Involvement with other substances (alcohol and cigarettes), delinquency and school problems have been established as the three most important risk factors in identifying teenagers at risk of continued involvement with marijuana by a Cardiff University scientist, in collaboration with a colleague in the USA.

The study, Risk Factors Predicting Changes in Marijuana Involvement, led by Dr Marianne van den Bree, Department of Psychological Medicine, School of Medicine and Dr Wallace Pickworth, National Institute on Drug Abuse (NIDA) in the USA assessed over 13,700 school students at high schools throughout the USA (aged 11-21 years). The students were participating in the National Longitudinal Study of Adolescent Health in the USA twice (in 1995 and in 1996) over a one year period.

Over half of the students in the study who indicated use of marijuana in 1995 were still using it one year later. Twenty-one well-established risk factors of adolescent substance use/abuse, including personality, family variables and religion, were used to predict five stages of marijuana involvement: (1) initiation of experimental use, (2) initiation of regular use, (3) progression to regular use, (4) failure to discontinue experimental use, and (5) failure to discontinue regular use.

Dr van den Bree said: "We found assessment of use of other substances and peer substance use, school, and delinquency factors to be key to identifying individuals at high risk for continued involvement with marijuana. The combined presence of these three risk factors greatly increased risk of experimental (by 20 times) and regular marijuana use (by 87 times) over the next year. Prevention and intervention efforts should focus on these areas of risk."

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Contact: Dr Marianne van den Bree
vandenbreemb@cardiff.ac.uk
44-292-074-4531
Cardiff University
16-Mar-2005