Brain Aging in HIV-1 Infection

Abstract

It has been shown that patients carrying HIV-1 accumulate damage to cells and tissues that are not directly infected by the virus itself (e.g., neurons). Importantly, these include changes known as HIV-Associated Neurodegenerative Disorder (HAND) leading to the loss of neuronal functions. HAND is an outstanding problem in the clinical management of HIV-1 patients because suppression of infectious virus by cART does not completely block neurodegenerative changes. Neuropsychological studies disclose cognitive alteration (such as loss of Spatial and Declarative Memory) in a substantial proportion of HIV-1 infected patients, and analysis of post-mortem brain tissues isolated from HIV-1 patients treated with cART show signs of neurodegeneration. In the absence of HIV-1 infection of neurons, several mechanisms have been proposed for HAND, including indirect inflammatory effects in the CNS and direct effects of viral proteins (e.g., gp120) shed from activated HIV-1-infected cells. The fact that these viral proteins enter the neurons through several pathways suggests the presence of many competing mechanisms that can contribute to HAND, each of which has its advocates. Their relative contributions to clinical disease in vivo remain to be sorted out, and this is an outstanding problem in HIV research. This chapter will shed some light on the mechanisms used by HIV-1 leading to memory impairments and premature brain aging.