HIV and Dementia Connection Explained

Patients living longer with HIV/AIDS are at risk to develop a condition called HIV-associated dementia (HAD). Scientists have discovered that some people diagnosed HAD actually have two genetically different HIV types in their bodies, hiding in a place where HIV has never been seen before.

Scientists at the University of Chapel Hill wanted to explain the link between the virus and the neurological condition. Their findings might help identify who is at greatest risk for HAD.

AIDS patients should watch for signs of HIV-associated dementia.

The HIV types were identified in the cerebrospinal fluid (CSF), the clear fluid found around and inside the brain and spinal cord. What was interesting to scientists is that they were not identified in the patient's blood, where the virus typically develops, but it could be found in the CSF years before the onset of the condition. This suggests that the virus grows in the central nervous system.

The study had another unusual finding. One of the HIV types infects and replicates in macrophages, a type of white immune blood cell. It's the first time that HIV has been discovered to replicate outside of immune system T cells, according to study author, Dr. Richard Swanstrom.

The scientists used blood and CSF samples from patients who either had HIV-associated dementia or other severe neurological issues. When therapy was applied, the virus in half of the samples decayed much slower than would be expected with immune system T cells. That gave scientists the clue that the virus was produced by a different kind of cell.

Swanstrom and his colleagues are following up their findings with more research. The study was published in PloS Pathogens in October 2011.

Funding was provided by a National Institutes of Health grant.