Investigating neurocognitive features of hepatitis C virus infection in drug users: potential challenges and lessons learned from the HIV literature.

Studies of neurocognition in drug users with hepatitis C virus (HCV) infection are urgently needed but face many challenges. We review similarities between human immunodeficiency virus (HIV) and HCV infection in their neurocognitive features, discuss challenges associated with research among drug users, advocate that the HIV literature can usefully inform studies of HCV, and review findings by our group on neurocognition among substance users with HIV and/or HCV infection.