Having friends who use marijuana (search) or other substances like alcohol and cigarettes is the No. 1 warning sign that a teenager is likely to smoke marijuana as well, a new study suggests.
Researchers looked at what risk factors influence teenagers to start experimenting with marijuana or move from experimental to regular use and found three major risk factors consistently had the biggest impact at all phases of marijuana use among both boys and girls.
At the top of that list is the use of other substances, including alcohol and cigarettes, by the teen or his or her friends. Teens in this category were nearly three times as likely to become regular marijuana users than others.
Two other factors that strongly predicted marijuana use at all stages were delinquency or trouble with the law and school-related problems.
Religious involvement reduced the risk of starting to experiment with marijuana among girls and slightly reduced the risk of transitioning from experimental use to becoming a regular marijuana user.
Risk Factors for Marijuana Use in Teens
In the study, researchers looked at factors associated with marijuana use among a group of more than 13,700 high school students in the U.S. The students ranged in age from 11 to 21 and were surveyed as part of the National Longitudinal Study of Adolescent Health in the USA in 1995 and 1996.
The study showed that more than half of the students who had experimented with marijuana in the first survey continued to use the drug either experimentally or regularly a year later.
Researchers examined the impact of 21 well-established risk factors for adolescent substance use and abuse on five different stages of marijuana use. Three risk factors were the strongest predictors at all stages: the adolescent’s own involvement and peer involvement with substances, delinquency, and school problems.
When all three of these risk factors were present, they increased the risk of a student starting to experiment with marijuana by a factor of 20 over the next year.
Researchers say marijuana use during adolescence is associated with a variety of psychological and health problems.
For example, short-term risks associated with marijuana use among teens include traffic accidents and unprotected sex. Long-term use of marijuana can also reduce their chances of graduating from high school and increases the risk of using other substances and psychiatric problems like depression, anxiety, and suicide.
By Jennifer Warner, reviewed by Brunilda Nazario, MD
SOURCES: van den Bree, M. Archives of General Psychiatry, March 2005; vol 62: pp 311-319. News release, Cardiff University.
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