HIV and antiretroviral therapy: impact on the central nervous system.

The HIV pandemic represents a major source of neurological morbidity worldwide. Emerging data from diverse populations indicate that HIV leads to significant neurocognitive impairments that reduce individuals' ability to contribute to the well being of their families and society. HIV affects vulnerable populations with many comorbidities, but the virus contributes to neurocognitive impairment independent of these conditions. The neuropathological substrate of HIV neurocognitive disorders is damage to synapses and dendrites, without major neuronal loss. This suggests the potential for substantial reversibility if synaptodendritic function can be restored. In the developed world, combination antiretroviral therapy (CART) leads to improved neurocognitive function as well as morbidity and mortality in HIV. CART is being used in increasing numbers of individuals in resource limited settings. New cases of severe dementia are now rare in populations where effective CART has been deployed. While some degree of neurocognitive improvement with CART is almost universal, many individuals do not achieve full restoration of their premorbid neurocognitive status, and milder degrees of impairment remain quite prevalent. Optimizing neurocognitive recovery is likely to require the development of better CNS penetrating antiretroviral regimens and the use of neuroprotective agents.