.66). Subsequently, a broad executive dysfunction was found in adults with HFA in this study (flexibility [g = 0.69], planning [g = 0.64], inhibition [g = 0.61], working memory [g = 0.48], fluency [g = 0.42]), with the predominated impairment on flexibility and planning. Taken together, these results provide evidence for the executive dysfunction hypothesis and may assist in the clinical diagnosis and targeted intervention, suggesting the necessity of sustained intervention on EF for individuals with HFA from childhood to adulthood. LAY SUMMARY: The meta-analysis explored the characteristics of EF in adults with high-functioning autism (HFA) comparing to typically developing controls. Moderate effect sizes for reduced EF across domains were found in adults with HFA, with the flexibility and planning being the most predominately impaired. A comprehensive measurement of EF in adults with HFA has important clinical implications for the diagnosis, treatment, prognosis, and a fundamental understanding for developmental trajectory of these patients.

Executive Function: Cognition and Behaviour in Adults with Autism Spectrum Disorders (ASD)

Studies of executive function (EF) in autism spectrum disorder (ASD) have reported mixed findings. Possible confounds include EF domain assessed and co-occurring neurodevelopmental diagnoses. EF task performance across multiple domains and everyday function of autistic adults (n = 110) was significantly different to age- and IQ-matched controls (n = 31). Although significantly more likely to fall into the clinically impaired range, 35.8% of the ASD group showed no impairment on EF measures. Factor analysis revealed a single unifying EF construct rather than a selective pattern of impairment. Dysexecutive behaviours were frequently reported in the ASD group, unrelated to Autism symptoms, EF task performance or co-occurring conditions. This study suggests autistic adults can experience clinically significant executive function difficulties and co-occuring dysexecutive behaviours that are disabling in everyday life.

A Review of Language, Executive Function, and Intervention in Autism Spectrum Disorder

Difficulties with both executive functions and language skills are common but variable in autism spectrum disorder (ASD). Executive functions and language skills are related to one another, such that vocabulary, syntax, and pragmatics are related to domains of working memory, shifting, and inhibition in ASD, although the directionality of these relationships remains unclear. Moreover, interventions that target pragmatic ability have been found to improve executive function skills, and conversely, executive function interventions are linked with improvements in social skills in children with ASD. We review the literature on executive functions, language skills, and their relationship in ASD; discuss factors that may be driving inconsistent findings; and explore clinical applications from the research thus far.

Adapted cognitive behavior therapy for obsessive-compulsive disorder with co-occurring autism spectrum disorder: A clinical effectiveness study

Obsessive-compulsive disorder and autism spectrum disorder commonly co-occur. Adapted cognitive behavior therapy for obsessive-compulsive disorder in adults with autism spectrum disorder has not previously been evaluated outside the United Kingdom. In this study, 19 adults with obsessive-compulsive disorder and autism spectrum disorder were treated using an adapted cognitive behavior therapy protocol that consisted of 20 sessions focused on exposure with response prevention. The primary outcome was the clinician-rated Yale-Brown Obsessive-Compulsive Scale. Participants were assessed up to 3 months after treatment. There were significant reductions on the Yale-Brown Obsessive-Compulsive Scale at post-treatment (d = 1.5), and improvements were sustained at follow-up (d = 1.2). Self-rated obsessive-compulsive disorder and depressive symptoms showed statistically significant reductions. Improvements in general functioning and quality of life were statistically non-significant. Three participants (16%) were responders at post-treatment and four (21%) were in remission from obsessive-compulsive disorder. At follow-up, three participants (16%) were responders and one (5%) was in full remission. Adapted cognitive behavior therapy for obsessive-compulsive disorder in adults with co-occurring autism spectrum disorder is associated with reductions in obsessive-compulsive symptoms and depressive symptoms. However, outcomes are modest; few patients were completely symptom free, and treatment engagement was low with few completed exposures and low adherence to homework assignments. We identify and discuss the need for further treatment refinement for this vulnerable group.

