A holistic approach to fragile X syndrome integrated guidance for person-centred care.

BACKGROUND: The Fragile X community has expressed a desire for centralised, national guidelines in the form of integrated guidance for Fragile X Syndrome (FXS). METHODS: This article draws on existing literature reviews, primary research and clinical trials on FXS, a Fragile X Society conference workshop and first-hand experience of clinicians who have worked with those living with FXS over many years. RESULTS: The article scopes proposed integrated guidance over the life course, including appendices of symptoms, comorbidities and referral options for FXS and Fragile X Premutation Associated Conditions. CONCLUSION: Integrated guidance would provide an authoritative source for doctors, health professionals, therapists, care workers, social workers, educators, employers, families and those living with FXS, so that a holistic, person-centred approach can be taken across the United Kingdom to garner the best outcomes for those with FXS.

Predictors of psychotic symptoms among young people with special educational needs.

BACKGROUND: Psychotic symptoms and psychotic disorders occur at increased rates in adults with intellectual disability, including borderline intellectual functioning, compared with the general population. Little is known about the development of such symptoms in this population.AimsTo examine whether clinical factors predictive of psychotic disorder in a familial study of schizophrenia also apply to those with intellectual disability. METHOD: Adolescents with special educational needs (SEN) were assessed with the Structured Interview for Schizotypy (SIS) and Childhood Behavioural Checklist (CBCL). These scores were used to prospectively divide participants based on their anticipated risk for psychotic disorder. A subsample were reassessed three times over 6 years, using the Positive and Negative Syndrome Scale (PANSS). RESULTS: The SEN group were more symptomatic than controls throughout (Cohen's d range for PANSS subscale scores: 0.54-1.4, all P < 0.007). Over 6 years of follow-up, those above the SIS and CBCL cut-off values at baseline were more likely than those below to display morbid positive psychotic symptoms (odds ratio, 3.5; 95% CI 1.3-9.0) and develop psychotic disorder (odds ratio, 11.4; 95% CI 2.6-50.1). Baseline SIS and CBCL cut-off values predicted psychotic disorder with sensitivity of 0.67, specificity of 0.85, positive predictive value of 0.26 and negative predictive value of 0.97. CONCLUSIONS: Adolescents with SEN have increased psychotic and non-psychotic symptoms. The personality and behavioural features associated with later psychotic disorder in this group are similar to those in people with familial loading. Relatively simple screening measures may help identify those in this vulnerable group who do and do not require monitoring for psychotic symptoms.Declaration of interestNone.

Negative symptoms and longitudinal grey matter tissue loss in adolescents at risk of psychosis: preliminary findings from a 6-year follow-up study.

BACKGROUND: Negative symptoms are perhaps the most disabling feature of schizophrenia. Their pathogenesis remains poorly understood and it has been difficult to assess their development over time with imaging techniques. AIMS: To examine, using tensor-based structural imaging techniques, whether there are regions of progressive grey matter volume change associated with the development of negative symptoms. METHOD: A total of 43 adolescents at risk of psychosis were examined using magnetic resonance imaging and whole brain tensor-based morphometry at two time points, 6 years apart. RESULTS: When comparing the individuals with significant negative symptoms with the remaining participants, we identified five regions of significant grey matter tissue loss over the 6-year period. These regions included the left temporal lobe, the left cerebellum, the left posterior cingulate and the left inferior parietal sulcus. CONCLUSIONS: Negative symptoms are associated with longitudinal grey matter tissue loss. The regions identified include areas associated with psychotic symptoms more generally but also include regions uniquely associated with negative symptoms.

Visual social attention in SYNGAP1-related intellectual disability.

SYNGAP1-ID is a neurodevelopmental disorder caused by a mutation of the SYNGAP1 gene. Characterized by moderate to severe developmental delay, it is associated with several physical and behavioral issues as well as additional diagnoses, including autism. However, it is not known whether social cognitive differences seen in SYNGAP1-ID are similar to those previously identified in idiopathic or other forms of autism. This study therefore investigated visual social attention in SYNGAP1-ID. Eye movements were recorded across three passive viewing tasks (face scanning, pop-out, and social preference) of differing social complexity in 24 individuals with SYNGAP1-ID and 12 typically developing controls. We found that SYNGAP1-ID participants looked at faces less than the controls, and when they did look at faces, they had less time looking at and fewer fixations to the eyes. For the pop-out task, where social and nonsocial objects (Phone, car, face, bird, and face-noise) were presented in an array, those with SYNGAP1-ID spent significantly less time looking at the phone stimulus as well as fewer fixations to the face compared with the typically developing controls. When looking at two naturalistic scenes side by side, one social in nature (e.g., with children present) and the other not, there were no differences between the SYNGAP1-ID group and typically developing controls on any of the examined eye tracking measures. This study provides novel findings on the social attention of those with SYNGAP1-ID and helps to provide further evidence for using eye tracking as an objective measure of the social phenotype in this population in future clinical trials.

