HIV-associated neurocognitive disorder (HAND) is an umbrella term used to describe neurodegenerative disease caused by human immunodeficiency virus (HIV)-1 infection and may affect more than 30% of people with HIV regardless of virological suppression. The central nervous system acts as a reservoir for HIV with neuronal damage occurring both at the time of initial HIV infection and throughout the chronic phase. Although there is a decreasing incidence of HIV-associated dementia, milder forms of cognitive impairment have increased, regardless of HIV virological suppression and immune recovery. Cognitive impairment is the most common central nervous system complication in people with HIV.
There are three categories of HAND, each associated with an increasing level of impairment:
- Asymptomatic neurocognitive impairment (ANI) shows HIV-associated impairment in cognitive function, but everyday functioning is not affected.
- Mild neurocognitive disorder (MND) is characterised by HIV-associated impairment in cognitive function where interference in everyday functioning is displayed. 
- HIV-associated dementia (HAD) shows marked impairment in cognitive function, especially in learning of new information, information processing, and attention or concentration.