Patterns of Nonsocial and Social Cognitive Functioning in Adults With Autism Spectrum Disorder: A Systematic Review and Meta-analysis

IMPORTANCE

Many studies have investigated impairments in cognitive domains in adults with autism spectrum disorder (ASD). Yet, to date, a comprehensive overview on the patterns of cognitive functioning is lacking.

OBJECTIVE

To provide an overview of nonsocial and social cognitive functioning in various domains in adults with ASD, allowing for comparison of the severity of deficits between different domains.

DATA SOURCES

A literature search performed in an academic medical setting was conducted using PubMed, PsycINFO, Embase, and Medline databases with the combination of the following free-text and Medical Subject Headings where applicable: [cogniti* OR neurocogniti* OR neuropsycholog* OR executive function* OR IQ OR intelligence quotient OR social cognition OR emotion perception OR affect perception OR emotion recognition OR attribution OR ToM OR mentalising OR mentalizing OR prosody OR social knowledge OR mind reading OR social cue OR social judgment] AND [autis* OR ASD OR Asperger OR Asperger's OR PDD OR pervasive developmental disorder]. The search was further limited to studies published between 1980 (first inclusion of autism diagnosis in the DSM-III) and July 2018.

STUDY SELECTION

Studies included were published as a primary peer-reviewed research article in English, included individuals with ASD 16 years or older, and assessed at least 1 domain of neurocognitive functioning or social cognition using standard measures.

DATA EXTRACTION AND SYNTHESIS

Of 9892 articles identified and screened, 75 met the inclusion criteria for the systematic review and meta-analysis.

MAIN OUTCOMES AND MEASURES

Hedges g effect sizes were computed, and random-effects models were used for all analyses. Moderators of between-study variability in effect sizes were assessed using meta-regressions.

RESULTS

The systematic review and meta-analysis included 75 studies, with a combined sample of 3361 individuals with ASD (mean [SD] age, 32.0 [9.3] years; 75.9% male) and 5344 neurotypical adults (mean [SD] age, 32.3 [9.1] years; 70.1% male). Adults with ASD showed large impairments in theory of mind (g = -1.09; 95% CI, -1.25 to -0.92; number of studies = 39) and emotion perception and processing (g = -0.80; 95% CI, -1.04 to -0.55; n = 18), followed by medium impairments in processing speed (g = -0.61; 95% CI, -0.83 to -0.38; n = 21) and verbal learning and memory (g = -0.55; 95% CI, -0.86 to -0.25; n = 12). The least altered cognitive domains were attention and vigilance (g = -0.30; 95% CI, -0.81 to 0.21; n = 5) and working memory (g = -0.23; 95% CI, -0.47 to 0.01; n = 19). Meta-regressions confirmed robustness of the results.

CONCLUSIONS AND RELEVANCE

Results of this systematic review and meta-analysis suggest that adults with ASD show impairments in social cognitive domains and in specific nonsocial cognitive domains. These findings contribute to the understanding of the patterns of cognitive functioning in adults with ASD and may assist in the identification of targets for cognitive interventions.

Non-diagnostic symptoms in a mouse model of autism in relation to neuroanatomy: the BTBR strain reinvestigated

Several mouse models of autism spectrum disorder (ASD), including the BTBR T + tf/J (BTBR) inbred strain, display a diverse array of behavioral deficits with particular face validity. Here we propose that phenotyping these preclinical models of ASD should avoid excessive reliance on appearance validity of the behavioral observations. BTBR mice were examined in three non-diagnostic symptoms modalities, beside an anatomical investigation for construct validity. The BTBR strain displayed poor sensorimotor integration as reflected by shorter stride length and greater latency on the balance beam task (BBT) when compared with C57BL/6 (B6) controls. Also, locomotor indices in the open-field task (OFT) revealed that BTBR mice traveled longer distances with a remarkably faster exploration than the B6 group in favor of hyperactivity and impulsiveness. Furthermore, analysis of spatial performance including search strategies in the Morris water task (MWT) indicated spatial impairment in the BTBR strain due to failure to employ spatial strategies during navigation. Quantitative cytoarchitectonics and volumetric examinations also indicated abnormal cortical and subcortical morphology in the BTBR mice. The results are discussed in relation to the neuroanatomical correlates of motor and cognitive impairments in the BTBR strain. We conclude that non-diagnostic autistic-like symptoms in the BTBR mouse strain can be impacted by autism risk factors in a similar way than the traditional diagnostic signs.