The Behavioral Profile of SYNGAP1-Related Intellectual Disability.

This study aimed to describe the behavioral profile of individuals with SYNGAP1-ID. Parents/carers of 30 individuals aged 3-18 years old with a diagnosis of SYNGAP1-ID and 21 typically developing individuals completed the Vineland-3 Adaptive Behavior Scale and the Child Behavior Checklist. We found that those with SYNGAP1-ID showed fewer adaptive behaviors and higher levels of internalizing and externalizing behaviors across almost all domains compared to typically developing controls. There was some evidence that these differences were greatest in older children, and more apparent in those with co-occuring epilepsy. This characterization of the phenotype of SYNGAP1-ID significantly aids our understanding of the behavioral profile of this population and is a step towards the development of tailored interventions.

Profiling Autism and Attention Deficit Hyperactivity Disorder Traits in Children with SYNGAP1-Related Intellectual Disability.

SYNGAP1-related ID is a genetic condition characterised by global developmental delay and epilepsy. Individuals with SYNGAP1-related ID also commonly show differences in attention and social communication/interaction and frequently receive additional diagnoses of Autism Spectrum Disorder (ASD) or Attention Deficit Hyperactivity Disorder (ADHD). We thus set out to quantify ASD and ADHD symptoms in children with this syndrome. To assess ASD and ADHD, parents and caregivers of a child with SYNGAP1-related ID (N = 34) or a typically developing control (N = 21) completed the Social Responsiveness Scale-2, the Social Communication Questionnaire with a subset of these also completing the Conners-3. We found that those with SYNGAP1-related ID demonstrated higher levels of autistic traits on both the SRS and SCQ than typically developing controls. On the SRS, those with SYNGAP1-related ID scored highest for restricted repetitive behaviours, and were least impaired in social awareness. On the Conners-3, those with SYNGAP1-related ID also showed a high prevalence of ADHD traits, with scores demonstrating difficulties with peer relations but relatively low occurrence of symptoms for DSM-5 conduct disorder and DSM-5 oppositional defiant disorder. Hierarchical clustering analysis highlighted distinct SYNGAP1-related ID subgroups for both ASD and ADHD traits. These findings provide further characterisation of the SYNGAP1-related ID behavioural phenotype, guiding diagnosis, assessment and potential interventions.

A systematic review of the utility of 1.5 versus 3 Tesla magnetic resonance brain imaging in clinical practice and research.

OBJECTIVE: MRI at 3 T is said to be more accurate than 1.5 T MR, but costs and other practical differences mean that it is unclear which to use. METHODS: We systematically reviewed studies comparing diagnostic accuracy at 3 T with 1.5 T. We searched MEDLINE, EMBASE and other sources from 1 January 2000 to 22 October 2010 for studies comparing diagnostic accuracy at 1.5 and 3 T in human neuroimaging. We extracted data on methodology, quality criteria, technical factors, subjects, signal-to-noise, diagnostic accuracy and errors according to QUADAS and STARD criteria. RESULTS: Amongst 150 studies (4,500 subjects), most were tiny, compared old 1.5 T with new 3 T technology, and only 22 (15 %) described diagnostic accuracy. The 3 T images were often described as "crisper", but we found little evidence of improved diagnosis. Improvements were limited to research applications [functional MRI (fMRI), spectroscopy, automated lesion detection]. Theoretical doubling of the signal-to-noise ratio was not confirmed, mostly being 25 %. Artefacts were worse and acquisitions took slightly longer at 3 T. CONCLUSION: Objective evidence to guide MRI purchasing decisions and routine diagnostic use is lacking. Rigorous evaluation accuracy and practicalities of diagnostic imaging technologies should be the routine, as for pharmacological interventions, to improve effectiveness of healthcare. KEY POINTS : • Higher field strength MRI may improve image quality and diagnostic accuracy. • There are few direct comparisons of 1.5 and 3 T MRI. • Theoretical doubling of the signal-to-noise ratio in practice was only 25 %. • Objective evidence of improved routine clinical diagnosis is lacking. • Other aspects of technology improved images more than field strength.

