Cognitive impairments in psychotic disorders, including schizophrenia and bipolar disorder, are influenced by both disease-specific factors and general factors, such as education and childhood adversity, with the extent of influence varying by diagnosis, according to a recent study.
Researchers investigated how general risk factors and diagnosis-specific effects contribute to cognitive impairment in psychotic disorders. The cross-sectional study included 3,370 participants from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (BSNIP) studies across six sites. The participants included 840 healthy controls, 709 participants with schizophrenia, 541 with schizoaffective disorder, 457 with bipolar I disorder with psychosis, 823 relatives of patients, and their mean age was 37.9 years, with 56% being female. Importantly, the inclusion of relatives aimed to study intermediate phenotypes, which reflect both genetic and environmental factors that contribute to cognitive impairment in these disorders.
Published in JAMA Psychiatry, the study utilized machine learning, specifically extreme gradient boosting regression, and Shapley additive explanations to assess the relationship between various exposures—such as age, sex, education, childhood adversity, and antipsychotic use—and cognitive performance. Cognitive function was measured using the Brief Assessment of Cognition in Schizophrenia.
The results showed that participants with schizophrenia experienced the most significant cognitive impairment, with a mean cognitive composite score reduction of 1.4 standard deviations (SD) compared with controls. Participants with schizoaffective disorder had a reduction of 1.2 SD, while those with bipolar I disorder with psychosis showed a smaller reduction of 0.5 SD. Relatives of patients also demonstrated cognitive deficits, suggesting that both genetic and environmental risk factors contribute to cognitive impairment. Diagnosis-specific factors contributed to a portion of the impairment (schizophrenia, −0.29 SD; schizoaffective disorder, −0.15 SD; bipolar I disorder, −0.13 SD). However, non-disease-specific factors, such as educational attainment and childhood adversity, explained a larger portion of the cognitive deficits (schizophrenia, −0.73 SD; schizoaffective disorder, −0.64 SD; bipolar I disorder, −0.13 SD). Antipsychotic use was associated with a similar deficit across diagnostic groups (schizophrenia, −0.37 SD; schizoaffective disorder, −0.33 SD; bipolar I disorder, −0.26 SD).
Full disclosures can be found in the published study.