Cognitive Processes in ADHD and Asperger's Disorder: Overlaps and Differences in PASS Profiles

OBJECTIVE

Many studies report on the usefulness of the evaluation of Executive Functions (EF) in the assessment of participants with ADHD, while others underline how deficits of EF in these participants are not consistent and that the same executive deficits are present in many other disorders, particularly in Asperger's disorder. Using the Planning Attention Simultaneous Successive (PASS) theory, the present study explores the cognitive profiles of participants with ADHD or Asperger's disorder and compares the cognitive functioning of these two diagnostic groups.

METHOD

Forty-four children, 24 with a diagnosis of ADHD and 20 with a diagnosis of Asperger's disorder, participated and their cognitive processes were evaluated with the Cognitive Assessment System.

RESULTS

Results underline specific cognitive profiles in ADHD and Asperger's disorder characterized by weaknesses in planning and attention, but with a diverse level of severity.

CONCLUSION

Implications of the different cognitive profiles of these diagnostic groups are discussed.

Priming Facial Gender and Emotional Valence: The Influence of Spatial Frequency on Face Perception in ASD

Adolescents with and without autism spectrum disorder (ASD) performed two priming experiments in which they implicitly processed a prime stimulus, containing high and/or low spatial frequency information, and then explicitly categorized a target face either as male/female (gender task) or as positive/negative (Valence task). Adolescents with ASD made more categorization errors than typically developing adolescents. They also showed an age-dependent improvement in categorization speed and had more difficulties with categorizing facial expressions than gender. However, in neither of the categorization tasks, we found group differences in the processing of coarse versus fine prime information. This contradicted our expectations, and indicated that the perceptual differences between adolescents with and without ASD critically depended on the processing time available for the primes.

The clinical utility of social information processing theory in assessing and treating offenders with autism spectrum disorder

Purpose

Social deficits are central within conceptualisations of autism spectrum disorder (ASD), and separately linked to offending behaviour. Social problem-solving interventions are often used with offenders, but little research has examined the social information processing (SIP) skills of individuals with ASD and a history of criminal offending behaviours. The paper aims to discuss this issue.

Design/methodology/approach

This conceptual paper will introduce the SIP model, review SIP research as applied to those with ASD and in forensic populations, and further consider the relevance to the assessment and treatment of offenders with ASD.

Findings

Difficulties in all areas of the SIP model are noted in ASD and research suggests these difficulties may be directly linked to behaviour.

Practical implications

It is possible that identifying SIP abilities and deficits could improve the effectiveness of rehabilitation programmes for this group.

Originality/value

This paper reviews the utility of social information models in the offending behaviour of people with ASD.

Real-World Executive Functions in Adults with Autism Spectrum Disorder: Profiles of Impairment and Associations with Adaptive Functioning and Co-morbid Anxiety and Depression

Although executive functioning (EF) difficulties are well documented among children and adolescents with autism spectrum disorder (ASD), little is known about real-world measures of EF among adults with ASD. Therefore, this study examined parent-reported real-world EF problems among 35 adults with ASD without intellectual disability and their correlations with adaptive functioning and co-morbid anxiety and depression symptomatology. A variable EF profile was found with prominent deficits occurring in flexibility and metacognition. Flexibility problems were associated with anxiety-related symptoms while metacognition difficulties were associated with depression symptoms and impaired adaptive functioning (though the metacognition-adaptive functioning relationship was moderated by ADHD symptoms). These persistent EF problems are predictors of broader functioning and therefore remain an important treatment target among adults with ASD.

