Hepatitis C, interferon alfa, and depression

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Abstract
Hepatitis C virus (HCV) infection is the most common cause of chronic liver disease in the United States. An estimated 1.8% of the U.S. population carries the antibody to HCV, with 74% chronically infected.1,2 Of these, 25% to 35% progress to cirrhosis with an estimated 8,000 to 10,000 deaths every year. In addition to its medical challenge, HCV also presents a psychiatric challenge. Patients with HCV are more likely to have psychiatric disorders, with depression being the most frequent and clinically important. Presently, interferon (IFN)-based therapies (with or with- out ribavirin) are the standard treatment for chronic HCV. Although their mechanisms of action are not completely understood, preventing de novo infection of susceptible cells may be the most important.3 The actions that confer benefit may also be responsible for the side effects of IFNs, which are dose dependent and occur with any of the available prepara- tions. Although most are minor, neuropsychiatric side effects can be serious, requiring dose reduction or discontinuation. HEPATITIS C AND DEPRESSION Two separate lines of evidence support an association between HCV and depression. First, patients with psychiatric disorders have a higher prevalence of HCV infection. Second, patients with chronic hepatitis C may have a higher preva- lence of psychiatric disorders including depression. The prevalence of HCV is greater in patients with psychiatric disorders than in the general population. In intravenous drug users, 74% to 100% of individuals are infected with HCV.4-7 Although not everyone using drugs qualifies for a psychiatric diagnosis (for example, one-time or occasional users), the majority of chronic users meet the criteria for substance abuse or substance dependence disorder (DSM-IV Diagnostic criteria). In patients abusing alcohol, the prevalence of HCV-positive serology ranges from 6.7% to 18.4%. Interest- ingly, in individuals with a history of alcohol abuse and underlying liver disease, HCV antibodies are twice as com- mon as in those without liver disease.8 In one large retrospec- tive study, 6.7% of patients hospitalized for mental retarda- tion, psychosis, or dementia were infected with HCV. Among these diagnoses, psychosis was the most important indepen-