COMMENTARY

Substance Abuse and Bipolar Disorder

Marcia L. Verduin, MD; Bryan K. Tolliver, MD, PhD; Kathleen T. Brady, MD, PhD

Disclosures

December 05, 2005

In This Article

Bipolar Disorder and Substance Abuse

There is a growing body of literature exploring the interface between bipolar disorder and substance use disorders (SUDs). Symptoms of mood instability are among the most common psychiatric symptoms seen in addicted individuals. Exploration of the co-occurrence of bipolar disorder and SUDs is clinically important because of the negative impact on course, treatment outcome, and prognosis of both disorders. In this article, the prevalence and relationship of co-occurring mood disorders and SUDs are explored, and evidence-based psychotherapeutic and pharmacotherapeutic treatments are reviewed.

The co-occurrence of bipolar disorders and SUDs is well-documented. Three large epidemiologic studies have established the prevalence of this comorbidity: the Epidemiological Catchment Area study (ECA), the National Comorbidity Study (NCS), and the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).[1,2,3] Results from the ECA and NCS studies indicated that bipolar disorder is the Axis I condition most associated with an SUD. Further, according to data from the ECA, nearly 60% of individuals with bipolar disorder have a co-occurring SUD. The more recent NESARC study found that of all mood and anxiety disorders, mania is most strongly associated with SUDs. In treatment-seeking samples, NESARC data suggest that approximately 41% of individuals with an alcohol use disorder and 60% of individuals with a drug use disorder have a co-occurring mood disorder. Among individuals seeking treatment for a mood disorder, approximately 20% have a comorbid SUD.[3] Clearly, comorbid SUDs affect a significant subpopulation of individuals with bipolar disorder, highlighting the need for evidence-based treatment recommendations for this population.

While bipolar disorder and SUDs are strongly associated, the exact relationship between the 2 is complex. Several theories have been proposed to explain the high co-occurrence. The self-medication model posits that individuals with bipolar disorder use substances of abuse to counteract unpleasant affective symptoms. Although patients often claim that they use alcohol or drugs because of mood problems, most evidence indicates that substance use worsens mood symptoms, and there is little evidence to support the self-medication hypothesis. Another explanation for the high occurrence of SUDs in bipolar patients is that some of the characteristics of bipolar disorder, such as impulsivity, poor judgment, and excessive involvement in pleasurable activities, predispose to the development of SUDs. There is also a compelling body of evidence that substance use is associated with the development of bipolar disorder for some individuals.[4] It is possible that substance abuse can "unmask" an affective disorder in genetically vulnerable individuals due to shared pathophysiology in neurotransmitter systems or adaptations in signaling pathways common to both disorders.[5] The evidence supporting a genetic link between bipolar disorder and SUDs remains inconclusive. It is hoped that the increasing number of genetic studies focused on psychiatric illness will shed some light on this important area. In summary, it remains unclear whether any, all, or some combination of the models discussed explain the high comorbidity between bipolar disorder and SUDs. The relationship is complex and bidirectional, suggesting an ongoing interaction between disorders that may best be explained by a combination of mechanisms.

Multiple studies have demonstrated a negative impact of substance abuse on clinical outcomes in patients with bipolar disorder.[6] Severity of psychiatric disorders in general, and bipolar disorder in particular, is strongly related to comorbidity.[7] The percentage of alcoholic bipolar patients who attempt suicide is almost twice that of nonalcoholic bipolar patients.[8,9] Substance abuse is associated with more mixed depressive-manic episodes,[10] increased frequency of mood swings, and more hospitalizations in bipolar patients currently abusing substances than in bipolar patients without SUDs.[11] Longitudinal studies have demonstrated that comorbid substance abuse is associated with shorter time to relapse to mania[12] and longer time to recovery from a mood episode.[13] More recently, a multicenter study found that bipolar patients with comorbid SUDs have lower recovery status, poorer role functioning, and lower quality of life than bipolar patients without SUDs, whether their substance abuse is current or past.[14]

Of note, the course of bipolar disorder in patients with comorbid alcohol use disorders has been shown to differ depending on whether the bipolar disorder or alcohol use disorder was antecedent.[15,16] Patients whose alcoholism preceded the onset of bipolar disorder have been shown to be older at the onset of their bipolar illness, recover more quickly from affective episodes, and suffer fewer affective episodes than patients with antecedent bipolar disorder.[15,16] In the latter study, patients with antecedent onset of bipolar disorder were more likely to exhibit symptoms of an alcohol use disorder at follow-up than those patients whose alcohol use disorder preceded their bipolar presentation. Notably, the onset of new alcohol abuse or dependence in bipolar patients during the course of this study typically occurred within 1 year of the first hospitalization for mania, suggesting an opportunity for prevention of comorbid SUDs in bipolar patients.[15]

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