Although psychostimulant abusers comprise one of the fastest growing populations of HIV-infected patients, relatively little is known about how HIV may impact the rewarding effects of abused drugs. Dr. Jay P. McLaughlin discusses how a protein associated with HIV infection, called HIV-1 Tat, may increase vulnerability for drug addiction. His research shows that mice who express HIV-1 Tat display an enhanced sensitivity to the rewarding properties of cocaine. The results suggest that just as addiction raises the risk of HIV, HIV may raise the risk of addiction.