Development of the Brazilian version of the Child Hayling Test

Abstract Introduction: The Hayling Test assesses the components of initiation, inhibition, cognitive flexibility and verbal speed by means of a sentence completion task. This study presents the process of developing the Brazilian version of the Child Hayling Test (CHT) and reports evidence of its content validity. Methods: 139 people took part in the study. The adaptation was performed by seven translators and 12 specialist judges. An initial sample of 92 healthy children was recruited to test a selection of sentences adapted from previous adult and pediatric versions of the instrument, and a sample of 28 healthy children was recruited for pilot testing of the final version. The instrument was developed in seven stages: 1) translation, 2) back-translation, 3) comparison of translated versions, 4) preparation of new stimuli, 5) data collection with healthy children to analyze comprehension of the stimuli and analyses by the authors against the psycholinguistic criteria adopted, 6) analyses conducted by judges who are specialists in neuropsychology or linguistics, and 7) the pilot study. Results: Twenty-four of the 72 sentences constructed were selected on the basis of 70-100% agreement between judges evaluating what they assessed and level of comprehensibility. The pilot study revealed better performance by older children, providing evidence of the instrument's sensitivity to developmental factors. Conclusions: Future studies employing this version of CHT with clinical pediatric populations who have frontal lesions and dysfunctions and in related areas are needed to test functional and differential diagnoses of preserved or impaired executive functions.

Independence of Hot and Cold Executive Function Deficits in High-Functioning Adults with Autism Spectrum Disorder

Individuals with autistic spectrum disorder (ASD) display diverse deficits in social, cognitive and behavioral functioning. To date, there has been mixed findings on the profile of executive function deficits for high-functioning adults (IQ > 70) with ASD. A conceptual distinction is commonly made between "cold" and "hot" executive functions. Cold executive functions refer to mechanistic higher-order cognitive operations (e.g., working memory), whereas hot executive functions entail cognitive abilities supported by emotional awareness and social perception (e.g., social cognition). This study aimed to determine the independence of deficits in hot and cold executive functions for high-functioning adults with ASD. Forty-two adults with ASD (64% male, aged 18-66 years) and 40 age and gender matched controls were administered The Awareness of Social Inference Test (TASIT; emotion recognition and social inference), Letter Number Sequencing (working memory) and Hayling Sentence Completion Test (response initiation and suppression). Between-group analyses identified that the ASD group performed significantly worse than matched controls on all measures of cold and hot executive functions (d = 0.54 - 1.5). Hierarchical multiple regression analyses revealed that the ASD sample performed more poorly on emotion recognition and social inference tasks than matched controls after controlling for cold executive functions and employment status. The findings also indicated that the ability to recognize emotions and make social inferences was supported by working memory and response initiation and suppression processes. Overall, this study supports the distinction between hot and cold executive function impairments for adults with ASD. Moreover, it advances understanding of higher-order impairments underlying social interaction difficulties for this population which, in turn, may assist with diagnosis and inform intervention programs.

Prepotent response inhibition and interference control in autism spectrum disorders: two meta-analyses

There is a substantial amount of data providing evidence for, but also against the hypothesis that individuals with autism spectrum disorders (ASD) encounter inhibitory control deficits. ASD is often associated with interference control deficits rather than prepotent response inhibition. Moreover, the developmental trajectory for these inhibitory control processes is hypothesized to differ in ASD as compared to typical development. In efforts to gain a more comprehensive perspective of inhibition in ASD, separate quantitative analysis for prepotent response inhibition studies and interference control studies were conducted. Together, these two meta-analyses included 41 studies with a combined sample size of 1,091 people with ASD (M age 14.8 years), and 1,306 typically developing (TD) controls (M age 13.8 years).The meta-analyses indicated that individuals with ASD show increased difficulties in prepotent response inhibition (effect size 0.55) and in interference control (effect size 0.31). In addition, age was a relevant moderator for prepotent response inhibition but not for interference control. Exploratory analyses revealed that when IQ was taken into account, heterogeneity considerably decreased among interference control studies but not among prepotent response inhibition. In contrast to the general belief, both prepotent response inhibition and interference control problems were observed in individuals with ASD. However, a large variation between studies was also found. Therefore, there remain factors beyond inhibition type, age, or IQ that significantly influence inhibitory control performance among individuals with ASD.

