S85. INDIVIDUALS WITH POSITIVE AND NEGATIVE SCHIZOTYPY EXHIBIT A REVERSED PATTERN OF THALAMIC-CEREBELLAR BRAIN CONNECTIVITY

Abstract

Background: The cerebellum is structurally and functionally connected with the cerebral cortex and limbic circuits and plays an important role in high level cognitive functions. Abnormalities of cerebellar connections have been observed in clinical samples including autism and schizophrenia. Increased volumes of lateral ventricle and pallidum together with a reduction in hippocampus, amygdala, thalamus, accumbens and intracranial volumes have been found in large-scale analyses of schizophrenia patients from the ENIGMA schizophrenia Working Group (van Erp et al., 2016). Reduction of total cerebellar grey matter volume in schizophrenia patients was also observed in a multisite mega-analysis (Moberget et al., 2017). In the present study we aimed to investigate the subcortical volumes and cerebellar grey matter volumes, as well as their structural covariance in individuals with schizotypy. Method(s): Six samples consisting of 352 valid participants (mean age, 19.8 years; range, 16-28 years; 41.5% male) from 4 imaging centers were included. The T1 weighted brain images were preprocessed using the FreeSurfer software v6.0 (http://www.freesurfer.net) and SUIT toolbox (http://www.diedrichsenlab.org/imaging/suit.htm) for the calculation of subcortical volumes and cerebellar volumes, respectively. Both the Schizotypal Personality Questionnaire (SPQ) and the Chapman scales (including Social Anhedonia Scale and Physical Anhedonia Scale) were used to measure the dimensional schizotypy. We split the participants into high schizotypy according to commonly used criteria (top 10%, total score>=36 for high SPQ group, n=56; >=MEAN+1SD for high Social Anhedonia group, n=88) and low schizotypy groups ( < 0.05) and pallidum (r = -0.37, p < 0.001) in the low schizotypy group. For the high Social Anhedonia group, we found a consistent negative correlation between cerebellar grey matter volumes and thalamus (r = -0.23, p < 0.05). However, no such correlation was found in the high SPQ group. Discussion(s): Although several studies have examined the brain structural changes associated with schizotypy, few have focused on the unique changes concerning the different dimensions of schizotypy. Individuals with high negative schizotypy were found to exhibit local structural changes in the caudate and the cerebellum while maintaining an intact thalamic-cerebellar connection. However, individuals with high positive schizotypy exhibited relative intact local brain volumes but disrupted thalamic-cerebellar connection. These findings provide further evidence to support different patterns of structural brain changes associated with positive and negative dimensions of schizotypy. Indeed, our results suggest that cerebellar volumes as well as thalamic-cerebellar connections may serve as risk indicators for psychosis.