EEG as a translational biomarker and outcome measure in fragile X syndrome.

Targeted treatments for fragile X syndrome (FXS) have frequently failed to show efficacy in clinical testing, despite success at the preclinical stages. This has highlighted the need for more effective translational outcome measures. EEG differences observed in FXS, including exaggerated N1 ERP amplitudes, increased resting gamma power and reduced gamma phase-locking in the sensory cortices, have been suggested as potential biomarkers of the syndrome. These abnormalities are thought to reflect cortical hyper excitability resulting from an excitatory (glutamate) and inhibitory (GABAergic) imbalance in FXS, which has been the target of several pharmaceutical remediation studies. EEG differences observed in humans also show similarities to those seen in laboratory models of FXS, which may allow for greater translational equivalence and better predict clinical success of putative therapeutics. There is some evidence from clinical trials showing that treatment related changes in EEG may be associated with clinical improvements, but these require replication and extension to other medications. Although the use of EEG characteristics as biomarkers is still in the early phases, and further research is needed to establish its utility in clinical trials, the current research is promising and signals the emergence of an effective translational biomarker.

Clinical and behavioural features of SYNGAP1-related intellectual disability: a parent and caregiver description.

BACKGROUND: SYNGAP1-related intellectual disability (ID) is a recently described neurodevelopmental disorder that is caused by pathogenic variation in the SYNGAP1 gene. To date, the behavioural characteristics of this disorder have mainly been highlighted via the prevalence of existing diagnoses in case series. We set out to detail the behavioural features of this disorder by undertaking interviews with those who have a child with SYNGAP1-related ID to allow them to describe their child's behaviour. METHODS: We conducted 27 semi-structured interviews with parents and caregivers which covered basic information (e.g., age, gender), family history, perinatal history, past medical history, developmental history, epilepsy, behavioural history, and a general description of their child's behaviour. RESULTS: Using a mixed quantitative and qualitative approach, the responses from the parents indicated that those with SYNGAP1-related ID showed high rates of autism spectrum disorder (52%), difficulties with fine and gross motor skills, delays in language development, and a high prevalence of epilepsy (70%). A qualitative analysis highlighted their general behaviour affected the themes of daily living skills, distress-related behaviours, emotional regulation, difficulties with change, a lack of danger awareness, and sensory differences. Sensory features described involved auditory, visual, tactile, gustatory, and proprioceptive themes. CONCLUSIONS: Our findings and behavioural descriptions provide important insights as well as implications for the diagnosis and care of those with SYNGAP1-related ID.

"A Group of Fellow Travellers Who Understand": Interviews With Autistic People About Post-diagnostic Peer Support in Adulthood.

Receiving a diagnosis of autism in adulthood can be a life changing event, impacting identity, relationships, and mental health. A lack of post-diagnostic support has been highlighted by autistic adults, their allies, clinicians, and service providers. It can be a source of distress for autistic adults, reinforcing feelings of social isolation and rejection. Peer support could be a cost-effective, flexible, and sustainable model to provide community-based support for autistic adults. However, there is little research on the value of peer support, despite calls from the autistic community. This qualitative study explored autistic experiences and needs post-diagnosis, identifying specific ways that peer support may benefit them, and exploring the limitations of peer support. Twelve autistic adults who had all received an autism diagnosis in adulthood completed a semi-structured interview focussing on the diagnostic experience, post-diagnostic support needed and provided, engagement with the autistic community, and post-diagnostic peer support. Thematic analysis of interview transcripts resulted in four themes: (1) Mismatch in support needed and provided; (2) Community connection; (3) Flexible and personalised support; and (4) Sustainability. Participants indicated that peer support may be a useful mechanism to support autistic adults' post-diagnosis and offers unique opportunities not available through other support channels. Though informal peer support exists, it could be more sustainable and effective if well-supported and funded.

A functional MRI facial emotion-processing study of autism in individuals with special educational needs.

