Adolescent rats more vulnerable to drug addiction than adults; younger animals consumed more cocaine and worked harder for it than did adults

Earlier use of cocaine is associated with more severe addiction; however, it has been unclear whether this was due to more opportunities for drug exposure or increased sensitivity to addiction in young people.

To answer this question, researchers directed by Michela Marinelli, PhD, at Rosalind Franklin University of Medicine and Science trained adolescent and adult rats to poke their noses into a small hole to obtain cocaine intravenously. Over a wide range of doses, adolescent rats learned how to get cocaine more readily than did the adults, and they also took more cocaine overall. In addition, when the researchers made cocaine harder to get, the adolescent rats worked two to three times harder than the adults to obtain the drug.

"Our study shows, for the first time, that adolescents are more sensitive to lower doses of cocaine, and they will work harder to obtain it," Marinelli said. "Our research is the first to offer scientific evidence that when all opportunities to take drugs are equal, biology alone makes adolescents more likely to use cocaine compared to adults," she said.

Research was supported by the National Institute on Drug Abuse and the American Recovery and Reinvestment Act.