Impact of Hepatitis C Virus Therapy on Central Nervous System Outcomes

About 40 HCV+ and HCV/HIV co-infected patients with neurocognitive impairment (NCI) and a history of substance abuse will take part in this study. INCLUSION CRITERIA 1. Adults (18 years old or older) with chronic HCV and NCI with a GDS greater than or equal to 0.35 (n=40). 2. Presence of chronic HCV infection based on chart review will be defined as positive for anti-HCV antibody or HCV RNA at least 6 months before screening. 3. Plan to receive HCV treatment from their primary care physician within 1 month of enrollment. 4. For the HIV/HCV co-infected group only, subjects must have HIV. HIV status will be obtained through self-report. Self-report will be confirmed at the pretreatment visit using a HIV-1 point of care test. In the event that point of care test and self-report are discordant, then HIV status will be confirmed by a licensed Western blot or a second antibody test by a method other than the initial rapid HIV-1 and/or E/CIA, or by HIV-1 antigen, or plasma HIV-1 RNA viral load. EXCLUSION CRITERIA 1. Cirrhosis or bridging fibrosis (mHAI stages 4-6 or its equivalent). * Liver biopsy at any time showing mHAI stage 4 or higher fibrosis OR * FibroScan within 12 months demonstrating liver stiffness of ≥9.5 kPa OR * APRI ≥2.0 and FIB-4 ≥3.25 * NOTE: If APRI and FIB-4 are discordant one of the other forms of fibrosis staging must be used. 2. Any cause of liver disease other than chronic HCV infection, including but not limited to the following: * Hemochromatosis * Alpha-1 antitrypsin deficiency * Wilson's disease * Autoimmune hepatitis * Alcoholic liver disease * Drug-related liver disease 3. Severe NC confounding conditions (stroke, head injury, or developmental learning disability). 4. Regular use of anti-inflammatory drugs. 5. Current or recent treatment with pegylated interferon (PEG-IFN). 6. Other active inflammatory process (major infection, malignancy, rheumatoid arthritis/autoimmune disorder) within the prior 28 days. 7. Uncontrolled or active depression or other psychiatric disorder that in the opinion of the site investigator might preclude adherence to study requirements or impact NC functioning and assessments. 8. Active drug or alcohol use or dependence that, in the opinion of the site investigator, would interfere with adherence to study requirements. 9. Presence of active or acute AIDS-defining opportunistic infections within 12 weeks prior to study entry.