White matter structure in young adults with familial risk for psychosis – The Oulu Brain and Mind Study

• We studied subjects with familial risk for psychosis in a unique birth-cohort setting.
• Participants were in their early adulthood, at the age of high risk for developing schizophrenia.
• There were no differences in white matter microstructure between familial risk and control groups.
• It is possible that white matter abnormalities are not genetically determined features of psychosis.
• Structural disconnectivity may not be a primary sign of psychosis.

According to the disconnectivity model, disruptions in neural connectivity play an essential role in the pathology of schizophrenia. The aim of this study was to determine whether these abnormalities are present in young adults with familial risk (FR) for psychosis in the general population based sample. We used diffusion tensor imaging (DTI) and tract-based spatial statistics to compare whole-brain fractional anisotropy, mean diffusivity, and axial and radial diffusion in 47 (17 males) FR subjects to 51 controls (17 males). All the participants were aged between 20 and 25 years and were members of the Northern Finland Birth Cohort 1986 (Oulu Brain and Mind Study). Region of interest analyses were conducted for 12 tracts. Separately, we analysed whole-brain FA for the subgroup with FR for schizophrenia (n=13) compared with 13 gender-matched controls. Contrary to our expectations there were no differences in any of the DTI measures between FR and control groups. This suggests that white matter abnormalities may not be a genetic feature for risk of psychosis and preceding the onset of a psychotic disorder. Our findings do not support the theory of disconnectivity as a primary sign of psychosis in young adults with FR for the illness.