Substance Use Disorders and Comorbid Mental Illness: A Focus on Epidemiological Data Regarding Mood and Anxiety Disorders

Substance use disorders (SUDs) and mental illness frequently co-occur. Cross-sectional studies indicate that mood and anxiety disorders occur at higher rates among individuals with SUDs and that increased prevalence of SUDs are found among those with mood and anxiety disorders. Specific rates of comorbidity differ depending on the specific SUD and mental illness in question. Longitudinal studies have reported mixed results regarding the temporal association between SUDs and mood and anxiety disorders. Among all mood and anxiety disorders, bipolar disorder seems to be particularly associated with the future development of SUDs. This chapter focuses on the epidemiological data regarding the comorbidity of SUDs and mood and anxiety disorders, presenting a summary of cross-sectional and longitudinal research on the topic. The authors conclude by presenting a review of etiopathogenic hypotheses concerning these comorbidities.