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

Abstract & Introduction

Data from a number of sources indicate substance use disorders and some psychiatric disorders commonly co-occur. Data from a recent epidemiologic survey indicate that 78% of alcohol-dependent men and 86% of alcohol-dependent women meet lifetime criteria for at least 1 other psychiatric disorder. More than 50% of schizophrenic patients have a substance use disorder. The relative risk for co-occurrence of substance use disorders with any affective disorder has an odds ratio of 2.3, with an odds ratio of 2.7 for major depression and an odds ratio of 9.2 for bipolar disorder. Approximately 36% of individuals with an anxiety disorder have a substance use disorder. This article presents an overview of diagnostic issues, and pharmacotherapeutic and psychotherapeutic treatment options for patients with co-occurring substance abuse and psychiatric diagnosis. The most successful approaches appear to be those that combine cutting-edge knowledge from the substance abuse and psychiatric fields.

The co-occurrence of substance use and other psychiatric disorders has become an area of active investigation in recent years. Two epidemiologic surveys have examined the prevalence of psychiatric and substance use disorders in community samples: the National Institute of Mental Health Epidemiologic Catchment Area (ECA) study[1] conducted in the early 1980s, and the National Comorbidity Study (NCS) conducted in 1991.[2] Data from the ECA study estimates that 45% of individuals with an alcohol use disorder and 72% of individuals with a drug use disorder had at least 1 co-occurring psychiatric disorder.[2] In the NCS, approximately 78% of alcohol-dependent men and 86% of alcohol-dependent women met lifetime criteria for another psychiatric disorder, including drug dependence.[3]

Differential diagnosis can often be difficult because symptoms of psychiatric disorder are mimicked by substance use. Accurate diagnosis and differentiation between substance-induced states and independent psychiatric disorders can be a challenge. A full discussion of problematic issues in the diagnosis of comorbid substance use disorders and psychiatric disorders is beyond the scope of this paper. However, it is clear that the best way to differentiate substance-induced transient psychiatric symptoms from psychiatric disorders that warrant independent treatment is through observation of symptoms during a period of abstinence. Transient substance-related states will improve with time. It is likely that the minimum amount of time necessary for diagnosis will vary according to the comorbid condition being considered. For depression and many anxiety disorders, there appears to be symptom resolution for 2 to 4 weeks after last use.[4,5] There is a risk of overdiagnosis of psychiatric disorders if diagnosis is made earlier. Other psychiatric disorders are not as well studied in this regard. It is likely, however, that a diagnosis of schizophrenia, mania, or an eating disorder could be made with shorter periods of abstinence because symptoms of these disorders have less overlap and are more easily distinguished from substance-induced and withdrawal states.

A second challenge is optimal treatment planning. When medication treatment is indicated, particular attention must be paid to potential toxic interactions of psychotherapeutic agents with drugs and alcohol, as well as to the abuse potential of the agents being used. Unfortunately, there is little information available concerning the use of pharmacotherapeutic agents in a dual diagnosis population. Most pharmacologic treatment studies categorically exclude individuals with substance use disorders, and studies of agents used to treat substance use disorders, such as naltrexone, have excluded patients with a psychiatric diagnosis.

Psychosocial modalities of treatment are powerful interventions for psychiatric and substance use disorders. Detailed discussion of appropriate psychosocial intervention for each condition is beyond the scope of this review, but a general point concerning the treatment of co-occurring disorders is that both disorders should be addressed concurrently, with varying emphasis based on clinical judgment and patient response. Specific psychotherapies for psychiatric disorders can be used effectively in parallel with other addiction treatment modalities (eg, 12-step therapies, relapse prevention strategies) and pharmacotherapy.

Some clinically relevant substance use and psychiatric co-morbidities will be reviewed, and, for each category of psychiatric diagnosis discussed, prevalence rates, differential diagnosis, and available information on treatment will be briefly discussed.


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