Heavy marijuana use can be a problem for teens and adults, but Swiss researchers concluded that occasional use of the drug did not appear to cause psychosocial problems for adolescents, the West Australian reported Nov. 6.

Researcher J.C. Suris and colleagues at the University of Lausanne studied marijuana use among more than 5,200 Swiss teenagers and concluded that those ages 16-20 who used marijuana once or twice a month "don't have great additional problems. They are kids who function well," according to Suris.

Light users of marijuana were found to be more likely to play sports and have good relationships with friends than non-users, according to the self-reported survey. Marijuana users were more likely to skip school than abstainers, but reported that their grades were just as good.

However, researchers found that teens who smoke cigarettes as well as marijuana tend to have more problems, including more heavy use of the drug, less participation in sports, and poorer grades in school. Marijuana users also were also less likely to report having a good relationship with their parents than non-users.

The study was published in the November 2007 issue of the Archives of Pediatrics and Adolescent Medicine.