INTRODUCTION

Human immunodeficiency virus (HIV)–infected patients are vulnerable to developing altered mental status (AMS) for myriad reasons including the effects of HIV itself, the accompanying immune dysfunction, associated systemic illness, comorbid psychiatric disorders, and complicated medication regimens. Highly active antiretroviral therapy (HAART) has decreased the incidence of central nervous system (CNS) opportunistic infections (OIs) and HIV-associated dementia, but the benefits are not absolute. Moreover, patients with undiagnosed or untreated HIV infection may present with AMS. In addition to CNS OIs and complications of complex multisystem disease, immune reconstitution events developing in the early weeks and months after initiating HAART may affect the brain and cause AMS.

EPIDEMIOLOGY

Before HAART became the standard of HIV care in the developed world, approximately half of HIV-infected patients developed symptomatic central or peripheral nervous system disease, with neuropathology observed in nearly all individuals dying with HIV/acquired immunodeficiency syndrome (AIDS). Since the advent of HAART, the incidence of dementia, the major cerebral OIs (cryptococcal meningitis, toxoplasmosis, progressive multifocal leukoencephalopathy [PML]), and primary CNS lymphoma (PCNSL) has fallen. HIV-associated dementia is also less common and more indolent in patients on HAART. In the United States, fewer patients now develop the mutism, quadriparesis, and incontinence that were common with late-stage infection in the early years of the AIDS epidemic.