HIV infection linked to premature aging of the brain

HIV infection and its treatments are leading to premature aging of human brains, say researchers.

The study led by researchers from Washington University School of Medicine in St. Louis and the University of California-San Diego showed that blood flow in the brains of HIV patients is reduced to levels normally seen in uninfected patients 15 to 20 years older.

"The graying of the AIDS patient community makes this infection's effects on the brain a significant source of concern," said first author Dr Beau Ances, assistant professor of neurology at Washington University.

"Patients are surviving into their senior years, and a number of them are coming forward to express concerns about problems they're having with memory and other cognitive functions.

"We believe the virus crosses into the brain using infected immune cells.

"Once in the brain, HIV doesn't directly infect neurons but instead affects supporting cells that can release immune factors that harm neurons," Ances added.

During the study, researchers used magnetic resonance imaging scanners and a new technique known as arterial spin labeling that allows precise, non-invasive blood flow measurement.

They recruited 26 subjects with HIV and 25 uninfected controls

When individuals were resting in the scanner, brain blood flow values were significantly reduced in subjects with HIV compared to uninfected controls.

These reductions decreased brain blood flow to levels roughly equivalent to readings seen for uninfected individuals 15 to 20 years older.

When scientists asked participants to perform a visual task, which normally triggers an increase in blood flow to particular regions of the brain involved in the task, participants with HIV had greater blood flow increases, suggesting the brain and its support systems had to work harder to get the task done.

"Brain blood flow levels decline naturally as we age, but HIV, the medications we use to control it or some combination of the two appear to be accelerating this process independent of aging," Ances added.

The study appears online in The Journal of Infectious Diseases.