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Report: Cognitive Impairment in People Living With HIV/AIDS

Even though people living with HIV/AIDS (PLWHA) can often show cognitive impairment, the good news is that they do not appear to experience accelerated cognitive decline as they age, according to new research presented at the Conference on Retroviruses and Opportunistic Infections (CROI) last month in Seattle.

While AIDS-associated dementia is now very rare for PLWHA who are on antiretroviral treatment (ART), some people still experience more subtle cognitive problems and can have abnormalities in brain structure, which can often only be revealed through specialized testing. Hamza Coban, a researcher from the University of San Diego, conducted a study to see if these cognitive problems became more acute with age, a new pressing concern now that more than half of people living with HIV in the U.S. are over the age of 50.

Coban looked at the relationship between age and neurocognitive performance over time, comparing changes in older and younger individuals who had been on ART for at least 2 years. The researchers analyzed 3,313 people who were part of the AIDS Clinical Trials Group (ACTG) cohort.

Participants were given different neurocognitive assessments to test cognitive performance, including memory. Overall performance was summarized using scores that were standardized against results from the general population of the same age.

At the time of the first neurocognitive test, more than 90 percent of those in the study were on ART treatment and had a suppressed viral load. Initial testing found that 42 percent of participants showed verbal impairment and 39 percent showed overall impairment.

Coben found that the odds of neurocognitive impairment increased with age, with an 18 percent increase in impairment for each decade older of a participant. PLWHA who were 31-40 years old when they began ART were significantly associated with poorer neurocognitive test results than their younger counterparts. Age-related impairment was seen despite viral suppression.

Researchers hypothesized that the causes of age-related neurocognitive impairment might include ART worsening common age-related conditions such as diabetes, hypertension and abnormal blood lipids, and inducing more central nervous system toxicities in older people. However, much more research is needed to understand the relationship between HIV and cognitive impairment.

Although Coben’s study found more acute cognitive decline in PLWHA than those who were HIV-negative, age related cognitive decline is normal in the general population as well. James Cole, from Imperial College, London, initiated a different study to see if cognitive decline was accelerating, moving at a much faster rate for PLWHA than for the general population.

His study analyzed data from HIV-positive participants in the European COBRA (Comorbidity in Relation to AIDS) collaboration and a group of demographically similar HIV-negative people to see whether successfully treated HIV is associated with accelerated age-related changes to brain structure and function.

The analysis included 134 HIV-positive individuals and a control group of 79 HIV-negative people of a similar age and gender distribution. Patients were given magnetic resonance imaging (MRI) and neuropsychological evaluations, which tested language, memory, executive function, motor function and processing speed. Then the patients were given these same tests two years later.

MRIs showed that people with HIV had less brain grey matter volume and abnormal white matter microstructure compared to HIV-negative people, as well as poorer cognitive function. However, when the tests were performed two years later, there were no notable differences in age-related changes in the HIV-positive and HIV-negative groups. Both groups showed declines in neuroimaging measures. HIV-positive people lost 0.82 percent of their brain volume per year while HIV-negative people lost 0.77 percent, which is not a significant difference.

“HIV-positive people with suppressed virus on combination ART had abnormalities in measures of brain structure and function at baseline," the authors of the study wrote. "But there was no difference in the dynamics of these measures over time between [HIV-positive] and HIV-negative controls."

Even though previous research found evidence for increased cognitive decline in PLWHA, the study found no evidence for brain aging to be accelerated over time for people who are on ART treatment.

"No evidence of ongoing brain injury or overall cognitive decline were detected," said Ryan Sanford, from the Montreal Neurological Institute at McGill University, who led a similar study to Cole. "These findings support the hypothesis that cognitive and structural brain differences in HIV-positive patients most likely occur during the period of untreated infection, suggesting a possible neurocognitive benefit from early combination ART initiation."

Sanford and Cole’s research suggests that the neurocognitive decline occurs before PLWHA begin ART treatment, but stops declining once viral levels are suppressed, underscoring how important it is for HIV-positive people to start treatment as soon as possible.