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Query: UMLS:C0004352 (autism)
 32,579 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous research has revealed a lack of planum temporale (PT) asymmetry in adults with autism. This finding is now extended to children and adolescents with the disorder. MRI scans were obtained from 12 children with autism and 12 gender, handedness and age-matched comparison participants. The volume of gray matter in the PT and Heschl's gyrus (HG) in both hemispheres was measured. PT volume was larger in the left hemisphere than in the right in the comparison, but not the autism group. This specifically reflected reduced volume of the left PT in the autism group. There were noted differences in the overall morphological appearance of the right Sylvian fissure in the autism group, but no volumetric difference in the right PT. No differences in HG volumes were observed between the two groups. Lack of PT asymmetry may suggest an early neurodevelopmental disturbance in autism.
J Autism Dev Disord 2005 Aug
PMID:Planum temporale volume in children and adolescents with autism. 1613 33

Studies addressing etiologic yield in childhood developmental disabilities have mainly looked at individuals with developmental delay/mental retardation. The few studies addressing the question of etiologic yield in patients with pervasive developmental disorders (PDDs) had a major drawback, in that the enrolled subjects were diagnosed as having the autistic spectrum disorders based only on history and clinical examination, and/or on unspecified instruments. In addition, only some of these patients underwent a complete laboratory evaluation. To investigate the etiologic yield of PDDs, we undertook a large prospective study on subjects selected according to very strict criteria and diagnosed as having PDD based on the present "gold standard" (ADI-R and ADOS-G), and a clinical diagnosis made by a child psychiatrist. Eighty-five (85) patients with PDD and their first degree relatives participated in this study. These patients were selected from a sample of 236 subjects who had received a clinical diagnosis of PDD at the Stella Maris Institute between March 2002 and 2005. Selection criteria for entering the study were: (1) a diagnosis of PDD (with exclusion of the Rett syndrome) confirmed after the administration of the ADI-R (autism diagnostic interview-revised) and the ADOS-G (autism diagnostic observation schedule-generic). In addition, a clinical diagnosis was made by the child psychiatrist, on the basis of presence or absence of DSM-IV symptoms of autism; (2) chronological age between 4 and 18 years; (3) IQ>30; (4) availability of both biologic parents. Patients, 65/85 (76.5%), had autism, 18/85 (21.2%) had PDD-NOS, and the remaining 2/85 (2.3%) had Asperger syndrome. Ages varied between 4 years 2 months and 12 years 5 months (mean 7.6 years), and there was a marked male preponderance (68/85). All subjects underwent various laboratory studies and neuroimaging. With respect to possible etiologic determination, a detailed history and physical examination in this group of patients with PDD was informative in 10.5% (9/85). HRB karyotype was diagnostic in one, and molecular fragile X studies in one child. Brain MRI was informative in two children (2.3%) with relative macrocrania but no neurological features; and EEG was helpful in one child, identifying a Landau-Kleffner disorder. Audiometry and brainstem auditory evoked potentials (BAEPs) showed a bilateral sensorineural loss in another child. Metabolic evaluation gave normal results in all subjects. The results suggest an evaluation paradigm with reference to etiologic determination for individuals with PDDs that does not presently justify metabolic or neuroimaging on a screening basis. Recurrence risk, treatment implications, and significant and long-lasting emotional relief for the parents suggest that serious consideration be given to clinical genetic examination, genetic testing, EEG study (during wakefulness and sleep), and audiometry, despite a relatively low yield.
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PMID:Etiologic yield of autistic spectrum disorders: a prospective study. 1641 94

To assess the frequency of cryptic subtelomeric rearrangements in children and adolescents with autism spectrum disorders, blood samples were studied using a complete set of subtelomeric FISH probes in 72 children with autism spectrum disorders. All children had normal high resolution karyotype, DNA fra-X analysis, brain MRI, metabolic work-up, and physical/neurological examination. Subtelomeric analysis did not detect abnormalities in any of the subjects, suggesting the uselessness of such investigations in individuals with primary autism spectrum disorders.
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PMID:The yield of subtelomeric FISH analysis in the evaluation of autistic spectrum disorders. 1641 95

