The study included 26 adults with HIV (the virus that causes AIDS), aged 40 and older, who were given mental performance and driving simulator tests.
The level of the virus in the HIV-positive patients' blood did not affect their driving performance, but being older was associated with poorer driving skills and slower visual processing speed, the researchers said.
The study was published recently in the Journal of the Association of Nurses in AIDS Care.
This area requires further research because by 2015, nearly half of the people with HIV in the United States will be 50 or older, said principal investigator David Vance, associate director of the Center for Nursing Research at the University of Alabama at Birmingham.
"Driving is perhaps one of the most [mentally] complex everyday activities, involving the ability to successfully negotiate one's environment on the road by making quick decisions and attending and reacting to various stimuli," he said in a university news release.
"The most pronounced and prevalent [mental] deficits in HIV are found in measures of speed and processing -- functions essential to safe driving," Vance said.
Although the study found that older HIV-positive people showed signs of impaired driving, it did not prove a cause-and-effect relationship.
"Previous research shows 29 percent of adults with HIV have indicated a decreased driving ability. That alone means it's an area that requires further examination," Vance said.
The U.S. National Institute of Allergy and Infectious Diseases has more about HIV/AIDS.