Drug abuse and bipolar disorder: comorbidity or misdiagnosis?

Bipolar disorder is a common, severe and cyclic psychiatric illness. A strong association between alcohol dependence and bipolar disorder has been reported in numerous studies. The abuse of other drugs including cocaine, amphetamines, opiates, cannabis, and prescription medications in bipolar patients is also an important public health concern and has been less extensively investigated. This review examines the abuse of drugs other than alcohol or nicotine in people with bipolar disorder. The high rates of milder affective symptoms but not mania observed in patients in drug abuse treatment settings suggests the symptoms may in many cases be associated with the drug use. However, such patients presenting in psychiatric settings might be suffering from cyclothymic and related attenuated bipolar disorders (type II). Substance abuse may be associated with medication non-compliance, more mixed or dysphoric mania and possibly an earlier onset of affective symptoms and more hospitalizations. The pharmacotherapy of patients with bipolar disorder and drug abuse is examined, including evidence on the use of mood stabilizers, neuroleptics and the newer atypical antipsychotics in this population.