HIV directly affects the CNS, primarily causing subcortical neuropathology. Dementia as the initial presentation is rare, but organic mental changes that mimic many functional disorders can occur during the course of infection. The mental status examination is not adequately sensitive to detect noncognitive dysfunction, and subjective complaints, neurological signs, reduced T4 lymphocytes, CSF abnormalities, diffuse slowing on ECG, mild cerebral atrophy on brain CT, and nonspecific hyperdensities on brain magnetic resonance imaging do not correlate reliably with early and subtle HIV-induced neuropsychological impairment. Zidovudine (AZT) can delay or reverse mental deficits, and psychostimulants can reduce apathetic withdrawal, but high-potency neuroleptics can cause neuroleptic malignant syndrome.