Identifying the cause of the depression in individuals with alcohol(Drug information on alcohol) dependence has been thought to be important for determining the course of the disorder and the optimal treatment approach. For example, if the depressive symptoms are clearly related to alcohol use, then an antidepressant may not have any therapeutic impact beyond what abstinence would achieve. In some cases, depressive symptoms will spontaneously remit with abstinence from alcohol. In such cases, antidepressant pharmacotherapy may be an unnecessary cost and may be burdensome to the patient. However, it is often difficult to distinguish a substance-induced depression from major depression in the presence of alcohol dependence because the clinical symptoms of a substance-induced depression can appear identical to those seen in major depression.
Prolonged abstinence from alcohol can be of great value in making a distinction. Indeed, Brown and Schuckit11 demonstrated a significant drop in depressive symptoms for those with primary alcohol dependence who completed a 4-week inpatient program. Nonetheless, many patients have difficulty in abstaining from alcohol during outpatient treatment and eventually may drop out of treatment because of continued drinking and/or deepening depression. To this point, Greenfield and colleagues12 demonstrated that untreated depression—whether primary or secondary—predicted worse drinking outcomes. Finally, while depression may precede or be precipitated by alcohol dependence, implying causation, there may be common risk factors for depression and for alcohol dependence. These include stressful events, psychological trauma, and genetic vulnerability that lead to co-occurring expression, without one disorder causing the other.
DSM-IV-TR distinguishes between major and substance-induced depressive episodes and related disorders. For a depressive episode to be considered substance-induced, the depressed mood and/or diminished interest and pleasure must occur during (or within 1 month of) periods of intoxication or withdrawal and symptoms cannot be better explained by an independent mood disorder. A careful history can help make the differential diagnosis.
The following scenarios strongly suggest an independent mood disorder (eg, major depression):
• The mood disturbance precedes alcohol use
• The mood disturbance persists following prolonged abstinence (at least 1 month)
• Depressive symptoms occur in excess of those typically seen considering the quantity and frequency of alcohol consumption
Several large studies that carefully assessed DSM-IV criteria have shown that the prevalence of primary, independent depressive disorders (eg, major depression) are more common than substance-induced disorders in individuals with alcohol use disorders.10,13 Furthermore, women who are alcohol-dependent and depressed are more likely to have an independent mood disorder than a substance-induced disorder.13
Today in the United States, alcohol dependence is almost always treated in an outpatient setting, where continued drinking and poor treatment attendance can be major obstacles to observing periods of abstinence. Clinicians are typically expected to decide how to treat depression in patients who are actively drinking, without benefit of observing that patient during an extended period of abstinence. Interview techniques that have been developed to help clinicians determine the origin of a patient’s depression have demonstrated reliability and validity in academic settings.14-16 However, little is known of the utility of these techniques in general practice.
Further studies are needed to elucidate a way to make accurate diagnoses of major depressive disorder and substance-induced depression in the presence of current alcohol dependence. It would be beneficial to know precisely under what conditions antidepressant therapy would yield optimal outcomes for treating comorbid depression and alcohol dependence.