In November, the National Institute on Drug Abuse (NIDA) launched a new public service announcement aimed at educating teens about the link between drug abuse and HIV infection. Drugs, the ads point out, make people more likely to take risks-like unprotected sex-that can lead to HIV infection.
At a research symposium following the ad campaign's launch, APA Fellow Eileen Martin, PhD, of the University of Illinois-Chicago, discussed her NIDA-funded research on how HIV and drug abuse affect executive brain functions-particularly decision-making.
"Similar brain regions are affected by HIV and drug abuse," Martin said. "They're not identical, but they do overlap." These regions, she said, include areas responsible for judgment, decision-making and impulse control.
To examine how HIV and drug use interact to affect impulse control, Martin tested HIV-positive crack and heroin users and HIV-negative crack and heroin users. The participants played a computerized gambling game in which they could make risky choices that occasionally allowed for large wins but overall led to greater losses, or chose a more conservative strategy that eventually left them with a larger payout.
In the study, published in 2004 in the Journal of the International Neuropsychological Society (Vol. 10, No. 7, pages 931-938), Martin found that the HIV-positive drug users made significantly more risky choices than the HIV-negative drug users, picking from the risky-card pile 47 percent of the time as compared with 40 percent of the time. In comparison, nondrug-using subjects tested in a separate investigation picked the risky card only 37 percent of the time. In other words, Martin said, HIV-positive drug users faced a "double whammy" of loss of impulse control. And, she said, because the groups were matched for factors like age, IQ, and comorbid conditions like attention-deficit hyperactivity disorder and learning disabilities, this difference in impulse control was most likely due to HIV's effects on the brain.
In another study of men who use club drugs like Ecstasy, she found similar results. Men who were both HIV-positive and used the drugs were more likely to make risky choices than men who were HIV-positive alone, or who used club drugs alone.