Constrained spherical deconvolution-based tractography and tract-based spatial statistics show abnormal microstructural organization in Asperger syndrome

Peer reviewe

Abnormal wiring of the connectome in adults with high-functioning autism spectrum disorder

Background: Recent brain imaging findings suggest that there are widely distributed abnormalities affecting the brain connectivity in individuals with autism spectrum disorder (ASD). Using graph theoretical analysis, it is possible to investigate both global and local properties of brain's wiring diagram, i.e., the connectome. Methods: We acquired diffusion-weighted magnetic resonance imaging data from 14 adult males with high-functioning ASD and 19 age-, gender-, and IQ-matched controls. As with diffusion tensor imaging-based tractography, it is not possible to detect complex (e.g., crossing) fiber configurations, present in 60-90 % of white matter voxels; we performed constrained spherical deconvolution-based whole brain tractography. Unweighted and weighted structural brain networks were then reconstructed from these tractography data and analyzed with graph theoretical measures. Results: In subjects with ASD, global efficiency was significantly decreased both in the unweighted and the weighted networks, normalized characteristic path length was significantly increased in the unweighted networks, and strength was significantly decreased in the weighted networks. In the local analyses, betweenness centrality of the right caudate was significantly increased in the weighted networks, and the strength of the right superior temporal pole was significantly decreased in the unweighted networks in subjects with ASD. Conclusions: Our findings provide new insights into understanding ASD by showing that the integration of structural brain networks is decreased and that there are abnormalities in the connectivity of the right caudate and right superior temporal pole in subjects with ASD.Peer reviewe

Physiological responses to affiliation during conversation : Comparing neurotypical males and males with Asperger syndrome

We examined the emotional and psychophysiological underpinnings of social interaction in the context of autism spectrum disorder, more specifically, involving participants diagnosed with Asperger syndrome (AS). We recorded participants’ autonomic nervous system (ANS) activation (electrodermal activity, heart rate, and heart rate variability) and facial muscle activation during conversations in two different types of male dyads: (1) ten dyads where one participant has been diagnosed with AS (AS/NT dyads) and (2) nine dyads where both participants are neurotypical (NT/NT dyads). Afterwards, three independent raters assessed continuously each participant’s affiliative and dominant behaviors during the first and last 10 minutes of the conversations. The relationship between the assessed data and ANS responses was examined. We found that, in the NT/NT dyads, a high level of affiliation displayed by the conversational partner calms down the participant when they are actively dominating the interaction. In contrast, when the participants themselves expressed affiliation, their psychophysiological responses indicated increase in arousal, which suggests that the giving of affiliation is physiologically “hard work.” The affiliation-related ANS responses were similar in those NT participants whose conversational partner had AS, while some differences in facial muscle activation did occur in comparison to NT/NT dyads. In the AS participants, in contrast, a high level of affiliation provided by the conversational partner was associated with increase in arousal, suggesting heightened alertness and stress. As for their own affiliative behavior, the AS participants exhibited similar indicators of alertness and stress as the NT participants, but only when their own level of dominance was low. Our results increase understanding of how individuals with AS experience social interaction at the physiological level, and how this experience differs from that in NT individuals. Moreover, our results confirm and further specify our earlier results, where we proposed that affiliation involves the type of “sharing of the burden” that also reverberates in the participants’ bodies.We examined the emotional and psychophysiological underpinnings of social interaction in the context of autism spectrum disorder, more specifically, involving participants diagnosed with Asperger syndrome (AS). We recorded participants’ autonomic nervous system (ANS) activation (electrodermal activity, heart rate, and heart rate variability) and facial muscle activation during conversations in two different types of male dyads: (1) ten dyads where one participant has been diagnosed with AS (AS/NT dyads) and (2) nine dyads where both participants are neurotypical (NT/NT dyads). Afterwards, three independent raters assessed continuously each participant’s affiliative and dominant behaviors during the first and last 10 minutes of the conversations. The relationship between the assessed data and ANS responses was examined. We found that, in the NT/NT dyads, a high level of affiliation displayed by the conversational partner calms down the participant when they are actively dominating the interaction. In contrast, when the participants themselves expressed affiliation, their psychophysiological responses indicated increase in arousal, which suggests that the giving of affiliation is physiologically “hard work.” The affiliation-related ANS responses were similar in those NT participants whose conversational partner had AS, while some differences in facial muscle activation did occur in comparison to NT/NT dyads. In the AS participants, in contrast, a high level of affiliation provided by the conversational partner was associated with increase in arousal, suggesting heightened alertness and stress. As for their own affiliative behavior, the AS participants exhibited similar indicators of alertness and stress as the NT participants, but only when their own level of dominance was low. Our results increase understanding of how individuals with AS experience social interaction at the physiological level, and how this experience differs from that in NT individuals. Moreover, our results confirm and further specify our earlier results, where we proposed that affiliation involves the type of “sharing of the burden” that also reverberates in the participants’ bodies.Peer reviewe