Prefrontal activation during inhibitory control measured by near-infrared spectroscopy for differentiating between autism spectrum disorders and attention deficit hyperactivity disorder in adults

The differential diagnosis of autism spectrum disorders (ASDs) and attention deficit hyperactivity disorder (ADHD) based solely on symptomatic and behavioral assessments can be difficult, even for experts. Thus, the development of a neuroimaging marker that differentiates ASDs from ADHD would be an important contribution to this field. We assessed the differences in prefrontal activation between adults with ASDs and ADHD using an entirely non-invasive and portable neuroimaging tool, near-infrared spectroscopy. This study included 21 drug-naïve adults with ASDs, 19 drug-naïve adults with ADHD, and 21 healthy subjects matched for age, sex, and IQ. Oxygenated hemoglobin concentration changes in the prefrontal cortex were assessed during a stop signal task and a verbal fluency task. During the stop signal task, compared to the control group, the ASDs group exhibited lower activation in a broad prefrontal area, whereas the ADHD group showed underactivation of the right premotor area, right presupplementary motor area, and bilateral dorsolateral prefrontal cortices. Significant differences were observed in the left ventrolateral prefrontal cortex between the ASDs and ADHD groups during the stop signal task. The leave-one-out cross-validation method using mean oxygenated hemoglobin changes yielded a classification accuracy of 81.4% during inhibitory control. These results were task specific, as the brain activation pattern observed during the verbal fluency task did not differentiate the ASDs and ADHD groups significantly. This study therefore provides evidence of a difference in left ventrolateral prefrontal activation during inhibitory control between adults with ASDs and ADHD. Thus, near-infrared spectroscopy may be useful as an auxiliary tool for the differential diagnosis of such developmental disorders.

Executive and visuo-motor function in adolescents and adults with autism spectrum disorder

This study broadly examines executive (EF) and visuo-motor function in 30 adolescent and adult individuals with high-functioning autism spectrum disorder (ASD) in comparison to 28 controls matched for age, gender, and IQ. ASD individuals showed impaired spatial working memory, whereas planning, cognitive flexibility, and inhibition were spared. Pure movement execution during visuo-motor information processing also was intact. In contrast, execution time of reading, naming, and of visuo-motor information processing tasks including a choice component was increased in the ASD group. Results of this study are in line with previous studies reporting only minimal EF difficulties in older individuals with ASD when assessed by computerized tasks. The finding of impaired visuo-motor information processing should be accounted for in further neuropsychological studies in ASD.

Attention deficit hyperactivity disorder symptoms in adults with autism spectrum disorders

Features of attention deficit hyperactivity disorder (ADHD) and impairments on neuropsychological, tests of attention have been documented in children with autism spectrum disorders (ASDs). To date, there has been a lack of research comparing attention in adults with ASD and adults with ADHD. In study 1, 31 adults with ASD and average intellectual function completed self-report measures of ADHD symptoms. These were compared with self-report measures of ADHD symptoms in 38 adults with ADHD and 29 general population controls. In study 2, 28 adults with a diagnosis of ASD were compared with an age- and intelligence quotient-matched sample of 28 adults with ADHD across a range of measures of attention. Study 1 showed that 36.7% of adults with ASD met Diagnostic and Statistical Manual-IV criteria for current ADHD "caseness" (Barkley Current self-report scores questionnaire). Those with a diagnosis of pervasive developmental disorder-not otherwise specified were most likely to describe ADHD symptoms. The ASD group differed significantly from both the ADHD and control groups on total and individual symptom self-report scores. On neuropsychological testing, adults with ASD and ADHD showed comparable performance on tests of selective attention. Significant group differences were seen on measures of attentional switching; adults with ADHD were significantly faster and more inaccurate, and individuals with Asperger's syndrome showed a significantly slower and more accurate response style. Self-reported rates of ADHD among adults with ASD are significantly higher than in the general adult population and may be underdiagnosed. Adults with ASD have attentional difficulties on some neuropsychological measures.

