Current Topic Review: The Role of Comorbid Substance Abuse in Suicide Risk for Bipolar Patients

Nancy Russ

Disclosures

May 20, 2003

In This Article

What Is Bipolar Disorder?

Bipolar disorder is a long-term recurrent illness,[1] often referred to as manic depression. It is characterized by extreme fluctuations in mood, ranging from euphoria to severe depression, interspersed with periods of normal mood (ie, euthymia). Bipolar disorder affects approximately 1% to 2% of the population and often starts in early adulthood.[2] It is associated with a substantial burden of morbidity and mortality.[3,4,5,6]

Two large epidemiologic studies of psychiatric disorders -- the National Institute of Mental Health Epidemiologic Catchment Area (ECA) study[7] and the National Comorbidity Survey (NCS)[8] -- reported an association between alcoholism and mood disorders. The ECA study revealed that 60.7% of people with bipolar I disorder had a lifetime diagnosis of a substance use disorder (SUD); 46.2% had an alcohol use disorder; and 40.7% had a drug abuse or dependence diagnosis. (The numbers add up to more than 100% due to overlap.)

Using data from the ECA study, Helzer and Przybeck[9] found that mania (bipolar I disorder) and alcohol use disorders are 6.2 times more likely to occur than would be expected by chance, and they co-occur more often than do alcoholism and unipolar depression.

Although researchers have proposed explanations for the strong association between alcoholism and bipolar disorder, the exact relationship is not well understood.[2] One proposed explanation is that certain psychiatric disorders, including bipolar disorder, may be risk factors for substance abuse. Symptoms of bipolar disorder may emerge during the course of chronic alcohol intoxication or withdrawal.[10]

Other studies suggest that alcoholism is often a complication of bipolar disorder rather than a risk factor for it.[11] Feinman and Dunner[12] conducted a study of 3 groups of patients: a primary group with bipolar disorder and no history of substance abuse, a group with bipolar disorder complicated by substance abuse that began after the onset of bipolar disorder, and a secondary group with bipolar disorder that was preceded by substance abuse. The researchers found that the group with bipolar disorder complicated by substance abuse had a significantly earlier age of onset of bipolar disorder than the other groups.

Another theory, supported in a study by Tohen and associates,[13] is that alcohol use and withdrawal may affect the same brain chemicals that are involved in bipolar illness, thereby allowing one disorder to change the clinical course of the other.

There is considerable evidence to support the possibility of familial transmission of both bipolar disorder and alcoholism.[14,15] Common genetic factors may play a role in the development of this comorbidity, but the relationship is complex.[13] In a family study of alcoholism and mood disorders, Preisig and colleagues[11] studied 226 people with alcoholism (some with and some without a mood disorder) and their family members. The researchers found a greater familial association between alcoholism and bipolar disorder (odds ratio [OR] = 14.5) than between alcoholism and unipolar depression (OR = 1.7).

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