This study aimed to investigate the functional imaging associations of autism in individuals with special educational needs and demonstrate the feasibility of such research. The study included 18 individuals (3 female,15 male; mean age 24.3; mean IQ 69.7) with special educational needs (SEN), of whom 9 met criteria for autism. The task examined the Blood-oxygen-level dependant response to fearful and neutral faces. Individuals in the autism group had 2 clusters of significantly reduced activity centred on the left superior frontal gyrus and left angular gyrus compared to those with SEN alone in response to the fearful faces. In the response to neutral faces, individuals in the autism group also had a cluster of significantly greater activity centred on the right precentral gyrus compared to those with SEN alone. We suggest that autistic characteristics in individuals with SEN are associated with changes in fearful facial emotion processing analogous to those previously reported in autistic individuals without SEN, and who are of average or above average cognitive ability. The finding of enhanced response to neutral facial stimuli needs further investigation, although we speculate this may relate to reports of the experience of 'hyper-mentalisation' in social situations as reported by some autistic individuals.

Impact of cannabis use on thalamic volume in people at familial high risk of schizophrenia.

BACKGROUND: No longitudinal study has yet examined the association between substance use and brain volume changes in a population at high risk of schizophrenia. AIMS: To examine the effects of cannabis on longitudinal thalamus and amygdala-hippocampal complex volumes within a population at high risk of schizophrenia. METHOD: Magnetic resonance imaging scans were obtained from individuals at high genetic risk of schizophrenia at the point of entry to the Edinburgh High-Risk Study (EHRS) and approximately 2 years later. Differential thalamic and amygdala-hippocampal complex volume change in high-risk individuals exposed (n = 25) and not exposed (n = 32) to cannabis in the intervening period was investigated using repeated-measures analysis of variance. RESULTS: Cannabis exposure was associated with bilateral thalamic volume loss. This effect was significant on the left (F = 4.47, P = 0.04) and highly significant on the right (F= 7.66, P= 0.008). These results remained significant when individuals using other illicit drugs were removed from the analysis. CONCLUSIONS: These are the first longitudinal data to demonstrate an association between thalamic volume loss and exposure to cannabis in currently unaffected people at familial high risk of developing schizophrenia. This observation may be important in understanding the link between cannabis exposure and the subsequent development of schizophrenia.

Genetic variation in CNTNAP2 alters brain function during linguistic processing in healthy individuals.

Language impairments are a characteristic feature of autism and related autism spectrum disorders (ASDs). Autism is also highly heritable and one of the most promising candidate genes implicated in its pathogenesis is contactin-associated protein-like 2 (CNTNAP2), a gene also associated with language impairment. In the current study we investigated the functional effects of variants of CNTNAP2 associated with autism and language impairment (rs7794745 and rs2710102; presumed risk alleles T and C, respectively) in healthy individuals using functional magnetic resonance imaging (fMRI) during performance of a language task (n = 66). Against a background of normal performance and lack of behavioral abnormalities, healthy individuals with the putative risk allele versus those without demonstrated significant increases in activation in the right inferior frontal gyrus (Broca's area homologue) and right lateral temporal cortex. These findings demonstrate that risk associated variation in the CNTNAP2 gene impacts on brain activation in healthy non-autistic individuals during a language processing task providing evidence of the effect of genetic variation in CNTNAP2 on a core feature of ASDs.

Sleep Abnormalities in the Synaptopathies-SYNGAP1-Related Intellectual Disability and Phelan-McDermid Syndrome.

Neurodevelopmental disorders are frequently associated with sleep disturbances. One class of neurodevelopmental disorders, the genetic synaptopathies, is caused by mutations in genes encoding proteins found at the synapse. Mutations in these genes cause derangement of synapse development and function. We utilized a validated sleep instrument, Children's Sleep Habits Questionnaire (CSHQ) to examine the nature of sleep abnormalities occurring in individuals with two synaptopathies-Phelan-McDermid syndrome (PMD) (N = 47, male = 23, female = 24, age 1-46 years) and SYNGAP1-related intellectual disability (SYNGAP1-ID) (N = 64, male = 31, female = 33, age 1-64 years), when compared with unaffected siblings (N = 61, male = 25, female = 36, age 1-17 years). We found that both PMD and SYNGAP1-ID have significant sleep abnormalities with SYNGAP1-ID having greater severity of sleep disturbance than PMD. In addition, sleep disturbances were more severe for PMD in individuals 11 years and older compared with those less than 11 years old. Individuals with either disorder were more likely to use sleep aids than unaffected siblings. In conclusion, sleep disturbances are a significant phenotype in the synaptopathies PMD and SYNGAP1-ID. Improved sleep is a viable endpoint for future clinical trials for these neurodevelopmental disorders.

