[BEIJING] Scientists have identified a way that HIV causes dementia, which could help in developing drugs to treat the disorder.

The study was published this week (16 August) in the journal Cell Stem Cell.

HIV infection can cause difficulties in memory and learning in patients with advanced disease, a condition known as HIV-associated dementia.

Anti-retroviral drugs are not entirely effective in protecting patients from developing the condition because the drugs cannot successfully reach the brain.

"The brain therefore is a protected reservoir of HIV," says Stuart Lipton from the California-based Burnham Institute for Medical Research.

Lipton and colleagues found that besides killing neural cells, the HIV virus also inhibits the ability of brain cells to regenerate.

Using mice, Lipton and colleagues found that a viral protein called HIV/gp120 prevents 'unprogrammed' brain cells — stem cells — called adult neural progenitor cells, from developing into new brain cells, thus preventing the brain from repairing itself.

The viral protein does this by activating a brain enzyme — p38 MAPK — that blocks brain stem cells from dividing.

Lipton said that a drug that blocks this enzyme could have potential for treating and preventing HIV-associated dementia.

Lu Hongzhou, deputy director of Shanghai Public Health Centre, says now that the Chinese government offers free anti-retroviral treatment to AIDS patients, they live longer and the problem of HIV-associated dementia has become more apparent.

"Previously, many doctors were not aware of the HIV-associated dementia disease, and now, with these kind of studies, doctors can better understand the mechanism of the disease," Lu told SciDev.Net.

Liu Zhe, director of the Nerve Signal Imitation Laboratory at the Beijing Institute for Psychological Medicine, adds that the study might be used by doctors to distinguish different kinds of dementia and to understand the degree of neural diseases.

"But there is a long way before it could be put into clinical practice," Liu told SciDev.Net.

Link to full paper in Cell Stem Cell

Reference: Cell Stem Cell 1, 230 (2007)