Despite effective viral control by Antiretroviral therapy (ART), HIV associated neurocognitive disorder (HAND) persists in 30-50% of patients. In the ART era, neuropathology has shifted from a rapidly progressing encephalitic condition to a prolonged neurodegenerative disease with pathologic features including astrogliosis, microgliosis, dendritic damage, and especially white matter deficits. White matter alterations include decreased myelin sheath thickness, myelin lesions, and abnormal myelin protein expression. The severity of white matter damage correlates with the amount of time on ART therapy. Transcriptome analysis of HIV patients on ART revealed decreases in genes associated with oligodendrocyte maturation and myelination. Using a well-characterized oligodendrocyte culture model, we have recently reported that representative drugs from the protease inhibitor class of ART (ritonavir and lopinavir) inhibit differentiation of oligodendrocyte precursors to mature oligodendrocytes in a dose-dependent manner, independent of cell death. Intravenous administration of ritonavir to mice for only two weeks significantly decreased the expression of several myelin proteins. Further, myelin basic protein (MBP) was significantly decreased in the cortex of HIV patients who were on ART and exhibited HAND. These findings are the first to demonstrate on an experimental level that ART can disrupt myelin development and maintenance. We hypothesize that ART compounds alter oligodendrocyte differentiation, function, and survival, contributing to the persistence of HAND in the post-ART era. Our new preliminary data suggest that a subset of drugs from the nucleoside reverse transcriptase inhibitor (NRTI) class and from the integrase inhibitor class also decrease oligodendrocyte differentiation in vitro. In this proposal, we will use our oligodendrocyte cell culture system to identify mechanisms by which ART drugs decrease oligodendrocyte maturation, including lipid regulation and cellular stress pathways in oligodendrocytes, which regulate myelin membrane generation. The second aim of this proposal will examine whether ART drugs can impede remyelination after a demyelinating insult using small animal model of HIV-induced neuroinflammation and the cuprizone model of demyelination. The third aim will compare white matter changes in our rodent model with human patients using image analysis. Results from these aims should help devise more rational drug therapies without myelin deficits to reduce HAND.