Researchers say that adolescents who are more aggressive also may be more likely to use marijuana or cigarettes, while impulsive youths may be more apt to use alcohol, Reuters reported June 7.

The study also examined possible links between use of alcohol and other drugs and attention-deficit/hyperactivity disorder (ADHD), but found none. Researchers led by Monique Ernst at the National Institute of Mental Health followed 78 12- to 14-year-old youths, 50 of whom had ADHD.

Aggressive youth also were more likely to use substances heavily and also more likely to try new substances.

Researchers said the findings show that varied biological factors may be involved in use of different substances. "Substance-use initiation confers vulnerability for later substance abuse, and a better understanding of its behavioral predictors can help to shape preventive measures at both the individual and societal levels," the researchers said.

The study appeared in the June 2006 issue of the journal Pediatrics.