Cannabis Withdrawal and Dependence Is Real, Study Says

More than 80 percent of study participants met criteria for 'cannabis dependence.'

Marijuana image via shutterstock

Marijuana image via shutterstock

While many proponents claim marijuana is nonaddictive, a new study by Massachusetts General Hospital (MGH) researchers may have just found otherwise. Perhaps it’s not so easy being green.

According to the new study, which is published in the Journal of Addiction Medicine, 40 percent of cannabis-using adolescents in the study reported experiencing symptoms of withdrawal. Although reporting withdrawal makes individuals more likely to meet criteria for severe substance use and mood disorders, “the presence or absence of withdrawal did not appear to change long-term treatment outcomes,” the researchers noted in the report.

“Our results are timely given the changing attitudes and perceptions of risk related to cannabis use in the U.S.,” says John Kelly, PhD, of the Center for Addiction Medicine in the MGH Department of Psychiatry, senior author of the study. “As more people are able to obtain and consume cannabis legally for medical and, in some states, recreational use, people are less likely to perceive it as addictive or harmful. But research shows that cannabis use can have significant consequences, and we know that among adolescents it is second only to alcohol in rates of misuse.”

The researchers note that there have been previous studies that looked at the incidence of cannabis withdrawal in adolescents, but none that followed-up as extensively as this new study.

According to a report by MGH:

Few [other studies] have included follow-up periods longer than 30 days or examined the relationship of withdrawal to factors such as the severity and consequence of cannabis use and the presence of other psychiatric symptoms. The current study enrolled 127 adolescents between ages 14 and 19 being treated at an outpatient substance use disorder clinic, 90 of whom indicated that cannabis was the substance they used most frequently.

Upon entering the study and at follow-up visits 3, 6 and 12 months later, participants received comprehensive assessments including interviews by study staff and completion of survey instruments analyzing factors related to substance use – including whether or not they thought they might have a problem with drug use – withdrawal symptoms, consequences in their lives attributable to substance use, and other psychiatric symptoms and diagnoses. Based on their answers, participants were divided into two groups – those who reported cannabis withdrawal symptoms such as anxiety, irritability, depression and difficulty sleeping and those who did not.

The study looked at 90 cannabis-using participants, and found among them that more than three-quarters (76 participants; 84 percent) met criteria for cannabis dependence. “Dependence,” according to researchers, is defined as “increased tolerance and use of cannabis, unsuccessful efforts to reduce or stop using, and persistent use in spite of medical and psychological problems made worse by cannabis.”

Withdrawal symptoms were reported by 36 participants—40 percent of the overall group—and all also met criteria for dependence.

When the study began, participants who reported withdrawal symptoms were more likely to have missed work or school and had financial and relationship problems due to their substance use. These individuals were also more likely to have mood disorders.

Still, those who recognized that they had a problem with cannabis had a better outcome than those who did not.

While the presence of withdrawal symptoms is a strong indicator of cannabis dependence, the authors note, it did not significantly impact the ability of participants to reduce their use of cannabis during the 12-month follow-up period. The factor that did appear to make a difference was whether or not an individual recognized having a problem with substance use upon entering the study. Participants who both reported withdrawal symptoms and recognized having a problem had a small but steady improvement in abstinence through the entire study period. Those who reported withdrawal symptoms but did not recognize a substance use problem had a slight increase in abstinence in the first 3 months, but then had some increase in cannabis use during the subsequent 9 months, a pattern that was also seen in participants not experiencing withdrawal.

“We hypothesize that participants who experience withdrawal symptoms but do not recognize having a substance use problem may not attribute those symptoms to cannabis withdrawal,” says Claire Greene, the corresponding author of the report who formally worked at MGH’s Center for Addiction Medicine. “Those who do acknowledge a substance-use problem may correctly attribute those symptoms to cannabis withdrawal, giving them even more motivation to change their substance use behavior.”

Kelly says that more research is needed on cannabis misconceptions and use disorders. “The importance of understanding the addictiveness, risks and harms associated with cannabis use is a major theme of this study’s findings. Recognizing those risks is known to reduce the likelihood that someone will start to use drugs, and better understanding of the role of substances in the problems experienced by patients may help them cut down on future use. Unfortunately, the general trend in attitudes in the U.S. is to minimize the risks and not recognize the addictiveness of cannabis.”