HIV-associated neurocognitive disorder.

Human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND) affects roughly half the HIV-positive population. The symptoms of cognitive slowing, poor concentration, and memory problems can impact on everyday life. Its diagnosis is validated where possible by identifying deficits in two cognitive domains on neuropsychologic testing in patients either with or without symptoms. Corroborating evidence may be found on imaging, blood tests, and cerebrospinal fluid analysis, though sensitive and specific biomarkers are currently lacking. The introduction of combined antiretroviral therapy in the 1990s has generated a therapeutic paradox whereby the number of severe cases of HAND has fallen, yet milder forms continue to rise in prevalence. New emphasis has been placed on identifying the cause of apparent ongoing HIV infection and inflammation of the central nervous system (CNS) in the face of durable systemic viral suppression, and how this equates to the neuronal dysfunction underlying HAND. The interaction with aging and comorbidities is becoming increasingly common as the HIV-positive population enters older adulthood, with neurodegenerative, metabolic, and vascular causes of cognitive impairment combining and probably accelerating in the context of chronic HIV infection. Therapies targeted to the CNS, but without neurotoxic side-effects, are being investigated to attempt to reduce the likelihood of developing, and improving, HAND.