Similarly, inpatients with premorbid or substanceinduced depression were more likely to meet the criteria for drug dependence during outpatient follow-up. 10 In addition, patients who developed depression during the first 26 weeks after hospitalization were 3 times more likely than those without depression to relapse into drug dependence during follow-up.
Alcohol dependence may hasten the progression of depression. A study on the prognostic effect of alcoholism on the 10-year course of depression found a deleterious influence of current alcoholism after recovery from depression. 11 Patients with MDD were more likely to transition from being ill to improving if either they were forgoing alcohol or had never abused it. Another investigation verified that alcohol and drug dependence increased perceptions of affective symptomatology. 12
Substance-induced depression also increases the risk for suicide. In 602 patients with substance dependence, depression was classified as occurring before dependence, during abstinence, or during substance use. 13 Depression increased the risk for suicide in 34% of patients
who had already attempted suicide at least once. Compared with depression absent substance abuse, depression preceding substance use was associated with high vulnerability to additional psychopathology, depressive episodes that were more severe and greater in number, and more suicide attempts. Substance dependence predicted severity of suicidal intent, and abstinence predicted number of attempts.
Psychiatric hospitalizations often involve patients with a history of suicidal thinking or behavior and substance-induced depression. Clinicians can make reliable assessments of the degree to which a presenting psychiatric syndrome is substance-induced. 14 These patients require addiction treatment, including outpatient addiction services capable of caring for suicidal persons. These individuals also are more likely to be homeless, unemployed, and uncooperative. 15
Taking a psychiatric history and making a detailed inquiry into potential suicidal behavior, recent substance abuse, and current mood symptoms are warranted in persons with depression and/or SUD. Close follow-up is especially important for depressed patients likely to relapse into alcoholism soon after hospital discharge. Failure to recognize MDD or a bipolar disorder in such a patient may result in more relapses, recurrence of mood episodes, and elevated risk of completing suicide. 16
Bipolar Clinical Considerations
There is a lack of clarity regarding the effect of moderate-to-excessive alcohol use on the course of bipolar disorders. There is a negative effect on patients with alcohol-induced bipolar depression. In a study of group therapy patients with bipolar disorder co-occurring with substance dependence, data indicated that number of days of alcohol use predicted development of depression a month later. 17 These findings were associated with heavy alcohol consumption. In these patients, substantial drinking increased the risk of a depressive episode. In another study, comorbid SUDs were correlated with suboptimal treatment compliance. 18 The authors of a 1998 literature review concluded that comorbid SUD makes bipolar symptoms more severe. 19
A number of studies have failed to confirm a negative effect of alcohol on bipolar depression. 20 There were no differences in 1-year course and outcome between bipolar patients with different alcohol use levels (abstinence, incidental use, moderate abuse, excessive consumption). Other investigators concluded that SUDs were not associated with slower recovery from depression but could contribute to a higher risk of switching to a manic, mixed, or hypomanic state. 21