HIV and Psychiatry: Cognitive disorders in people living with HIV disease

Introduction Cognitive complaints are common in HIV disease. Over the course of the HIV epidemic, researchers have come to understand a great deal about cognitive difficulties associated with HIV disease. HIV enters the central nervous system shortly after infection and has a predilection for subcortical brain areas. As the disease progresses, proinflammatory neurotoxins that cause cell injury and cell dysfunction are released. As a result, many people with HIV disease begin to experience difficulties in cognitive functioning. Given the morbidity associated with cognitive disorders for people living with HIV disease, it is essential that practitioners accurately assess changes in mental status. Diagnosis must be grounded in a thorough history and careful psychiatric, mental status, neurologic examination, and where available, neuropsychological examination. Assessment must consider the patient's clinical stage as well as laboratory markers of immune dysfunction and viral burden. What causes the cognitive dysfunction associated with HIV infection? The pathophysiologic mechanism that leads to cognitive dysfunction is unclear, but is thought to be related to HIV replication in the brain, activation of HIV-infected brain microglial cells, liberation of inflammatory neurotoxins (e.g., cytokines, Tumour Necrosis Factor), and impairment in natural host repair mechanisms, ultimately resulting in a level of neuronal dysfunction, injury, or death. The areas most affected are the subcortical brain regions and the fronto-striatal circuitry (Cummings, 1990 ; Parks et al ., 1993 ; Wesselingh et al ., 1994 ; Tyor et al ., 1995 ; Grant and Adams, 1996 ; Masliah et al ., 1997 ; Tan and Guiloff, 1998 ).