Glutamate and functional connectivity - support for the excitatory-inhibitory imbalance hypothesis in autism spectrum disorders.

It has been proposed that the Glutamate (Glu) system is implicated in autism spectrum disorders (ASD) via an imbalance between excitatory and inhibitory brain circuits, which impacts on brain function. Here, we investigated the excitatory-inhibitory imbalance theory by measuring Glu-concentrations and the relationship with resting-state function. Nineteen adult males with ASD and 19 age and sex-matched healthy controls (HC) (23 - 58 years) underwent Proton Magnetic Resonance Spectroscopy of the dorsal anterior cingulate cortex (dACC) and resting-state functional Magnetic Resonance Imaging (fMRI). Glu and Glx concentrations were compared between groups. Seed-based functional connectivity was analyzed with a priori seeds of the right and left dACC. Finally, metabolite concentrations were related to functional connectivity coefficients and compared between both groups. Individuals with ASD showed significantly negative associations between increased Glx concentrations and reduced functional connectivity between the dACC and insular, limbic and parietal regions. In contrast, HC displayed a positive relationship between the same metabolite and connectivity measures. We provided new evidence to support the excitatory-inhibitory imbalance theory, where excitatory Glx concentrations were related to functional dysconnectivity in ASD. Future research is needed to investigate large-scale functional networks in association with both excitatory and inhibitory metabolites in subpopulations of ASD.

Categorical and Dimensional Approaches to Examining the Joint Effect of Autism and Schizotypal Personality Disorder on Sustained Attention.

INTRODUCTION: Accumulating evidence for the co-occurrence autism spectrum disorder (ASD) and schizotypal personality disorder (SPD) at both the diagnostic and symptom levels raises important questions about the nature of their association and the effect of their co-occurrence on the individual's phenotype and functional outcome. Research comparing adults with ASD and SPD, as well as the impact of their co-occurrence on outcomes is extremely limited. We investigated executive functioning in terms of response inhibition and sustained attention, candidate endophenotypes of both conditions, in adults with ASD, SPD, comorbid ASD and SPD, and neurotypical adults using both categorical and dimensional approaches. METHODS: A total of 88 adults (Mean Age = 37.54; SD = 10.17): ASD (n = 26; M/F = 20/6); SPD (n = 20; M/F = 14/6); comorbid ASD and SPD (n=9; M/F=6/3) and neurotypicals (n=33; M/F=23/10) completed the Sustained Attention to Response Task (SART) in both its fixed and random forms. Positive and autistic symptom severity was assessed with the positive subscale of the Positive and Negative Syndrome Scale (PANSSpos) and the PANSS Autism Severity Score (PAUSS), respectively. RESULTS: Controlling for full scale IQ, working memory and medication dosage, group analyses revealed that the comorbid group committed fewer omission errors than the ASD group on the fixed SART, and fewer omission errors than the ASD and SPD groups on the random SART. The individual difference analyses of the entire sample revealed that the PANSSpos and PAUSS interactively reduced omission errors in both the fixed and random SARTs, as well as increased d' scores, indicative of improved overall performance. We observed no significant results for commission errors or reaction time. CONCLUSIONS: Concurrent elevated levels of autistic and positive psychotic symptoms seem to be associated with improved sustained attention abilities (reduced omission errors) but not inhibition (commission errors). Our findings highlight the importance of investigating the concurrent effect of ASD and SPD at both the symptom and diagnostic levels, and raise important questions for future research regarding the clinical and behavioral phenotypes of adults with dual diagnosis and, more generally, about the nature of the relationship between ASD and SPD.

Structural abnormalities of ventrolateral and orbitofrontal cortex in patients with familial bipolar disorder.

