Comorbidity of Substance Use and Axis I Psychiatric Disorders

Kathleen T. Brady, MD, PhD


Medscape Psychiatry & Mental Health eJournal. 1998;3(4) 

In This Article


A number of studies have demonstrated that up to 50% of treatment-seeking schizophrenic patients are alcohol or illicit drug dependent and more than 70% are nicotine dependent.[6,7,8,9] Epidemiologic studies indicate that individuals with schizophrenia, when compared with the general population, have substantial risk (odds ratio, 4.6) for having a co-occurring substance use disorder.[1]

As with other psychiatric symptoms, assessing psychotic symptoms in the face of active substance use can be difficult. A recent review[10] examines important factors in differentiating schizophrenia from drug-induced psychotic symptoms, including the nature of the psychotic material. Again, the most helpful factors in making this differential diagnosis are careful history concerning symptoms during abstinent periods and observation of symptoms during monitored abstinence.

Substance abuse often goes undetected in patients with schizophrenia. Substance-using patients have poorer long-term outcomes, as compared with nonusing schizophrenic patients,[11] which makes it critical to uncover and aggressively treat substance use problems in this patient population. Routine urine testing in triage settings and during periods of poor clinical response is essential.[8]

The optimal management of patients with comorbid substance use and schizophrenia involves both pharmacotherapy and psychotherapy (Table I). While there is little empirical data concerning specific pharmacotherapeutic strategies, recent clinical data suggest that atypical neuroleptic agents, such as clozapine, may be particularly useful in this population.[12,13] Because of the serotonergic action of clozapine, this finding may be of particular interest. The serotonergic system has been implicated in the control of alcohol consumption.[14] Antipsychotic agents with serotonergic activity may have the added benefit of decreasing alcohol consumption while exerting their antipsychotic effect. These agents are also associated with a smaller incidence of movement disorder than typical neuroleptics.

Another important consideration in the pharmacotherapy of schizophrenic substance users is the use of antidepressant therapy. Management of dysphoric affect in substance abusing patients may be an important step in successful treatment. Siris and coworkers[15] have preliminary evidence that adjunctive antidepressant medication added to neuroleptic medication may be useful for some stable, dysphoric, substance-abusing, schizophrenic patients. A group of investigators studying adjunctive desipramine treatment in a small group of cocaine-abusing schizophrenics found that the desipramine-treated group had better rates of retention in treatment and fewer cocaine-positive urine tests.[16]

The psychotherapeutic management of the schizophrenic substance abuser is critical. Close monitoring via urinalysis and breathalyzer along with clear limit setting are also critical. Feedback should be given in an empathic and nonjudgmental manner. The confrontational group-process approach often used for substance abusers has little value in the treatment of the schizophrenic substance abuser[17] and may exacerbate psychosis. Ziedonis and Trudeau[18] have noted poor motivation to quit substances in many schizophrenic patients and suggest a dual-diagnosis treatment-matching strategy based on motivation levels, substance of abuse, and illness severity.

In conclusion, substance use disorders are often a problem for individuals with schizophrenia. Optimal management includes psychotherapeutic as well as pharmacotherapeutic intervention. While there is still much work to be done, recent studies are encouraging, with preliminary positive outcomes from combined approaches drawn from the psychiatric and substance abuse fields.


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