HIV treatment may not fully protect the brain or eliminate the risk of impaired brain functioning, according to a new study published in the September issue of AIDS and reported today by AIDSmap. A separate AIDSmap report, highlighting data in September’s Archives of Neurology, suggests that a drop in platelets in people with advanced HIV disease may be a predictor of dementia occurring within six to 12 months.
According to the ongoing AIDS Clinical Trials Group (ACTG) ALLRT study, antiretroviral therapy has not been highly effective at reversing or preventing neurological problems in 1,160 HIV-positive people. The ALLRT participants, recruited from 14 other ACTG studies in which various treatment regimens were being evaluated, are tested for cognitive impairment at least 20 weeks after starting HIV therapy—their official ALLRT starting point—and then every 48 weeks after that.
During their first round of cognitive testing in ALLRT, 39 percent of the volunteers had mild or mild-to-moderate cognitive impairment. Despite ongoing treatment, more than half remained impaired during the follow-up period, whereas 44 percent experienced cognitive improvements. What’s more, 21 percent who entered ALLRT with normal cognitive functioning became impaired during follow up while on antiretroviral therapy.
Researchers found that the risk for cognitive impairment was higher in people who started HIV treatment with low CD4 counts or who were older than 55 years old. “Additional studies,” the authors write, “are needed to understand the mechanisms behind neurocognitive impairment and to develop strategies to prevent and treat this condition.”
The second study, conducted by the North East AIDS Dementia Cohort, recruited 146 people who had advanced HIV disease and mild cognitive impairment. Seventy-eight percent of them were on antiretroviral therapy. Researchers found that participants with declining platelet counts—a condition called thrombocytopenia—were twice as likely to develop HIV-related dementia than those whose platelet counts remained stable. Additional research is needed to determine whether these results will be broadly applicable to most people with HIV.
While it is not clear why antiretroviral treatment is not fully protective against dementia, Kevin Robertson, PhD, of the University of North Carolina, and his ACTG colleagues suggest that many HIV drugs do not easily cross the blood–brain barrier and therefore fail to completely suppress viral reproduction—and the damage it causes—in the brain.