Psychotic depression and bipolar disorder are sometimes lumped together as the “affective psychoses.” Among the mood disorders, these two have a stronger biological basis, although environmental causes still contribute to their risk. In a meta-analysis of 68 studies (Rodriguez V et al, Schizophr Bull 2021 Jan 22:sbaa197), 6 environmental risk factors stood out as statistically significant; they are pictured with their odds ratio in the figure at right (an odds ratio of 2 suggests a 2-fold higher risk). Missing is maternal infection, which is a known risk for schizophrenia but had mixed results in affective psychoses. Overall, the risk factors that contribute to schizophrenia are similar to those identified here, suggesting common causative pathways. The strongest risk is also the one that is most preventable: substance misuse. Note that the study included non-psychotic bipolar disorder with the “affective psychoses.”

Chart: Environmental Risk Factors for Affective Psychosis

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