HIV Patients Face Dementia as They Age

Aging HIV-patients may risk developing chronic dementia similar to Alzheimer's disease, researchers reported Tuesday at the International Conference on Alzheimer's Disease in Philadelphia.

In the normal process of aging, amyloid beta protein is produced that can damage brain cells, but the protein is broken down by the enzyme neprilysin, preventing the damage. However, in HIV patients, the HIV-associated protein Tat blocks neprilysin, allowing the accumulation of amyloid beta, the study found. HIV researchers believe the unchecked accumulation of amyloid beta, in combination with other factors including genetics, can result in slow and devastating memory loss.

The longer a patient had HIV, the more amyloid beta accumulated, regardless of age. Antiretroviral drugs do not appear to slow the dementia, said Lynn Pulliam, a University of California-San Francisco professor of laboratory medicine.

Pulliam and colleagues applied synthetic Tat to normal human brain cells that contained neprilysin, and found a 125 percent increase in amyloid beta in the brain cells. Additionally, they stained brain sections from autopsies of 14 HIV-infected people ages 31-58 with amyloid beta antibodies. They found an increase in amyloid beta among those HIV-infected, compared to the HIV-negative control group.

Memory loss and other problems -- including high cholesterol, arthritis and diabetes -- affect many aging patients of Dr. Kathleen Clanon, medical director for HIV services at Alameda County Medical Center in Oakland. This slow memory loss is very different from the acute dementia in many AIDS patients' final months that physicians saw at the start of the epidemic, said Clanon.

It is not clear yet if new treatments for Alzheimer's patients, such as Aricept, which can temporarily hold off the onset of Alzheimer's, could help HIV patients, said Pulliam.

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