Increased Brain Cortical Folding in Individuals at Risk of Psychosis

Poster B57, Friday, October 21, 11:30 am - 1:00 pm, Le Baron

Daiki Sasabayashi1, Yoichiro Takayanagi1, Shinsuke Koike2, Hidenori Yamasue2, Naoyuki Katagiri3, Atsushi Sakuma4, Mihoko Nakamura1, Tsutomu Takahashi1, Kazunori Matsumoto4, Masafumi Mizuno3, Kiyoto Kasai2, Michio Suzuki1; 1Toyama University, 2Tokyo University, 3Toho University, 4Tohoku University

1.Purpose: Within the context of a neurodevelopmental model in schizophrenia, abnormalities of brain cortical folding are regarded as a possible marker of early neurodevelopment. Investigating changes of gyrification in prodromal state might be useful for predicting the onset of psychotic illness. However, there are few previous neuroimaging studies of cortical folding in individuals with at-risk mental state (ARMS). To identify robust brain structural abnormalities in ARMS with a large sample size, we designed a multicenter study. 2.Materials and Methods: T1-weighted magnetic resonance imaging scans were obtained by using 1.5-T or 3-T scanners from 104 ARMS individuals, and 106 healthy controls subjects at four different scanning sites. ARMS subjects were followed regularly to confirm whether or not they subsequently developed overt psychosis. Using FreeSurfer software, local gyrification index (LGI) of the entire cortex was compared between the groups. Age, sex and the scanning site were controlled in the general linear models. 3.Results: Compared with the controls, ARMS individuals showed significantly higher LGI in a wide range of regions dominantly on the right hemisphere. Of 104 ARMS individuals, 21 developed overt psychosis. ARMS individuals who later developed psychosis showed significantly higher LGI in the left occipital regions compared with the individuals who did not. 4.Conclusion: Our finding of aberrant left occipital gyrification has important implications for underlying neurobiologic features of emerging florid psychosis. In addition, increased gyrification index suggesting a broad range of brain hypergyria seen in ARMS individuals could be potential candidates for vulnerability markers for the development of psychosis.

Topic Area: Neuroimaging

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