ABSTRACT
Three phases are recognized in the natural history of infection by the human immunodeficiency virus (HIV): (a)an early or acute phase lasting several weeks, (b) an intermittent or chronic phase, with active low-grade viral replication, lasting several years and (c) the final stage or crisis, which corresponds to the clinical phase of AIDS. The virus may enter the nervous system at the time of seroconversion. However the clinical picture of dementia appears later, when there is marked immunodeficiency. HIV enters the nervous system carried in the macrophages, and usually infects the microglia but not the neurons. The physiopathology of dementia is not well known. It is thought that neuronal dysfunction may be mediated by viral proteins and cytokines synthetized by the infected cells and toxic to the neurones.