On the Asperger experience of interaction : Interpersonal dynamics in dyadic conversations

We compared the patterns of affiliative and dominant behavior displayed in male dyads where one participant has Asperger's syndrome (AS) with those displayed in male dyads with two neurotypical (NT) participants. Drawing on interpersonal theory, according to which affiliation and dominance constitute two orthogonal axes of the "interpersonal circle," we used a computer-joystick apparatus to assess the participants' moment-to-moment affiliative and dominant behaviors throughout conversation. The patterns of affiliation and dominance were subsequently studied in relation to post-conversation questionnaires that targeted the interactional experiences of the participants in the two different types of dyads (AS dyads, NT dyads). We found the overall interpersonal notion of complementarity to hold for AS and NT dyads alike: greater affiliation in one participant invoked greater affiliation in the co-participant, and greater dominance invoked greater submissiveness in the co-participant. The AS and NT dyads, however, differed with regard to how affiliative and dominant behaviors related to each other during the time course of a single conversation. Furthermore, we found important differences between the AS and NT dyads in how the different patterns of affiliation and dominance were experienced by the participants. For example, a high level of affiliation synchrony was experienced in more negative terms by the participants in the AS dyads than by those in the NT dyads, while a high level of dominance coordination was experienced in more positive terms by the participants in the AS dyads than by those in the NT dyads. The paper increases understanding of the details of the interactional deficits associated with AS and of the conditions in which AS participants may get maximally positive interactional experiences. More generally, our study highlights the necessity to take the study of individual differences in the experiences of patterns of affiliation and dominance into the official agenda of empirical interaction research.Peer reviewe

Insomnia is a frequent finding in adults with Asperger syndrome

BACKGROUND: Asperger syndrome (AS) is a neurodevelopmental disorder belonging to autism spectrum disorders with prevalence rate of 0,35% in school-age children. It has been most extensively studied in childhood while there is scarcity of reports concerning adulthood of AS subjects despite the lifelong nature of this syndrome. In children with Asperger syndrome the initiation and continuity of sleep is disturbed because of the neuropsychiatric deficits inherent of AS. It is probable that sleep difficulties are present in adulthood as well. Our hypothesis was that adults with AS suffer from difficulty in initiating and maintaining sleep and nonrestorative sleep (insomnia). METHODS: 20 AS without medication were compared with 10 healthy controls devoid of neuropsychiatric anamnesis. Clinical examination, blood test battery and head MRI excluded confounding somatic illnesses. Structured psychiatric interview for axis-I and axis-II disorders were given to both groups as well as Beck Depression Inventory and Wechsler adult intelligence scale, revised version. Sleep quality was assessed with sleep questionnaire, sleep diary during 6 consecutive days and description of possible sleep problems by the participants own words was requested. RESULTS: compared with controls and with normative values of good sleep, AS adults had frequent insomnia. In sleep questionnaire 90% (18/20), in sleep diary 75% (15/20) and in free description 85% (17/20) displayed insomnia. There was a substantial psychiatric comorbidity with only 4 AS subject devoid of other axis-I or axis-II disorders besides AS. Also these persons displayed insomnia. It can be noted that the distribution of psychiatric diagnoses in AS subjects was virtually similar to that found among patient with chronic insomnia. CONCLUSIONS: the neuropsychiatric deficits inherent of AS predispose both to insomnia and to anxiety and mood disorders. Therefore a careful assessment of sleep quality should be an integral part of the treatment plan in these individuals. Conversely, when assessing adults with chronic insomnia the possibility of autism spectrum disorders as one of the potential causes of this condition should be kept in mind

Subjective face recognition difficulties, aberrant sensibility, sleeping disturbances and aberrant eating habits in families with Asperger syndrome

BACKGROUND: The present study was undertaken in order to determine whether a set of clinical features, which are not included in the DSM-IV or ICD-10 for Asperger Syndrome (AS), are associated with AS in particular or whether they are merely a familial trait that is not related to the diagnosis. METHODS: Ten large families, a total of 138 persons, of whom 58 individuals fulfilled the diagnostic criteria for AS and another 56 did not to fulfill these criteria, were studied using a structured interview focusing on the possible presence of face recognition difficulties, aberrant sensibility and eating habits and sleeping disturbances. RESULTS: The prevalence for face recognition difficulties was 46.6% in individuals with AS compared with 10.7% in the control group. The corresponding figures for subjectively reported presence of aberrant sensibilities were 91.4% and 46.6%, for sleeping disturbances 48.3% and 23.2% and for aberrant eating habits 60.3% and 14.3%, respectively. CONCLUSION: An aberrant processing of sensory information appears to be a common feature in AS. The impact of these and other clinical features that are not incorporated in the ICD-10 and DSM-IV on our understanding of AS may hitherto have been underestimated. These associated clinical traits may well be reflected by the behavioural characteristics of these individuals