Functional outcome in major psychiatric disorders and associated clinical and psychosocial variables: A potential cross-diagnostic phenotype for further genetic investigations?

Objectives. Functional outcome has recently become of interest for cross-diagnostic subphenotype approaches in psychiatric genetics. Therefore, it is crucial to know about clinical, demographic and psychosocial variables that correlate with long-term functioning. Unfortunately, there is a lack of studies that directly compare the importance of correlates for functional outcome between different disorders. Methods. Applying regression models to samples of patients with schizophrenia (SZ, n = 238), bipolar disorder (BD, n = 533) and major depressive disorder (MDD, n = 398), we compared the magnitude of association of potential correlates with functional outcome, measured by the Global Assessment of Functioning (GAF) score. Results. Shared correlates for worse functional outcome were poor premorbid functioning, insidious illness onset and poor premorbid work or social adjustment in all three disorders, and negative symptomatology in SZ and BD. Disorder-specific correlates for SZ were longer duration of illness, lower functioning during episodes and being life-time single, for BD substance abuse and suicidality, and for MDD premorbid unemployment and having a premorbid personality disorder. Conclusions. We found different patterns of correlates for long-term functioning in SZ, BD and MDD. Knowledge of these patterns may improve the quality of genetic investigations focussing on functional outcome.