Prefrontal cortex gyrification index in twins: an MRI study

Cortical development and folding seems to be under environmental as well as genetic control. The aim of our study was to estimate the genetic influence on gyrification and cortical volumes, comparing prefrontal gyrification index (GI) in monozygotic (MZ) and dizygotic (DZ) twin pairs, and unrelated pairs. Twenty-four subjects (6 pairs of MZ and 6 pairs of DZ twins) were included in this study. Prefrontal cortical folding (gyrification) was measured by an automated and manual version of the gyrification index (A-GI, M-GI) according to previously published protocols. MR-imaging was performed and 3 representative slices were selected from coronar MR-imaging scans. The volumes of the total brain, temporal lobes, prefrontal lobes, and cerebellum were analyzed, too. To evaluate similarity in GI, absolute differences in GI, and brain volumes as well as intraclass correlations of twin pairs were compared with regard to twin status. Finally, a control group of unrelated pairs was assembled from the first two study groups and analyzed. Compared to unrelated pairs, twin pairs exhibited more similarity concerning different brain volumes and a trend to more similarity concerning A-GI. MZ twins did not present more similarity concerning GI (automatically and manually measured) and volume measurements compared to DZ twins. Different factors, like intrauterine factors, postnatal development conditions, and especially environmental factors might account for the differences between related and unrelated pairs. The nonexistence of a pronounced similarity in MZ twins compared to DZ twins concerning prefrontal GI raises questions about the extent of genetic influence on GI

Regionally Specific White Matter Disruptions of Fornix and Cingulum in Schizophrenia

Limbic circuitry disruptions have been implicated in the psychopathology and cognitive deficits of schizophrenia, which may involve white matter disruptions of the major tracts of the limbic system, including the fornix and the cingulum. Our study aimed to investigate regionally specific abnormalities of the fornix and cingulum in schizophrenia using diffusion tensor imaging (DTI). We determined the fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) profiles along the fornix and cingulum tracts using a fibertracking technique and a brain mapping algorithm, the large deformation diffeomorphic metric mapping (LDDMM), in the DTI scans of 33 patients with schizophrenia and 31 age-, gender-, and handedness-matched healthy controls. We found that patients with schizophrenia showed reduction in FA and increase in RD in bilateral fornix, and increase in RD in left anterior cingulum when compared to healthy controls. In addition, tract-based analysis revealed specific loci of these white matter differences in schizophrenia, that is, FA reductions and AD and RD increases occur in the region of the left fornix further from the hippocampus, FA reductions and RD increases occur in the rostral portion of the left anterior cingulum, and RD and AD increases occur in the anterior segment of the left middle cingulum. In patients with schizophrenia, decreased FA in the specific loci of the left fornix and increased AD in the right cingulum adjoining the hippocampus correlated with greater severity of psychotic symptoms. These findings support precise disruptions of limbic-cortical integrity in schizophrenia and disruption of these structural networks may contribute towards the neural basis underlying the syndrome of schizophrenia and clinical symptomatology

Neural correlates of “social gaze” processing in high-functioning autism under systematic variation of gaze duration

AbstractDirect gaze is a salient nonverbal signal for social interest and the intention to communicate. In particular, the duration of another's direct gaze can modulate our perception of the social meaning of gaze cues. However, both poor eye contact and deficits in social cognitive processing of gaze are specific diagnostic features of autism. Therefore, investigating neural mechanisms of gaze may provide key insights into the neural mechanisms related to autistic symptoms. Employing functional magnetic resonance imaging (fMRI) and a parametric design, we investigated the neural correlates of the influence of gaze direction and gaze duration on person perception in individuals with high-functioning autism (HFA) and a matched control group. For this purpose, dynamically animated faces of virtual characters, displaying averted or direct gaze of different durations (1s, 2.5s and 4s) were evaluated on a four-point likeability scale. Behavioral results revealed that HFA participants showed no significant difference in likeability ratings depending on gaze duration, while the control group rated the virtual characters as increasingly likeable with increasing gaze duration. On the neural level, direct gaze and increasing direct gaze duration recruit regions of the social neural network (SNN) in control participants, indicating the processing of social salience and a perceived communicative intent. In participants with HFA however, regions of the social neural network were more engaged by averted and decreasing amounts of gaze, while the neural response for processing direct gaze in HFA was not suggestive of any social information processing

Autism Spectrum Disorders in Adulthood: Clinical and Neuropsychological Findings of Aspergers Syndrome Diagnosed Late in Life

High-functioning autism (HFA) and Aspergers syndrome (AS) are autism spectrum disorders (ASD) characterised by disturbances in social interaction, both verbal and non-verbal communication and repetitive and/or restrictive behaviour since early childhood. Symptoms appear generally during early childhood and adolescence. The increasing need to clarify diagnostic queries in advanced age led to the constitution of specialised outpatient clinics for adults involving a growing amount of HFA/AS subjects diagnosed late in life. However, thus far neuropsychological data about this group are scarce.We present a subgroup of 39 patients with HFA/AS (mean age at diagnosis 31.1 ± 8.9 years) who were consecutively diagnosed at the autism outpatient clinic at the Department of Psychiatry at the University Hospital Cologne. Autistic symptoms (autism spectrum quotient; AQ), depressive symptoms (Beck depression inventory; BDI), general intelligence (HAWIE-R), social cognition ("theory of mind", ToM) and executive functioning (COWAT) were systematically studied in comparison to a control group matched for age, education, gender and intelligence (n = 39).HFA/AS subjects presented higher AQ scores (40.4 ± 5.2) as opposed to the healthy controls (13.5 ± 4.8). Neuropsychologically, patients showed deficits in social cognition, executive functions and in subtests of HAWIE-R related to verbal comprehension and perceptual organisation as opposed to the healthy control group.The diagnosis of autistic disorders in adulthood basically relies on the clinical assessment of autistic core symptoms which were corroborated by high AQ values. The self-rating instrument AQ was found to be highly discriminative between the HFA/AS group and the healthy control group. The neuropsychological profile of adult HFA/AS patients diagnosed late in life is compatible with that of previously investigated HFA/AS populations. These findings show that such basic autism-associated deficits persist until adulthood, although patients are able to learn social rules

