New UCLA study looks at HIV's role in brain aging
When the first reported cases of HIV sprang up in the early 1980s, all research efforts focused on keeping patients alive. At the time, the prognosis was grim. Scientists were working fast to understand how it was transmitted, and treatments did very little. Most people only lived a year or two beyond the time they were diagnosed. By 1994, AIDS — the syndrome HIV leads to — had become the most common cause of death for all Americans ages 25 to 44.
Starting in the mid-1990s, a number of therapies were developed that would change the course of people’s lives with HIV. While there is still no cure today, HIV can be well-controlled through combination antiretroviral therapy (cART). “It’s one of the great triumphs of modern public health,” says Harry Vinters, MD, a neuropathologist at UCLA.
As a result, the number of older adults with HIV is growing. In fact, nearly half of people who have been diagnosed with HIV in the United States are ages 50 and older. That’s led to a whole new set of research questions related to HIV.
Understanding cognitive impairment
A team of researchers at UCLA recently looked at the effects of long-term HIV infection on brain aging.
A sizable percentage of older people with HIV have HIV-associated neurocognitive disorder (HAND). This affects areas such as brain function, motor skills, mood and behavior. How HAND develops is unknown.
The most serious form of HAND, known as HIV-associated dementia, now occurs in less than 5% of people who are on cART. However, many people experience milder symptoms. These include:
- Behavioral changes
- Difficulty in making decisions
- Memory loss
- Trouble with learning, attention and concentration
“We don’t really know what’s causing the cognitive impairment many people living with HIV have,” says UCLA neuropathologist Shino Magaki, MD, PhD.
An under-studied group
Scientists believe that inflammation in the brain plays a role in aging and neurodegenerative diseases such as Alzheimer’s disease. Yet, it’s not clear whether HIV speeds up aging or increases the risk for Alzheimer’s.
To tackle this question, the team of researchers from UCLA — including Dr. Vinters and Dr. Magaki — examined the brains of 16 older adults. Seven were HIV-negative, and nine were HIV-positive. They also did not have hepatitis C.
This is an important group to study, notes Dr. Magaki. That’s because much of the previous research has been done on people who are in an active phase of HIV infection. “The brains of elderly individuals who are well controlled on cART haven’t been looked at as much,” she says. “We wanted to isolate the long-term effects of HIV infection, without HIV encephalitis, to see if there was something detectable that would help explain their cognitive impairment.”
The study relied on the National Neurological AIDS Bank (NNAB), part of the National Neuro-AIDS Tissue Consortium. The NNAB is headed up by UCLA neurologist Elyse Singer, MD. The bank includes people with HIV and AIDS who have agreed to be examined and donate samples throughout their life.
How HIV and dementia interact
Researchers looked at cells in the brains of the subjects under the microscope. They did not find any differences between those who had HIV and those who didn’t. This likely means that the cause of cognitive impairment in people with HIV has multiple factors that are hard to detect.
“There’s no evidence that HIV infection worsens Alzheimer’s disease changes in the brain to the extent that we can look for those with the tools we have,” Dr. Vinters says.
The results of the study were published in the Journal of Neuropathology & Experimental Neurology. In the future, researchers would like to look more in-depth at the cellular level. They might find, for example, that while HIV-positive and HIV-negative subjects have the same number of certain types of cells, the function of those cells may differ. They would also like to examine a bigger group of people.
“This is important to study because it’s hard to come up with treatments [for a condition] when you don’t understand what’s causing it,” Dr. Magaki says. “Right now, we don’t have good treatments other than keeping HIV under control.”
Despite the mysteries that remain, HIV research and treatment have come a long way. Now that many HIV-positive individuals are living long lives, there’s more to learn about how to keep them as healthy as possible as they age.
“When I first started working on HIV when the epidemic began, sadly patients weren’t living very long,” Dr. Vinters says. “It was not an issue of what happens to AIDS patients when they get older because they didn’t get older. Happily, that’s changed.”
To learn more about HIV research, visit CARE, the UCLA Center for Clinical AIDS Research and Education.