Schizophrenia polygenic risk score may be a superior forecaster of bipolar disorder (BD) with manic psychosis than of BD with only depressive psychosis or no history of psychosis, according to study results published in Translational Psychiatry.
Researchers assessed 957 participants with BD drawn from the Mayo Clinic Bipolar Biobank for a history of psychosis during manic episodes or psychosis during depressive episodes. Of the 957 participants, 333 individuals had a history of manic psychosis (BD-I), 64 had a history of psychosis only with depression (42 BD-I and 22 BD-II), 547 participants presented with no history of psychosis (312 BD-I and 235 BD-II), and in 13 participants there was insufficient information to determine psychosis history (9 BD-I and 4 BD-II). Only 40 individuals presented with psychosis during mania and depression, and those 40 were assigned to the manic psychosis group for analysis. The researchers constructed polygenic risk scores using the PRSice software and relied on 778 controls.
The schizophrenia polygenic risk score was substantially greater for BD-I cases with manic psychosis than BD-I cases with depressive psychosis (R2=0.021; P =.045), BD-I cases without psychosis (R2=0.015; P =.007), BD-II cases without psychosis (R2=0.014; P =.017), and controls (R2=0.065; P =2 × 10−13).
“Our results show that BD-I with manic psychosis is genetically more similar to [schizophrenia] than any other tested BD subgroup,” researchers concluded, while encouraging further genetic investigation.
One author reports affiliations with the pharmaceutical industry. See the original reference for complete disclosure information.
Markota M, Coombes BJ, Larrabee BR, et al. Association of schizophrenia polygenic risk score with manic and depressive psychosis in bipolar disorder. Transl Psychiatry. 2018; 8:188. doi: 10.1038/s41398-018-0242-3