Premorbid functioning in schizophrenia spectrum disorders with comorbid substance use: A systematic review.

Premorbid functioning has been related with several clinical features and prognosis of schizophrenia spectrum disorders. Comorbidity with substance use is highly prevalent and usually hinders clinical improvement in this kind of psychiatric disorders. This systematic review analyzes the differences in the premorbid functioning of subjects with a schizophrenia spectrum disorder with substance use (SSD+, dual psychosis) or without it (SSD-). A systematic review (PRISMA guidelines), including search in electronic databases (MEDLINE, Web of Science, and Cochrane Library), was performed. 118 published works were considered of which only 20 met our inclusion criteria. Although there is a great variability in methodologies, diagnoses included, and substances used, studies using the Premorbid Functioning Scale to assess the academic and/or social domains found that SSD+ subjects had a poorer academic but better social premorbid functioning than those with SSD-. Current evidence is not conclusive, so additional studies are required to integrate intervening factors in order to clarify the clinical implications of premorbid functioning to improve the course and therapeutic response of patients.