A new study shows that an HIV drug can reverse memory loss. Humans use this type of memory to associate names with faces. It begins to decline in middle age.

SACHA PFEIFFER is the host.

A drug used to treat HIV aids may have another use. At least in mice, it appears to reverse a form of memory loss. Jon Hamilton reports that the finding suggests a new approach to treating brain changes associated with aging or disease.

As a brain gets older, it can still form new memories, but it has trouble linking them together. The problem is explained by Alcino Silva, a neuroscientist at the University of California, Los Angeles.

ALCINO SILVA: You learn about something, but you can't remember where you heard it. You don't remember who told you. As we get older, these incidents happen more and more.

Scientists have known that for a long time.

What we haven't known is how the brain does this.

Silva's lab was studying a molecule that helps the brain separate recent memories from older ones. Silva didn't think that this molecule could play a role in memory problems associated with aging.

But we checked and voila.

The process that helps us do things like link a name and face can be interfered with by the increase in levels of CCR5.

You no longer link memories after that because the molecule turns off memory mechanisms.

Silva's lab showed in mice that blocking the CCR5 could restore memory linking, but they wanted to do it in people as well.

There is an FDA-approved drug, which is unbelievable luck.

There is a drug called maraviroc. It prevents HIV from entering immune cells.

We gave this drug to middle age animals and it gave you the same thing. It was able to restore memory linking.

The results are limited to mice, but they hold promise for older people and stroke patients. A few years ago, Silva and Dr. Thomas Carmichael did a study that showed a big increase in levels of CCR5 after a stroke. In the short term, it helps brain cells survive.

The problem is that when the systems stay active, they limit the ability of the brain cells to recover.

The cells cannot form the new links needed to carry out tasks like moving an arm or a leg. The mice who got maraviroc did not have this problem. The team found that stroke patients with naturally low levels of CCR5 recovered faster. The findings show that a drug like maraviroc could help people with a wide range of brain problems.

You might have an effect on Alzheimer's disease, stroke and Parkinson's disease.

A team is studying maraviroc in people who have had a stroke. Jon Hamilton is a reporter for NPR.

All rights reserved All rights belong to the person. The terms of use and permission pages can be found at www.npr.org.

A rush deadline is when NPR transcripts are created. This text may be revised or updated in the future. Availability and accuracy may be different. The audio record is the authoritative record of NPR's programming.