While individuals with autism spectrum disorders (ASD) are typically impaired in interpreting the communicative intent of others, little is known about the neural bases of higher-level pragmatic impairments. Here, we used functional MRI (fMRI) to examine the neural circuitry underlying deficits in understanding irony in high-functioning children with ASD. Participants listened to short scenarios and decided whether the speaker was sincere or ironic. Three types of scenarios were used in which we varied the information available to guide this decision. Scenarios included (i) both knowledge of the event outcome and strong prosodic cues (sincere or sarcastic intonation), (ii) prosodic cues only or (iii) knowledge of the event outcome only. Although children with ASD performed well above chance, they were less accurate than typically developing (TD) children at interpreting the communicative intent behind a potentially ironic remark, particularly with regard to taking advantage of available contextual information. In contrast to prior research showing hypoactivation of regions involved in understanding the mental states of others, children with ASD showed significantly greater activity than TD children in the right inferior frontal gyrus (IFG) as well as in bilateral temporal regions. Increased activity in the ASD group fell within the network recruited in the TD group and may reflect more effortful processing needed to interpret the intended meaning of an utterance. These results confirm that children with ASD have difficulty interpreting the communicative intent of others and suggest that these individuals can recruit regions activated as part of the normative neural circuitry when task demands require explicit attention to socially relevant cues.
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PMID:Neural basis of irony comprehension in children with autism: the role of prosody and context. 1648 75

The 'amygdala theory of autism' suggests a crucial role for the amygdala in the neurobiological basis of autism spectrum disorders. However, to date evidence is lacking of a direct relationship between amygdala measures and behavioral manifestations of autism in affected individuals. In 17 adult individuals with Asperger syndrome (AS) and 17 well-matched controls we therefore assessed associations between MRI-derived amygdala volume and behavioral variables of emotion recognition and social cognition, as well as with core AS symptomatology. Results revealed that individuals with AS exhibited impairments in emotion recognition and social cognition compared to controls and also showed atypical relationships between amygdala volumes and overall head size. We found positive associations between emotional and social understanding and amygdala volume in the control group, but not in the AS group. In the AS group however, amygdala size was negatively related to diagnostic parameters, with smaller amygdala volumes involving higher levels of restricted-repetitive behavior domains. Our data seem to indicate that in AS the amygdala is not crucially involved in social and emotional understanding. It may, however, be a mediator for narrow interest patterns and the imposition of routines and rituals. Our data, in conjunction with current literature, seem to argue for a modification of the 'amygdala theory of autism'.
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PMID:The 'amygdala theory of autism' revisited: linking structure to behavior. 1656 49

The objective of this investigation was to examine the existence of minor physical anomalies (MPA) in autism. The interorbital and interlens distances were measured on MRI scans obtained from a sample of 40 non-mentally retarded individuals with autism and 41 healthy controls. No differences were observed between the two groups on any measurements. However, when the analysis was conducted using a split median procedure, individuals with autism and either low FSIQ, PIQ, or VIQ had shorter interorbital distances when compared to controls. Hypotelorism is a MPA that may be present in a subgroup of individuals with autism. Additional research is warranted using large sample sizes with a wide range of intellectual functioning.
J Autism Dev Disord 2006 Jul
PMID:An MRI study of minor physical anomalies in autism. 1660 27

