Surveys show 9.5 percent of Americans use marijuana;
30 percent of users meet criteria for a disorder.
The percentage of Americans who reported using
marijuana in the past year more than doubled between
2001-2002 and 2012-2013, and the increase in
marijuana use disorder during that time was nearly
as large. Past year marijuana use rose from 4.1
percent to 9.5 percent of the U.S. adult population,
while the prevalence of marijuana use disorder rose
from 1.5 percent to 2.9 percent, according to
national surveys conducted by the National Institute
on Alcohol Abuse and Alcoholism (NIAAA), part of the
National Institutes of Health.
The proportion of users who have a marijuana use
disorder was found to have actually decreased (35.6
percent to 30.6 percent) between 2001-2002 and
2012-2013. Symptoms of marijuana use disorder were
assessed during face-to-face interviews.
“...Given these increases, it is important that the
scientific community convey information to the
public about the potential harms,” said George Koob,
Ph.D., director of NIAAA.
Data about marijuana use was collected as part of
NIAAA’s National Epidemiologic Survey on Alcohol and
Related Conditions (NESARC), a series of the largest
epidemiological surveys of their kind. In total,
79,000 people were interviewed on alcohol use, drug
use and related psychiatric conditions during the
2001-2002 and 2012-2013 surveys.
This analysis appears in the October 21 issue of the
Journal of the American Medical Association (JAMA)
Psychiatry and was led by Bridget Grant, Ph.D.,
Ph.D., (doctorates in psychology and epidemiology)
of the NIAAA Laboratory of Epidemiology and
Biometry.
The marked increase in marijuana use and marijuana
use disorder shown in the study is a significant
change from prior results.
Earlier NIAAA research found that marijuana use
remained stable at about 4 percent of the U.S.
population between 1991-1992 and 2001-2002, while
abuse and dependence rose from 1.2 percent to 1.5
percent.
Marijuana use disorder is defined by the Diagnostic
and Statistical Manual of Mental Disorders.
This includes symptoms such as
- taking the drug in larger amounts or over a longer
period than was intended by the user;
- the persistent desire to cut down or control
use/unsuccessful efforts to do so;
- failure to fulfill major role obligations at work,
school or home as a result of marijuana use;
- and tolerance and/or withdrawal.
“These findings highlight the changing cultural
norms related to marijuana use, which could bring
additional public health challenges related to
addiction, drugged driving and access to effective
treatment,” said Nora D. Volkow, M.D., director of
the National Institute on Drug Abuse (NIDA), which
contributed funding to the study.
The near doubling of the prevalence of marijuana use
disorder among the U.S. population in the last
decade can be attributed to the substantial increase
in marijuana use overall, rather than an increase in
rates of addiction among users.
When examined by age, young adults (ages 18 – 29)
were found to be at highest risk for marijuana use
and marijuana use disorder, with use increasing from
10.5 percent to 21.2 percent and disorder increasing
from 4.4 percent to 7.5 percent over the past
decade.
Black and Hispanic individuals also showed
especially noticeable increases in the prevalence of
marijuana use and marijuana use disorder, with use
increasing from 4.7 percent to 12.7 percent over the
past decade among blacks and from 3.3 percent to 8.4
percent among Hispanics.
The prevalence of marijuana use disorder increased
from 1.8 percent to 4.6 percent among blacks and 1.2
percent to 2.8 percent among Hispanics over the same
time period. All increases were found to be
statistically significant.
Twenty-three states now have medical marijuana laws
and four states, as well as the District of
Columbia, have legalized marijuana for recreational
use.
Studies funded by NIDA and NIAAA have shown that
marijuana impairs driving performance, increasing
lane weaving, and that since the legalization of
medical marijuana in Colorado, drivers involved in
fatal motor vehicle crashes are significantly more
likely to test positive for marijuana use.
With changes in the drug’s legal status at the state
level and a shift in beliefs about the risks
associated with its use, the study authors note that
public education about the dangers associated with
marijuana use, presented in a reasonable and
balanced manner, will be increasingly important to
counteract public beliefs that marijuana use is
harmless.
As marijuana and alcohol are frequently used
together, more research is also needed to understand
the effects of combined use. Studies suggest that
using marijuana and alcohol together impairs driving
more than either substance alone and that alcohol
use may increase the absorption of THC, the
psychoactive chemical found in marijuana.
In June 2015, NIAAA published a study based on
NESARC data showing that alcohol use disorder (AUD)
was on the rise in the U.S. over the last decade.
The results showed that nearly one-third of adults
in the United States have an AUD at some time in
their lives, but only about 20 percent seek AUD
treatment.
For more information
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
http://www.niaaa.nih.gov/.
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