Inhibition in autism: children with autism have difficulty inhibiting irrelevant distractors but not prepotent responses

Resistance to distractor inhibition tasks have previously revealed impairments in children with autism. However, on the classic Stroop task and other prepotent response tasks, children with autism show intact inhibition. These data may reflect a distinction between prepotent response and resistance to distractor inhibition. The current study investigated this possibility using tasks that systematically manipulated inhibitory load. Findings showed that children with autism performed comparably to typically developing and learning disabled controls on a prepotent response inhibition stop-signal task but showed significant inhibitory impairment on a modified flanker resistence to distractor inhibition task. Although the results are clearly consistent with the suggestion that autism is associated with a specific deficit in resistance to distractor inhibition, they may in fact be related to an increased perceptual capacity in autism.

EVENT-RELATED POTENTIAL STUDY OF ATTENTION REGULATION DURING ILLUSORY FIGURE CATEGORIZATION TASK IN ADHD, AUTISM SPECTRUM DISORDER, AND TYPICAL CHILDREN

Autism spectrum disorders (ASD) and attention deficit/hyperactivity disorder (ADHD) are very common developmental disorders which share some similar symptoms of social, emotional, and attentional deficits. This study is aimed to help understand the differences and similarities of these deficits using analysis of dense-array event-related potentials (ERP) during an illusory figure recognition task. Although ADHD and ASD seem very distinct, they have been shown to share some similarities in their symptoms. Our hypothesis was that children with ASD will show less pronounced differences in ERP responses to target and non-target stimuli as compared to typical children, and to a lesser extent, ADHD. Participants were children with ASD (N=16), ADHD (N=16), and controls (N=16). EEG was collected using a 128 channel EEG system. The task involved the recognition of a specific illusory shape, in this case a square or triangle, created by three or four inducer disks. There were no between group differences in reaction time (RT) to target stimuli, but both ASD and ADHD committed more errors, specifically the ASD group had statistically higher commission error rate than controls. Post-error RT in ASD group was exhibited in a post-error speeding rather than corrective RT slowing typical for the controls. The ASD group also demonstrated an attenuated error-related negativity (ERN) as compared to ADHD and controls. The fronto-central P200, N200, and P300 were enhanced and less differentiated in response to target and non-target figures in the ASD group. The same ERP components were marked by more prolonged latencies in the ADHD group as compared to both ASD and typical controls. The findings are interpreted according to the "minicolumnar" hypothesis proposing existence of neuropathological differences in ASD and ADHD, specifically minicolumnar number/width morphometry spectrum differences. In autism, a model of local hyperconnectivity and long-range hypoconnectivity explains many of the behavioral and cognitive deficits present in the condition, while the inverse arrangement of local hypoconnectivity and long-range hyperconnectivity in ADHD explains some deficits typical for this disorder. The current ERP study supports the proposed suggestion that some between group differences could be manifested in the frontal ERP indices of executive functions during performance on an illusory figure categorization task.

Set shifting and working memory in adults with attention-deficit/hyperactivity disorder

Compared to the high number of studies that investigated executive functions (EF) in children with attention-deficit/hyperactivity disorder (ADHD), a little is known about the EF performance of adults with ADHD. This study compared 37 adults with ADHD (ADHD(total)) and 32 control participants who were equivalent in age, intelligence quotient (IQ), sex, and years of education, in two domains of EF--set shifting and working memory. Additionally, the ADHD(total) group was subdivided into two subgroups: ADHD patients without comorbidity (ADHD(-), n = 19) and patients with at least one comorbid disorder (ADHD(+), n = 18). Participants fulfilled two measures for set shifting (i.e., the trail making test, TMT and a computerized card sorting test, CKV) and one measure for working memory (i.e., digit span test, DS). Compared to the control group the ADHD(total) group displayed deficits in set shifting and working memory. The differences between the groups were of medium-to-large effect size (TMT: d = 0.48; DS: d = 0.51; CKV: d = 0.74). The subgroup comparison of the ADHD(+) group and the ADHD(-) group revealed a poorer performance in general information processing speed for the ADHD(+) group. With regard to set shifting and working memory, no significant differences could be found between the two subgroups. These results suggest that the deficits of the ADHD(total) group are attributable to ADHD rather than to comorbidity. An influence of comorbidity, however, could not be completely ruled out as there was a trend of a poorer performance in the ADHD(+) group on some of the outcome measures.