Research by a group of scientists studying the effects
of heavy marijuana use suggests that
withdrawal from the use of marijuana is similar to what is
experienced by people when they quit
smoking cigarettes. Abstinence from each of these drugs
appears to cause several common symptoms,
such as irritability, anger and trouble sleeping, based on
self-reporting in a recent study of 12 heavy
users of both marijuana and cigarettes.
"These results indicate that some marijuana users
experience withdrawal effects when they try
to quit, and that these effects should be considered by
clinicians treating people with problems
related to heavy marijuana use," said lead investigator
Ryan Vandrey, of the Department of Psychiatry
at the Johns Hopkins School of Medicine.
Marijuana is the most widely used illicit drug in the
United States. Admissions in substance
abuse treatment facilities in which marijuana was the
primary problem substance have more than
doubled since the early 1990s and now rank similar to
cocaine and heroin with respect to total number
of yearly treatment episodes in the United States, Vandrey
says.
He points out that, until recently, a lack of data has
led to cannabis withdrawal symptoms not
being characterized or included in medical reference
literature such as the Diagnostic and Statistical
Manual of Mental Disorders, 4th Edition (DSM-IV) or the
International Classification of Diseases,
10th Edition (ICD-10).
Since the drafting of the DSM-IV in 1994, an
increasing number of studies have surfaced
suggesting that cannabis has significant withdrawal
symptoms. What makes Vandrey's recent study
unique is that it is the first study that compares
marijuana withdrawal symptoms to withdrawal
symptoms that are clinically recognized by the medical
community--specifically the tobacco withdrawal
syndrome.
"Since tobacco withdrawal symptoms are well-documented
and included in the DSM-IV and the
ICD-10, we can infer from the results of this comparison
that marijuana withdrawal is also clinically
significant and should be included in these reference
materials and considered as a target for
improving treatment outcomes," Vandrey said.
Vandrey added that this is the first "controlled"
comparison of the two withdrawal syndromes
in that data was obtained using rigorous scientific
methods: Abstinence from drugs was confirmed
objectively, procedures were identical during each
abstinence period, and abstinence periods occurred
in a random order. Another strength of the study is that
tobacco and marijuana withdrawal symptoms
were reported by the same participants, thus eliminating
the likelihood that results reflect
physiological differences between subjects.
Interestingly, the study also revealed that half the
participants found it easier to abstain from
both substances than to stop marijuana or tobacco
individually, whereas the remaining half had the
opposite response.
"Given the general consensus among clinicians that it
is harder to quit more than one substance
at the same time, these results suggest the need for more
research on treatment planning for people
who concurrently use more than one drug on a regular
basis," Vandrey said.
Vandrey's study, which appears in the January issue of
the journal Drug and Alcohol
Dependence, followed six men and six women at the
University of Vermont and Wake Forest
University School of Medicine for a total of six weeks. All
were over 18 (median age 28.2 years), used
marijuana at least 25 days a month and smoked at least 10
cigarettes a day. None of the subjects
intended to quit using either substance, did not use any
other illicit drugs in the prior month, were not
on any psychotropic medication, did not have a psychiatric
disorder and, if female, were not pregnant.
For the first week, participants maintained their
normal use of cigarettes and marijuana. For
the remaining five weeks, they were randomly chosen to
refrain from using cigarettes, marijuana or
both substances for five-day periods separated by nine-day
periods of normal use. In order to confirm
abstinence, patients were given daily quantitative urine
toxicology tests of tobacco and marijuana
metabolites.
Withdrawal symptoms were self-reported on a daily
basis Monday through Friday using a
withdrawal symptom checklist that listed scores for
aggression, anger, appetite change, depressed
mood, irritability, anxiety/nervousness, restlessness,
sleep difficulty, strange dreams and other, less
common withdrawal symptoms. Patients also provided an
overall score for discomfort they experienced
during each abstinence period.
Results showed that overall withdrawal severity
associated with either marijuana or tobacco
alone was of similar frequency and intensity. Sleep
disturbance seemed to be more pronounced during
marijuana abstinence, while some of the general mood
effects (anxiety, anger) seemed to be greater
during tobacco abstinence. In addition, six participants
reported that quitting both marijuana and
tobacco at the same time was more difficult than quitting
either alone, whereas the remaining six
found it easier to quit marijuana or cigarettes
individually than to abstain from the two
simultaneously.
Vandrey recognizes that the small sample size is a
limitation in this study, but the results are
consistent with other studies indicating that marijuana
withdrawal effects are clinically important.
This study was conducted while Vandrey was a doctoral
candidate at the University of Vermont.
It was supported by grants from the National Institute on
Drug Abuse.
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