Brief Report: Preferred Processing of Social Stimuli in Autism: A Perception Task

In this study we investigate whether persons with autism spectrum disorder (ASD) perceive social images differently than control participants (CON) in a graded perception task in which stimuli emerged from noise before dissipating into noise again. We presented either social stimuli (humans) or non-social stimuli (objects or animals). ASD were slower to recognize images during their emergence, but as fast as CON when indicating the dissipation of the image irrespective of its content. Social stimuli were recognized faster and remained discernable longer in both diagnostic groups. Thus, ASD participants show a largely intact preference for the processing of social images. An exploratory analysis of response subsets reveals subtle differences between groups that could be investigated in future studies

Imaging derived cortical thickness reduction in high-functioning autism: key regions and temporal slope

Cortical thickness (CT) changes possibly contribute to the complex symptomatology of autism. The aberrant developmental trajectories underlying such differences in certain brain regions and their continuation in adulthood are a matter of intense debate. We studied 28 adults with high-functioning autism (HFA) and 28 control subjects matched for age, gender, IQ and handedness. A surface-based whole brain analysis utilizing FreeSurfer was employed to detect CT differences between the two diagnostic groups and to investigate the time course of age-related changes. Direct comparison with control subjects revealed thinner cortex in HFA in the posterior superior temporal sulcus (pSTS) of the left hemisphere. Considering the time course of CT development we found clusters around the pSTS and cuneus in the left and the paracentral lobule in the right hemisphere to be thinner in HFA with comparable age-related slopes in patients and controls. Conversely, we found clusters around the supramarginal gyrus and inferior parietal lobule (IPL) in the left and the precentral and postcentral gyrus in the right hemisphere to be thinner in HFA, but with different age-related slopes in patients and controls. In the latter regions CT showed a steady decrease in controls but no analogous thinning in HFA. CT analyses contribute in characterizing neuroanatomical correlates of HFA. Reduced CT is present in brain regions involved in social cognition. Furthermore, our results demonstrate that aberrant brain development leading to such differences is proceeding throughout adulthood. Discrepancies in prior morphometric studies may be induced by the complex time course of cortical changes

Brief Report: Preferred Processing of Social Stimuli in Autism: A Perception Task

In this study we investigate whether persons with autism spectrum disorder (ASD) perceive social images differently than control participants (CON) in a graded perception task in which stimuli emerged from noise before dissipating into noise again. We presented either social stimuli (humans) or non-social stimuli (objects or animals). ASD were slower to recognize images during their emergence, but as fast as CON when indicating the dissipation of the image irrespective of its content. Social stimuli were recognized faster and remained discernable longer in both diagnostic groups. Thus, ASD participants show a largely intact preference for the processing of social images. An exploratory analysis of response subsets reveals subtle differences between groups that could be investigated in future studies

Das psychosoziale Funktionsniveau spätdiagnostizierter PatientInnen mit hochfunktionalem Autismus im Erwachsenenalter.

The first time diagnosis of autism spectrum disorder (ASD) after passing childhood and adolescence is still considered a rare event. However, in recent years an increasing demand for diagnostic clarifications with suspected ASD in adulthood challenges this view. There is insufficient knowledge about the neuropsychological characterisation and psychosocial outcome of this adult subgroup in the autistic spectrum.To determine the psychosocial functioning (living status, partnerships, level of education, psychiatric history) of adult patients with late diagnosed ASD.In a retrospective study, a chart review was conducted on 178 consecutively diagnosed individuals at a specialised outpatient clinic for adults with ASD. Global ratings of psychosocial functioning, assessment of psychiatric history and neuropsychological and psychopathological investigations were evaluated.The majority of patients (92 %) diagnosed with ASD suffered from high-functioning autism (HFA)/Asperger syndrome (AS) according to the criteria of ICD-10 (F84.5). The gender ratio was 2:1 favouring males. Mean age at diagnosis (34.1 ± 9.5 years), general intelligence (HAWIE-R, global-IQ 115 ± 20) and self-rated autistic symptoms (autism spectrum quotient [AQ] 39 ± 6) were not discriminative to gender. The psychiatric history revealed a lifetime consultation rate of 78 %, most frequently with depression (50 %). The self-report instrument Beck depression inventory (BDI) identified 30 % of individuals presenting with depressive symptoms in clinical relevant intensity (BDI > 17). Achievement of an independent living status was reported by 68 % of individuals, 58 % reported about current or past intimate partnerships and almost two-thirds of the patients had achieved a higher educational status.The majority of ASD diagnosed late in lifetime turned out to be HFA/AS, presenting with high psychosocial adjustment with regard to independent living, educational status and partnerships. The high level of global intelligence supports the hypothesis of cognitively compensated autistic disturbances leading to the diagnosis comparably late in lifetime. The lifetime rate of psychiatric consultations is high, reflecting the importance to consider a diagnosis of ASD even late in life