People with HIV might be at much lower risk of brain impairment than a recent study suggested, according to two presentations at the 17th annual conference of the British HIV Association (BHIVA) held April 6 to 8 in Bournemouth, England. The results of the two new studies, reported by the website aidsmap, offer hope to people with HIV and demonstrate the need to understand why brain impairment rates have varied so widely in studies.

A large study of brain impairment in HIV-positive people rocked the research world—and people with HIV alike—when it was first presented two years ago at the Fifth International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention in Cape Town, South Africa. That data, from the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) study, found that 53 percent of the 1,555 HIV-positive people enrolled in the study had at least mild impairment in brain function. Though the level of impairment was so mild in most people that a specialized series of tests were need to diagnose it, these results nevertheless caused much concern about how HIV would affect the brain as people grew older with the disease.

In contrast to the CHARTER findings, the studies presented at the British HIV conference found that brain impairment was barely more common in people with HIV than in their HIV-negative counterparts.

In the first study, looking at HIV-positive adults, researchers at St Mary’s and Hammersmith Hospitals in west London conducted tests on 101 HIV-positive people being cared for in their HIV clinic who had no previous symptoms of brain problems. They found that 19 percent had at least mild impairment. While that number might seem high, it is far less than the 53 percent found in CHARTER and only a bit higher than the 16 percent found in the general public in England.

In the second study, researchers at the same hospital focused on teens who were born with HIV. They compared cognitive function in 31 HIV-positive teenagers with 14 of their HIV-negative siblings. On two of the tests, which focused on an objective measure of brain impairment, the HIV-positive teens were no more impaired than their HIV-negative brothers and sisters. On only one test was the HIV-positive group more impaired, but that test also puts a great deal of weight on how distressed a person feels about potential memory and thinking problems. Given that depression and anxiety are so much more common in people with HIV, and these disorders can cause thinking and memory problems, the researchers reported that this could largely explain the difference between the two groups.

In all, the researchers conclude that the high percentage of people in the CHARTER study with some level of brain impairment might be due to problems other than HIV, problems that were not present in the two newer studies. CHARTER was much larger than the two St. Mary’s studies, however, and so more research will be needed to better understand what is happening in the brains of people with HIV. In the meantime,  the researchers encouraged health care providers to screen for depression and anxiety in people complaining of problems with thinking and memory.