Until now there had been little information on how perceived
availability is associated with marijuana use among the general
population and, in particular, for adults, who are the majority of
licensed medical marijuana users.
Because medical marijuana laws are
largely intended for older patients who suffer from illnesses such as
chronic pain or cancer, it was considered likely that medical marijuana
laws affect different age groups differently, and through different
modes of access.
‘Adults over the age of 25 increased marijuana use after their home states made changes to medical marijuana laws. But, no difference in the prevalence of marijuana use was reported among teens.’
Adults over the age of 25 increased their use of marijuana after
their home states made changes to medical marijuana laws, suggested a
new research by scientists at Columbia University's Mailman School of
Public Health. However, there was no difference in the prevalence of
marijuana use reported for 12 to 17 or 18 to 25 year-olds after the laws
The findings are published online in the journal Drug and Alcohol Dependence
The study is the first to link state medical marijuana laws with
marijuana availability and use among adults. Results were based on 10
years of annual survey data from respondents to the National Survey of
Drug Use and Health.
"While the evidence had suggested there is a link between the
passage of laws and increases in marijuana use by those 21 and older, it
was not clear if all sub-groups of adults were influenced in the same
way," said Silvia Martins, associate professor of Epidemiology.
"Before medical marijuana laws changed there was a concern that this
type of legislation could potentially increase recreational marijuana
use in adolescents and adult populations. At least for now, we do not
see an increase in use among adolescents."
The study found that adults 26 years and older increased their
past-month use of marijuana from 5.87% to 7.15% after
medical marijuana laws had passed in their state.
In addition to increasing marijuana use among those 26 years of age
and older, the perceived availability of marijuana also increased after
the laws were passed. And for all age groups, the perception that
marijuana became easily available was higher in states that had passed
medical marijuana laws by 2013.
However, similar to marijuana use, there
was no effect of medical marijuana laws on a change in perception of
availability of marijuana among adolescents (ages 12 to 17) or young
adults (ages 18 to 25) but there was a significant increase in
perceiving marijuana as easily available among those 26 and older, from
59% to 62%.
According to Dr. Martins, while not all states with medical
marijuana laws have enforced patient registration, the number of
patients registered in medical marijuana programs have increased over
time in those states, particularly after 2009 when there were
substantial changes in federal prosecution laws regarding marijuana
cultivation, distribution, and possession.
"Understanding how the passage of medical marijuana laws affects
different age groups improves our understanding of the effects of
marijuana policies and provides information about the types of public
health responses that should accompany major policy changes related to
marijuana," said Martins.