Abstract
BACKGROUND: Hepatitis C virus (HCV) infection is commonly comorbid with opioid dependence (OD). We wanted to compare the neurocognitive functions of OD subjects with or without HCV [HCV (+), HCV (-)] and healthy controls (HC). METHODS: We recruited 40 adult subjects (age 18-55 years) in each group. HCV(+) group had a detectable viral load. Subjects with HIV or hepatitis B infection, head injury, epilepsy, or comorbid mental illness were excluded. We administered Standard Progressive Matrices (SPM), Wisconsin Card Sorting Test, Iowa Gambling Task (IGT), trail-making tests A and B, and verbal and visual N-back tests (NBT) one week after opioid abstinence. The group differences in cognitive performance were adjusted for age and years of education. Effect size (ES) is expressed as Cohen's D. RESULTS: The HCV(+) and HCV(-) groups did not differ in potential effect modifiers (age and years of education) or confounders (age of opioid initiation, duration of use, dependence severity, tobacco use, and cannabis use) of neuropsychological functioning. HCV(+) showed significantly poorer performance than HCV(-) in SPM (P = 0.006; ES = 0.72). Both HCV(+) and HCV(-) performed worse than controls in IGT(P < 0.001; ES = 0.8) and visual NBT[P < 0.01 and ES > 1 for total errors]; HCV(+) had a larger ES of group difference than HCV(-). HCV(+) had higher error scores in verbal NBT than control. CONCLUSION: HCV(+) has poorer general intellectual ability and reasoning than HCV(-) persons and controls. Chronic HCV infection causes a higher magnitude of dysfunction in decision-making and visual working memory in opioid-dependent individuals.