Corpus callosum size in adults with high-functioning autism and the relevance of gender.

The goal of the study was to investigate the size of the corpus callosum (CC) and its subsegments in relation to total brain volume (TBV) as an empirical indicator of impaired connectivity in autism with special respect to gender. In MRI data sets of 29 adults with high-functioning autism (HFA) and 29 age-, gender- and IQ-matched control subjects, the TBV was measured and the CC was analyzed as a whole and in subsegments employing two different manual segmentation procedures. With respect to diagnosis, there were no significant differences in the dependent variables (CC, CC subsegments, and TBV). With respect to gender, only TBV was significantly increased in males compared with females, resulting in a significantly decreased CC/TBV ratio in males. This finding, however, was independent from gender and can be fully attributed to brain size. Our findings do not support the following hypotheses: (1) a hypothesis of impaired CC in HFA adults as a subgroup of patients with autism spectrum disorders, and (2) the sexual dimorphism hypothesis of the CC.

Dissociation between key processes of social cognition in autism: impaired mentalizing but intact sense of agency.

Deficits in social cognition and interaction, such as in mentalizing and imitation behavior, are hallmark features of autism spectrum disorders. Both imitation and mentalizing are at the core of the sense of agency, the awareness that we are the initiators of our own behavior. Little evidence exists regarding the sense of agency in autism. Thus, we compared high-functioning adults with autism to healthy control subjects using an action monitoring and attribution task. Subjects with autism did not show deficits in this task, yet they showed significant mentalizing deficits. Our findings indicate a dissociation between the sense of agency and ascription of mental states in autism. We propose that social-cognitive deficits in autism may arise on a higher level than that of action monitoring and awareness.

Sex-Related Cognitive Profile in Autism Spectrum Disorders Diagnosed Late in Life: Implications for the Female Autistic Phenotype.

Females with high-functioning ASD are known to camouflage their autistic symptoms better than their male counterparts, making them prone to being under-ascertained and delayed in diagnostic assessment. Thus far the underlying cognitive processes that enable such successful socio-communicative adaptation are not well understood. The current results show sex-related differences in the cognitive profile of ASD individuals, which were diagnosed late in life exclusively. Higher verbal abilities were found in males (n = 69) as opposed to higher processing speed and better executive functions in females with ASD (n = 38). Since both sexes remained unidentified during childhood and adolescence, these results are suggestive for sex-distinctive cognitive strategies as an alternative to typically-developed reciprocal social behavior and social mimicry in high functioning ASD.

The investigation and differential diagnosis of Asperger syndrome in adults.

BACKGROUND: As a result of the increased public interest in autism spectrum disorders (ASD), certain core manifestations of ASD--impaired social interaction and communication, bizarre interests--are now commonly recognized as being typical of autism, not only in children, but in adults as well. More often than before, general practitioners, neurologists, and psychiatrists find themselves being asked whether a patient is suffering from previously unrecognized Asperger syndrome (AS). The prevalence of ASD is estimated at 1%, and the ratio of diagnosed to undiagnosed cases at about 3:2. Little is known about the diagnostic evaluation of AS in adulthood. METHOD: We selectively searched the Medline database for pertinent literature, paying special attention to diagnostic manuals and to the guideline of the United Kingdom's National Institute for Health and Care Excellence (NICE). RESULTS: Centrally important aspects of the diagnosis of AS include an assessment of the patient's ability to assume the emotional perspectives of others, non-verbal modes of expression, repetitive behavior patterns, and childhood social behavioral history. The autism quotient (AQ) is now established as a simple but nonspecific screening test. Up to 70% of all affected adults have comorbid disturbances, most often depression and anxiety disorders. The differential diagnosis includes personality disorders, anxiety disorders, obsessive-compulsive disorder, and attention deficit-hyperactivity disorder. The diagnostic assessment should proceed in stepwise fashion, starting from simple screening in primary care and then moving on to evaluation of the suspected diagnosis by a mental health care specialist, followed by extensive further investigation in an outpatient clinic specifically devoted to patients with autism spectrum disorders. CONCLUSION: The diagnostic assessment of autism in adults requires knowledge of the core and accompanying manifestations of autism and of their differential diagnoses. More research is needed for the development of further screening tests and the precise determination of diagnosis rates, differential diagnoses, nd comorbidities.

Responses to nonverbal behaviour of dynamic virtual characters in high-functioning autism.

We investigated feelings of involvement evoked by nonverbal behaviour of dynamic virtual characters in 20 adults with high-functioning autism (HFA) and high IQ as well as 20 IQ-matched control subjects. The effects of diagnostic group showed that subjects with autism experienced less "contact" and "urge" to establish contact across conditions and less "interest" than controls in a condition with meaningful facial expressions. Moreover, the analyses within groups revealed that nonverbal behaviour had less influence on feelings in HFA subjects. In conclusion, disturbances of HFA subjects in experiencing involvement in social encounters with virtual characters displaying nonverbal behaviour do not extend to all kinds of feelings, suggesting different pathways in the ascription of involvement in social situations.