Alpár Alexandru Lázár1, Andrea Bíró2, Miklós Győri 3, Zsanett Tárnok2, Júlia Gádoros2, Péter Halász4, Róbert Bódizs1

1 Institute of Behavioural Sciences, Semmelweis University Budapest, Budapest, Hungary

2 Research center, Vadaskert Child Psychiatry Hospital, Budapest, Hungary

3 Dept. of Cognitive Psychology, Institute of Psychology, ELTE University, Budapest, Hungary

4 Neurology, National Institute of Neurology and Psychiatry, Budapest, Hungary

Background: There is a growing number of studies reporting an altered sleep pattern in subjects with autism spectrum disorders, respectively the modification of spindling activity. This might reflect a region-specific modification of thalamocortical organization. This would be in accordance with the reported morphological brain differences encountered in this group of patients. Sleep spindles (SP) were shown recently to reflect general and specific cognitive abilities.

Methods: We pursued a two consecutive night polysomnographic examination of 16 subjects with Asperger syndrome (AS) and 14 controls matched for age, gender and nonverbal IQ. We used a 10 channel EEG montage with linked mastoids reference. We calculated the absolute power spectra of the following bandwidths for the whole night NREM sleep: slow oscillation (0,5-1,25 Hz), delta (1-4 Hz), slow (11-13,5 Hz) and fast (13,5-15 Hz) SP. We also measured thedensity of both type of SP.

Results:We found and increased absolute power spectra of slow oscillation (P<0,02), delta (P<0,01) and fast SP (P<0,03) over the left temporal area and a decreased fast SP density (P<0,05) over the right occipital area in the AS group.

Conclusions: The increased power spectra of the previously mentioned bandwidths over the left temporal area could reflect the reliance upon verbal coding of subjects with AS. The decreased fast SP density over the right occipital area might be related to abnormalities of visual processing and also to the right hemisphere dysfunction reported in AS. The results suggest a possible region-specific modification of thalamocortical organization in AS.

Supported by Hungarian Scientific Research Fund