HIV-1-associated dementia: a basic science and clinical perspective.

HIV-1 associated dementia (HAD) is a metabolic encephalopathy induced by viral infection and fueled by immune activation of brain mononuclear phagocytes (perivascular and parenchymal macrophages and microglia). These same cells serve as reservoirs for persistent infection and sources for soluble neurotoxins. Neurologic impairments are manifested by cognitive, behavioral, and motor abnormalities that occur years after viral exposure and are associated with depletion of CD4+ T lymphocytes and high viral loads. Improvements in antiretroviral and adjunctive therapies have decreased HAD incidence, but cognitive dysfunction remains a cause of morbidity in many infected persons.