HIV-Related Neurocognitive Disorders and Drugs of Abuse: Mired in Confound, Surrounded by Risk

It has long been known that human immunodeficiency virus (HIV) uses the central nervous system (CNS) as a reservoir and nursery to replicate; therein, it does damage to cells and creates an inflammation that in turn allows for more virus to pass the blood–brain barrier. The inflammatory process itself can cause considerable damage. Neurocognitive disturbance from HIV infection is also known to occur at any stage of the infection. Likewise, common drugs of abuse also have adverse neurocognitive effects on their own. This review examines the literature available to try to elucidate the mechanisms of neurocognitive disorders in the HIV-infected individuals who have used drugs of abuse. Although the incidence of HIV-associated dementia (HAD) has decreased with the advent of highly active anti-retroviral therapy, less severe forms of neurocognitive impairment persist, even with supported immune systems and undetectable viral loads. Considerations for prevention are discussed.