A cluster of factors becoming more common in people with HIV—older age, diabetes and a large belly—may also increase a person’s risk of developing problems with memory, thinking and learning new tasks, according to two studies presented Tuesday, February 10, at the 16th Conference on Retroviruses and Opportunistic Infections (CROI) in Montreal.

In the early days of the epidemic, moderate to severe AIDS-related dementia was extremely common. In the worst cases, people lost their memories, had disordered thinking, were easily defeated by simple tasks and frequently developed grave psychological and emotional problems. Thankfully, since the introduction of potent combination antiretroviral (ARV) therapy, more severe cases of dementia have become rare.

Some research indicates, however, that a more mild form of cognitive impairment, recently termed HIV-associated neurocognitive disorder (HAND), may occur in up to half of people living with HIV. The disorder can lead people to have milder problems with memory, thinking and learning. These handicaps may cause considerable distress, even if they are not severe enough to compromise daily living. Research in the general population indicates that people with diabetes and other metabolic disorders, such as unhealthy cholesterol levels, could be at higher risk of cognitive impairment.

Two studies presented at CROI looked at potential causes and associations of cognitive impairment in people living with HIV.

The first study was presented by J. Allen McCutchan, MD, from the University of California in San Diego. McCutchan and his colleagues analyzed data involving 145 HIV-positive patients enrolled in the CNS HIV Antiretroviral Therapy Effects Research (CHARTER). Blood sample were taken from all the patients after they hadn’t eaten for 12 hours. Eighty-four percent of the patients were men, and the average age was 46.

McCutchan’s team found that 37 percent of the patients had symptoms of neurocognitive impairment. After controlling for a number of factors, the team found that people who also had type 2 diabetes, people with a large waist circumference and people with an AIDS diagnosis were more likely to suffer from cognitive impairment. In fact, having type 2 diabetes increased the risk by more than sevenfold. Other factors associated with metabolic syndrome, such as abnormal cholesterol or triglycerides, were not linked to neurocognitive impairment.

McCutchan said that his team has not yet analyzed the patients’ medical records to determine whether the use of ARVs known to penetrate the central nervous system (CNS)—drugs such as Viramune (nevirapine), zidovudine (found in Retrovir, Combivir and Trizivir), and abacavir (found in Ziagen and Epzicom)—may have had a protective effect. Nevertheless, he indicated that people with HIV may wish to discuss their HIV treatment options with their providers to determine whether they are on ARV medications that are most likely to get into the CNS, while being the least likely to contribute to diabetes and other metabolic problems. He also recommended healthy diet and weight control.

Age proved to be a significant contributing factor in the second study, which was presented by Jacques Gasnault, MD, from the Hôpital Bicêtre in Le Kremlin Bicêtre, France. Gasnault’s study focused on a small group of HIV-positive patients, all older than 60. In this group, where the average age was 67, Gasnault found that 56 percent had symptoms of cognitive impairment and that the impairment was moderate to severe in 30 percent.

Symptoms of metabolic disorder were common among this group. Nearly 50 percent had high blood pressure, 43 percent had unhealthy cholesterol or triglyceride levels and 27 percent had diabetes. In this study, however, metabolic syndrome was not associated with cognitive impairment to a degree that was statistically significant, meaning that any trend suggesting a link could have occurred by chance. Gasnault recommended that further studies in older people living with HIV should be conducted.