OBJECTIVES: Abnormalities of ventral prefrontal function have been widely reported in bipolar disorder, but reports of structural abnormalities in the same region are less consistent. We examined the presence and location of ventral prefrontal abnormalities in a large sample of individuals with bipolar disorder and their relationship to gender, psychotic symptoms, and age. METHODS: Structural magnetic resonance imaging brain scans were carried out on 66 individuals with bipolar disorder, type I, and 66 controls. Voxel-based morphometry was used to examine differences in grey and white matter density between the groups and their relationship with a lifetime occurrence of psychotic symptoms and age. RESULTS: Reductions in grey matter density were seen in the left and right lateral orbital gyri and the right inferior frontal gyrus, while white matter density reductions were seen in the corona radiata and the left temporal stem. In contrast, hallucinations and positive symptoms were associated with grey matter reduction in the left middle temporal gyrus. Age was more strongly associated with the right inferior frontal gyrus grey matter reductions in the bipolar group than in the controls, but not with any other finding. CONCLUSION: Abnormalities of the ventral prefrontal cortex are likely to be involved in the aetiopathology of bipolar disorder, while hallucinations appear to be more closely associated with temporal lobe abnormality, extending earlier work in schizophrenia. Further prospective studies are required to comprehensively address the trajectory of these findings.

Autism in Fragile X Syndrome; A Functional MRI Study of Facial Emotion-Processing.

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and autism spectrum disorder, and among those with fragile X syndrome, approximately 1/3rd meet a threshold for an autism spectrum disorder (ASD) diagnosis. Previous functional imaging studies of fragile X syndrome have typically focused on those with fragile X syndrome compared to either neurotypical or autism spectrum disorder control groups. Further, the majority of previous studies have tended to focus on those who are more intellectually able than is typical for fragile X syndrome. In this study, we examine the impact of autistic traits in individuals with fragile X syndrome on a paradigm looking at facial emotion processing. The study included 17 individuals with fragile X syndrome, of whom 10 met criteria for autism as measured by the Autism Diagnostic Observation Schedule (ADOS). Prior to the scan, participants rehearsed on a mock scanner to help acclimatize to the scanner environment and thus allow more severely affected individuals to participate. The task examined the blood-oxygen-level-dependent (BOLD) response to fearful and neutral faces taken from the Ekman faces series. Individuals in the autism group had a region of significantly reduced activity centered on the left superior temporal gyrus, compared to those with FXS alone, in response to the fearful faces. We suggest that autism in individuals with fragile X syndrome is associated with similar changes in the neurobiology of facial emotion processing as seen in idiopathic autism.

Decreased functional brain response to emotional arousal and increased psychiatric symptomology in FMR1 premutation carriers.

The FMR1 premutation is an expansion of the CGG repeat island in the FMR1 gene to between 55 and 200 repeats. Evidence suggests that as well as conferring risk for neurodegeneration, the premutation is also associated with increased risk for autistic traits and psychiatric symptoms. An emotional processing fMRI task was used to examine the response to a change in emotional arousal in 17 male carriers and 17 matched controls. A psychiatric symptom checklist (SCL-90-R), autism spectrum and empathy quotients (AQ and EQ), and the Ekman Faces Test were used to investigate clinical symptoms and emotional processing. Carriers exhibited significantly lower activation compared to controls at the bilateral superior parietal lobe, bilateral Brodmann Area (BA) 17 (V1), right intraparietal area and right BA18 (V2) when comparing high and low arousal conditions. Group by age analyses were not significant. Assessments revealed that carriers displayed significantly worse symptoms of psychiatric symptoms and higher levels of autistic traits, as well as impaired facial emotion recognition. No measurements revealed an association with age. Here, we show significantly altered emotional processing in carriers which display stability over age, suggesting that, unlike degenerative aspects, emotional symptoms may be consistent over the lifespan in carriers.

Towards a neuroanatomy of autism: a systematic review and meta-analysis of structural magnetic resonance imaging studies.

BACKGROUND: Structural brain abnormalities have been described in autism but studies are often small and contradictory. We aimed to identify which brain regions can reliably be regarded as different in autism compared to healthy controls. METHOD: A systematic search was conducted for magnetic resonance imaging studies of regional brain size in autism. Data were extracted and combined using random effects meta-analysis. The modifying effects of age and IQ were investigated using meta-regression. RESULTS: The total brain, cerebral hemispheres, cerebellum and caudate nucleus were increased in volume, whereas the corpus callosum area was reduced. There was evidence for a modifying effect of age and IQ on the cerebellar vermal lobules VI-VII and for age on the amygdala. CONCLUSIONS: Autism may result from abnormalities in specific brain regions and a global lack of integration due to brain enlargement. Inconsistencies in the literature partly relate to differences in the age and IQ of study populations. Some regions may show abnormal growth trajectories.