The normal pattern of cerebral asymmetry may be altered in neurodevelopmental disorders such as autism and schizophrenia. Babies born very preterm have an increased risk of brain damage, and brain abnormalities which persist into adolescence. This study aimed to ascertain whether preterm birth affects the development of fronto-occipital asymmetry. Structural MRI (magnetic resonance imaging) scans from 14 year old individuals born very preterm (n = 61; mean age 14 years 11 months; 29 male) and age-matched full-term controls (n = 49; mean age 14 years 11 months; 31 male) underwent morphometric analysis, using well-validated stereological methods. Measurements of right and left prefrontal, premotor, sensorimotor and occipitoparietal regional volumes were made and asymmetry indices calculated. These factors underwent a reductive factor analysis. There were no significant between-group differences in fronto-occipital asymmetry between the preterm adolescents and their full-term counterparts. It seems unlikely, therefore, that preterm birth per se deviates the development of normal fronto-occipital asymmetry. Neonatal periventricular haemorrhage with ventricular dilatation revealed by ultrasound may be associated with reversal of asymmetry in the sensorimotor area.
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PMID:Cerebral asymmetry in 14 year olds born very preterm. 1669 55

Autism is a neurodevelopmental disorder with a range of clinical presentations. These presentations vary from mild to severe and are referred to as autism spectrum disorders. The most common clinical sign of autism spectrum disorders is social interaction impairment, which is associated with verbal and non-verbal communication deficits and stereotyped and repetitive behaviors. Thanks to recent brain imaging studies, scientists are getting a better idea of the neural circuits involved in autism spectrum disorders. Indeed, functional brain imaging, such as positron emission tomography, single foton emission tomography and functional MRI have opened a new perspective to study normal and pathological brain functioning. Three independent studies have found anatomical and rest functional temporal lobe abnormalities in autistic patients. These alterations are localized in the superior temporal sulcus bilaterally, an area which is critical for perception of key social stimuli. In addition, functional studies have shown hypoactivation of most areas implicated in social perception (face and voice perception) and social cognition (theory of mind). These data suggest an abnormal functioning of the social brain network in autism. The understanding of the functional alterations of this important mechanism may drive the elaboration of new and more adequate social re-educative strategies for autistic patients.
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PMID:[Autism: neuroimaging]. 1679 88

Based on evidence for thalamic abnormalities in autism, impairments of thalamocortical pathways have been suspected. We examined the functional connectivity between thalamus and cerebral cortex in terms of blood oxygen level dependent (BOLD) signal cross-correlation in 8 male participants with high-functioning autism and matched normal controls, using functional MRI during simple visuomotor coordination. Both groups exhibited widespread connectivity, consistent with known extensive thalamocortical connectivity. In a direct group comparison, overall more extensive connectivity was observed in the autism group, especially in the left insula and in right postcentral and middle frontal regions. Our findings are inconsistent with the hypothesis of general underconnectivity in autism and instead suggest that subcortico-cortical connectivity may be hyperfunctional, potentially compensating for reduced cortico-cortical connectivity.
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PMID:Partially enhanced thalamocortical functional connectivity in autism. 1682 63

Comprehending high-imagery sentences like The number eight when rotated 90 degrees looks like a pair of eyeglasses involves the participation and integration of several cortical regions. The linguistic content must be processed to determine what is to be mentally imaged, and then the mental image must be evaluated and related to the sentence. A theory of cortical underconnectivity in autism predicts that the interregional collaboration required between linguistic and imaginal processing in this task would be underserved in autism. This functional MRI study examined brain activation in 12 participants with autism and 13 age- and IQ-matched control participants while they processed sentences with either high- or low-imagery content. The analysis of functional connectivity among cortical regions showed that the language and spatial centres in the participants with autism were not as well synchronized as in controls. In addition to the functional connectivity differences, there was also a group difference in activation. In the processing of low-imagery sentences (e.g. Addition, subtraction and multiplication are all math skills), the use of imagery is not essential to comprehension. Nevertheless, the autism group activated parietal and occipital brain regions associated with imagery for comprehending both the low and high-imagery sentences, suggesting that they were using mental imagery in both conditions. In contrast, the control group showed imagery-related activation primarily in the high-imagery condition. The findings provide further evidence of underintegration of language and imagery in autism (and hence expand the understanding of underconnectivity) but also show that people with autism are more reliant on visualization to support language comprehension.
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PMID:Sentence comprehension in autism: thinking in pictures with decreased functional connectivity. 1683 47


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