Antti Mustonen

Cannabis use is increasing worldwide and also certain European countries plan to legalize or decriminalize cannabis. This will further increase use rates and also result into higher number of people with cannabis use disorder. Cannabis use in persons with severe mental disorders, namely schizophrenia-spectrum disorders, bipolar disorders and major depressive disorder, has been reported to adversely impact on illness course and associate with non-adherence to treatments. However, impacts of cannabis use disorder on long-term treatment outcomes in severe mental disorders are not known.  The overall aim of this project is to investigate long-term treatment pathways and outcomes of patients with severe mental disorder and comorbid cannabis use disorder, to help in designing optimal health care for these patients. We aim to investigate healthcare service and medication use and work disability during first five years of illness, compared to patients with severe mental disorder without cannabis use disorder. We will also investigate risk of mortality and effectiveness of medications associated with decreased risk of illness relapse, and mortality. Finally, we will develop a prediction model for adverse clinical outcomes to help clinical practice to inform which patients are at the highest risk and in need of enhanced monitoring and effective interventions. Further, we will investigate whether treatment can be tailored based on the predicted risk level.