Adolescent rats given cocaine were more likely to return to the place where they got the drug than adult rats, suggesting that younger drug users may be more likely to be motivated by drug-related cues than older users, Biology News reported April 21.

The younger rats also returned to the drug-administration site after a small dose of cocaine was administered after the drug-linked preference was discontinued. It took researchers 75 percent more trials to extinguish the conditioned place preference of the adolescent rats, and the young rats were 40 percent more likely to reinstate their place preference than adult rats when a low "priming" dose of cocaine was administered after a 24-hour delay.

"Adolescent vulnerability to addiction involves robust memories for drug-associated cues that are difficult to extinguish," the researchers from McLean Hospital in Massachusetts wrote.

The study was reported in the April 2008 issue of the journal Behavioral Neuroscience.