Tobacco use moderates associations between cannabis use, psychiatric symptoms, and cognitive performance in psychosis spectrum disorders

Tobacco and cannabis use are highly prevalent among individuals with psychotic disorders. Tobacco use has been consistently linked to poorer clinical and cognitive outcomes, whereas findings regarding cannabis use remain mixed. The present study was a secondary analysis of cross-sectional data from the Bipolar-Schizophrenia Network on Intermediate Phenotypes 2, a large multi-site psychosis spectrum sample with cognitive and clinical assessments. The primary aim was to more precisely characterize how tobacco or cannabis use, co-use, and non-use differentially relate to clinical and cognitive function. The final sample included 884 individuals with psychotic disorders without diagnosis of substance abuse in the past 30 days or substance dependence in the past 3 months for any substance except tobacco. Among individuals with psychosis, tobacco-only users demonstrated greater symptom burden and worse cognitive impairment than several comparison psychosis substance groups. In contrast, cannabis use showed more nuanced associations. Greater adult cannabis use was tied to worse general psychopathology for current tobacco users but fewer general symptoms among those who never used tobacco. More adult cannabis use was linked to better cognitive performance for current tobacco users but was not linked to working memory among past tobacco users. These findings highlight tobacco use as a potential marker of greater disease severity and cognitive impairment among individuals with psychosis, while also demonstrating the importance of considering patterns of co-occurring use of substances.