AIDS Dementia Complex

AIDS dementia complex (ADC; also known as HIV dementia, HIV encephalopathy, HIV-associated dementia and HIV-associated neurocognitive disorder) is a common neurological disorder associated with HIV infection and AIDS. It is a metabolic encephalopathy induced by HIV infection and fueled by immune activation of macrophages and microglia. These cells are actively infected with HIV and secrete neurotoxins of both host and viral origin. The essential features of ADC are disabling cognitive impairment accompanied by motor dysfunction, speech problems and behavioral change. Cognitive impairment is characterised by mental slowness, trouble with memory and poor concentration. Motor symptoms include a loss of fine motor control leading to clumsiness, poor balance and tremors. Behavioral changes may include apathy, lethargy and diminished emotional responses and spontaneity. Histopathologically, it is identified by the infiltration of monocytes and macrophages into the central nervous system (CNS), gliosis, pallor of myelin sheaths, abnormalities of dendritic processes and neuronal loss.

ADC typically occurs after years of HIV infection and is associated with low CD4+ T cell levels and high plasma viral loads. It is sometimes seen as the first sign of the onset of AIDS. Prevalence is between 10-24% in Western countries and has only been seen in 1-2% of India based infections. With the advent of highly active antiretroviral therapy (HAART), the incidence of ADC has declined in developed countries, however its prevalence is increasing. HAART may prevent or delay the onset of ADC in people with HIV infection, and may also improve mental function in people who already have ADC.

Dementia only exists when neurocognitive impairment in the patient is severe enough to interfere markedly with day-to-day function. That is, the patient is typically unable to work and may not be able to take care of him or herself. Before this, the patient is said to have a mild neurocognitive disorder.