Columbia: Legalizing medical marijuana has not increased recreational use of the
substance among U.S. adolescents, according to a new study conducted at
Columbia University’s Mailman School of Public Health. The findings are published online in the journal Addiction. “For
now, there appears to be no basis for the argument that legalizing
medical marijuana has increased teens’ use of the drug,” says Deborah Hasin, PhD, professor of Epidemiology
at Columbia’s Mailman School and senior author of the study. “However,
we may find that the situation changes as commercialized markets for
medical marijuana develop and expand, and as states legalize
recreational marijuana use.”
The researchers analyzed the
results of eleven separate studies dating back to 1991 using data from
four large-scale U.S. surveys: Monitoring the Future, National
Longitudinal Survey of Youth, National Survey on Drug Use and Health,
and the Youth Risk Behavior Survey. No significant changes, increases,
or decreases occurred in adolescent recreational use following enactment
of medical marijuana laws.
In 1996, California became the first
U.S. state to legalize marijuana use for medical purposes. Medical
marijuana is now legal in 29 states. Opponents of medical marijuana have
argued that such laws increase recreational marijuana use among
adolescents.
Far fewer studies have examined the effects of
medical marijuana laws among adults, according to Hasin, who is also a
professor in the Department of Psychiatry at Columbia University Medical Center.
“Although we found no significant effect on adolescent marijuana use,
existing evidence suggests that adult recreational use may increase
after medical marijuana laws are passed.” She continues, “The $8 billion
cannabis industry anticipates tripling by 2025. Obtaining a solid
evidence base about harmful as well as beneficial effects of medical and
recreational marijuana laws on adults is crucial given the intense
economic pressures to expand cannabis markets.”
Hasin also
points out that the intensity of marijuana use in teens has not been
explored thoroughly. “This warrants additional consideration, especially
with the decreasing national trend of risk perception among adolescents
and as the current perception gives rise to more medical marijuana
stores and commercial opportunities.”
The first author of the
paper is Aaron L. Sarvet. Co-authors are Melanie M. Wall, Katherine M.
Keyes, David S. Fink and Emily Greene, Mailman School of Public Health;
Aline Le, Columbia University Medical Center; Anne E. Boustead,
University of Arizona; Rosalie Liccardo Pacula, Rand Corp.; Magdalena
Cerdá, University of California, Davis; and Sandro Galea, Boston
University.
The study was supported by the National Institute on
Drug Abuse (R01DA034244, R01DA040924, K01DA030449, T32DA031099),
National Institute on Alcohol Abuse and Alcoholism (K01AA02151, and by
the New York State Psychiatric Institute.