The systemic administration of interferon-alpha (IFN-A) is associated with frequent and well characterized neuropsychiatric toxicity. The primary purpose of this study is to determine if treatment with IFN-A in combination with ribavirin alters human brain biochemistry as measured by proton magnetic resonance spectroscopy. The study population will be drawn from subjects simultaneously enrolled in a NIDDK protocol (98-DK-0003) that employs IFN-A and ribavirin for the treatment of hepatitis C virus (HCV) infection. Subjects will be evaluated prior to IFN-A/ribavirin treatment and then followed prospectively with the specific aim of identifying the emergence of central nervous system (CNS) effects. The principal outcome measures will be as follows: determinations of specific brain metabolites as measured by proton magnetic resonance spectroscopy (1H-MRS), a brief, non-invasive, and minimal risk procedure; ratings of mood, cognitive, and behavioral symptoms.

The hypotheses being tested in this study are as follows:

1. Treatment with IFN-A/ribavirin will decrease measures of neuronal integrity (NAA/CRE ratio) in a brain region specific fashion.
2. The degree of change in NAA/CRE in certain brain regions (e.g. prefrontal cortex) will correspond to the development of mood or cognitive symptoms.

The questions being asked in this study are relevant to the clinical management of HCV patients, since adverse neuropsychiatric effects of IFN-A and ribavirin frequently complicate protocol participation and occasionally result in a subject being taken off protocol. There are no anticipated number of patient days per year required for this study, as all participants will be simultaneously enrolled in NIDDK protocol 98-DK-0003.