Of the estimated 40 million adults and children worldwide who are living with HIV infection, an estimated 27 million live in sub-Saharan Africa, according to Sacktor.

"If the rate we saw in our study translates across sub-Saharan Africa, were looking at more than 8,000,000 people in this region with HIV dementia," says Sacktor.

Sacktor says an extremely high rate of HIV dementia in Africa and other poor regions of the world adds enormously to the social and economic burden of their populations and governments. Dementia not only disrupts jobs and adds to the cost of care, but also interferes with a patients ability to adhere to a regular course of antiretroviral medication, thus increasing the risk of drug resistance. People with dementia also are less likely to practice safe sex.

Before antiretroviral medications were available in the United States, the U.S. rate of HIV dementia was similar to what was discovered in this study in Uganda, says Sacktor. Unfortunately, he says, only 20 percent of people infected with HIV in the world are getting treatment.

"We hope studies like these will shed additional light on the devastating problem of HIV in resource-limited countries like Uganda and encourage more programs that bring much-needed medication to these poor regions of the world," Sacktor says.

Sacktor says theres little accurate data about HIV dementia patients in other parts of the world --- current estimates of the number of HIV-positive patients who have dementia range from 9 percent to 54 percent.