HIV-1 infection and its impact on the HPA axis, cytokines, and cognition

Immediately after infection, Human immunodeficiency virus, type 1 (HIV-1) enters the central nervous system (CNS) and is localized in highest concentration in the hippocampus and basal ganglia. Since these areas are associated with HPA axis and autonomic activities as well as cognition, it has been hypothesized that these functions will be impacted adversely in HIV-1 infection. In the treatment of HIV infection, although the highly potent antiretroviral (HAART) drugs have been effective in reducing peripheral viral load and prolonging life expectancy, these drugs do not cross the blood-brain barrier in therapeutic concentrations. Therefore, it has been proposed that the beneficial effects of HAART on the CNS will be limited. Our investigations on seropositive individuals, showing hypo-reactivity of the autonomic system and HPA axis activity suggest that HIV-1 infection is a model of chronic stress. Furthermore, an elevated baseline TNF-alpha level as well as its increased reactivity to an alpha-adrenergic challenge among HIV-1+ individuals, may lead to additional neurodegeneration. It is proposed that the effects of HIV-1 infection on the brain will have implications for neurocognitive and mental health functioning in seropositive individuals even in patients undergoing HAART therapy. These outcomes may result in the need to develop facilities for long term "care-giving".