Neuropsychopathology in the SIV/macaque model of AIDS

Of the 40 million people living with HIV/AIDS worldwide in 2003, only 7% received highly active antiretroviral treatment (HAART). Without treatment, approximately half of AIDS patients will suffer from NeuroAIDS including neurological dysfunction, peripheral neuropathies, motor impairment, cognitive difficulties and frank dementia. HAART has reduced mortality from AIDS in the developed world, but CNS/neurological complications continue to be a leading cause of death or disability in AIDS patients on HAART. Despite years of use in developed countries, it is still not clear what the long-term impact of HAART will be on NeuroAIDS. The mechanisms of AIDS-related CNS pathology, in the presence or absence of HAART, are not completely understood. Infection with simian immunodeficiency virus (SIV) in macaques provides an excellent research model of AIDS, including AIDS-related CNS pathology and cognitive/behavioral impairments. A major goal of research with the SIV/macaque model has been to characterize behavioral and cognitive impairments in NeuroAIDS and elucidate the CNS pathology behind these impairments. Review of the studies assessing cognitive impairment in SIV infected macaques demonstrates the high concordance between neuropsychological impairment in human and simian AIDS. Consistent with results in human AIDS patients, SIV-infected monkeys tend to be impaired most often on tasks dependent upon intact frontal cortical and/or subcortical functioning. Building on the strengths of the SIV/macaque model of AIDS, directions for future research are discussed including further mechanistic studies of the neuropathology leading to cognitive impairment as well as assessment of the impact of antiretroviral therapy or drugs of abuse on NeuroAIDS.