Mild brain impairment caused by HIV has become “a silent epidemic” that needs better screening tools and more research to effectively address it, said Dr. Victor Valcour, who presented on HIV and brain injury at a session on long-term complications of HIV and antiretroviral therapy at the 2010 International AIDS Conference.

“The rate of [brain] impairment in patients with HIV is much, much higher” than in the general population, said Dr. Valcour, a physician at the Memory and Aging Center at the University of California in San Francisco, where he is also an Associate Professor in geriatric medicine and neurology.

“About half of patients who have HIV will have abnormal [brain] testing,” he said.

HIV is known to cause damage to the brain that can lead to impairment or, in severe cases, dementia. Brain impairment can involve loss of memory, motor skills, and concentration abilities, as well as behavioral changes and general mental slowness.

Before the advent of highly active antiretroviral therapy (HAART), HIV-associated dementia – the most severe form of HIV-related brain impairment – was fairly common, affecting up to half of people who died of AIDS.

Today, according to Dr. Valcour, “HIV-associated dementia is now quite rare.” However, rates of milder forms of brain impairment have not decreased with HAART and still affect around half of people with HIV.

In many cases, patients may not even realize their brains have been affected, since symptoms may be unnoticeable without specialized testing.

Although the cause of HIV-related brain impairment is not yet known, Dr. Valcour argued that it is an active disease process that continues even when patients are on HAART. This is in contrast to the theory that the impairment is a delayed consequence of damage from earlier in the infection, before treatment begins.

More specifically, Dr. Valcour believes the problem has to do with latent HIV – HIV that remains hidden within the body and is not eliminated by antiretrovirals. Patients who get dementia appear to have higher levels of this latent HIV in their system, even after years of HAART.

The high levels of latent HIV mean that some cells, including immune cells that cross into the brain, still have HIV in them, which may be causing some of the damage to brain cells.

“I think our work is cut out for us to try to figure out ways in which we can attack these [latent HIV] reservoirs and try to clear them, perhaps causing some benefit for [brain] impairment,” said Dr. Valcour.

“We are inadequately treating [brain impairment] with the existing regimens that we have,” he added.

He pointed out that not all antiretroviral drugs are equally effective at reaching HIV in the brain.

“The higher the brain penetration effectiveness of your overall antiretroviral regimen, the more likely you are to have undetectable virus in your CSF [cerebrospinal fluid],” he said. CSF is the fluid that surrounds the brain and spinal cord.

Dr. Valcour finished his talk by stating that work still needs to be done to improve screening and identification of patients affected by brain impairment.

The current specialized tests for determining brain impairment are too complicated and time-consuming to do for everyone, he said, so better screening tools are needed to effectively diagnose minor brain impairment in people with HIV. Ideally, everyone with HIV would then get tested for brain problems.

“If 50 percent of patients who came into your clinic could have a disease, wouldn’t you want to screen everyone? It is a feasibility issue. I think we need to figure out a way to make this work,” he said.

Dr. Valcour also stressed the importance of remaining fit and healthy.

“Things that you as patients can do and you as doctors can recommend: stop smoking, get exercise, treat diseases when they present, [and] be very aggressive about treating depression and psychiatric illness,” he said.

“Patients should remain physically and cognitively stimulated. Physical exercise I think cannot be overstated,” added Dr. Valcour.

For more information, please see the AIDS 2010 webpage on the Kaiser Family Foundation website.