Comorbidity of substance use with depression and other mental disorders: from Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) to DSM-V.

Aims: To arrive at recommendations for addressing co-occurring psychiatric and substance use disorders in the development of the Diagnostic and Statistical Manual of Mental Disorders fifth edition (DSM-V) criteria.

Methods: Synthesis of findings of other papers from a consensus conference and from the literature on diagnosis and treatment of co-occurring psychiatric and substance use disorders. Most of the relevant studies examine co-occurring depression.

Results: The diagnosis and treatment of psychiatric syndromes that co-occur with substance use disorders has been a source of controversy, fueled in part by limitations of pre-DSM-IV nosologies. The DSM-IV scheme of classifying co-occurring disorders as primary (also referred to as independent) or substance-induced has promise in terms of good predictive validity, although pertinent longitudinal and treatment studies are limited. The substance-induced category answers the need of clinicians for a way to categorize patients with clinically significant psychiatric symptoms that occur in the setting of ongoing substance use.

Conclusions: DSM-V should retain the primary (independent) and substance-induced categories. In DSM-IV these categories are broadly defined and leave much to clinical judgement. Existing data sets should be brought to bear to refine the criteria, making them more detailed with clearer anchor points and more specificity around particular substances and psychiatric syndromes. More longitudinal studies and clinical trials are also needed. Looking beyond DSM-V, co-occurring psychiatric syndromes are likely to be important in the quest for a nosology founded on pathophysiology.