Polygenic Risk Assessment for Schizophrenia in Patients with Nonpsychotic Disorders and Attenuated Symptoms of Psychosis: A Pilot Study

Abstract

Background: significant contribution of genetic factors in the development of schizophrenia is a generally recognized fact. Polygenic risk index for schizophrenia turned out to be an effective tool allowing to draw a dividing line between schizophrenia and mentally healthy control in terms of genetics. Objective: to assess the predictive ability of the polygenic risk score for schizophrenia (SZ-PRS) in adolescent patients with a first depressive episode and attenuated psychotic symptoms (APS). Patients and Methods: sixty adolescent inpatient with a first depressive episode were examined. Based on the presence of APS at admission, patients were divided into two groups: a group with APS and a group without APS. Subgroups of patients in the first group were identified through follow-up observations: those with psychosis manifestation and/or low social functioning and those without manifestation and with high social functioning. Whole-genome genotyping was performed for all participants, and SZ-PRS were calculated. For comparison, a group of patients diagnosed with schizophrenia (n = 879) and a group of mentally healthy individuals (n = 759), who had previously undergone whole-genome genotyping and had their SZ-PRS calculated, were used. Results: SZ-PRS of the APS group occupy an intermediate position between the healthy control and schizophrenia patients, significantly differing from each of them. The group without APS did not differ from the control group, but compared to the group of schizophrenia patients, the SZ-PRS in this group was significantly lower. Comparing subgroups of patients showed that the SZ-PRS in the APS group without psychosis manifestation and social functioning impairment was significantly lower than in the group with schizophrenia manifestation. The APS subgroups with psychosis manifestation and with functioning impairment did not differ significantly from each other or from the schizophrenia group. Conclusion: the results obtained for the first time for the russian population showed that SZ-PRS can be considered as a tool for assessing the risk of developing psychosis or reduced social functioning in patients with APS.