Nearly Half of Regular Cannabis Users Experience Withdrawal Symptoms

By Linda Carroll

April 14, 2020

(Reuters Health) - Nearly half of regular cannabis users who opt to quit or don't have access to the drug may experience withdrawal symptoms that can include irritability, anxiety, sleep disturbance, headaches, nausea and abdominal pain, a new meta-analysis shows.

Researchers found that 47% of those trying to quit or who didn't have access to the drug suffered from cannabis withdrawal syndrome (CWS), according to the report in JAMA Network Open.

"We were not surprised to find that the prevalence of CWS was high," said lead author Dr. Anees Bahji, a PGY5 resident in psychiatry at Queen's University in Kingston, Ontario. "However, we found that some of the characteristics of CWS are consistent with other substance use disorders, which really serves to legitimize the decision to classify CWS and cannabis use disorders as psychiatric conditions."

"Hopefully this article will encourage discourse and dialogue between people who use cannabis with physicians, friends and family," she said in an email. "Perhaps it will also raise awareness among users of cannabis. Ideally, this study will help legitimize the experiences of CWS among those who use cannabis."

To take a closer look at CWS, Bahji and her colleagues combed through the medical literature. Out of 3,848 unique abstracts, 86 were selected for full text review. Those were winnowed down to 47, which included a total of 23,518 participants, with a median age of 29.9. Most, 72%, were white and male, 69%.

The researchers used the DSM-5 definition of CWS, which requires the presence of at least three of the following symptoms within seven days of reduced cannabis use: (1) irritability, anger or aggression; (2) nervousness or anxiety; (3) sleep disturbance; (4) appetite or weight disturbance; (5) restlessness; (6) depressed mood; and (7) somatic symptoms, such as headaches, sweating, nausea, vomiting or abdominal pain.

Pooled data showed an overall CWS rate of 47%. But population-based studies yielded a prevalence of 17%, while data from participants in outpatient clinics revealed a rate of 54% and data from participants in inpatient samples yielded a prevalence of 87%. A higher prevalence of CWS was found in those who concurrently used cannabis with tobacco and other substances of abuse.

Despite the fact that cannabis withdrawal syndrome hasn't been completely accepted, it's good to collate what's out there, said Dr. Michael Lynch, medical director of the Pittsburgh Poison Center at UPMC and an assistant professor of medical toxicology in the department of emergency medicine at the University of Pittsburgh School of Medicine.

"It's helpful to go through the data in a systematic way with a meta-analysis," Lynch said. "Many of the studies that are out there are either small or not of great quality, so pooling the data may give us a more accurate picture. Having said that, any time you do a meta-analysis with subpar studies the final outcome may not reflect the truth. But it's the best we have."

Lynch was not surprised to see the new numbers, especially for those seeking treatment. People who get admitted to inpatient programs are more likely to have other risk factors that can contribute to a withdrawal syndrome, Lynch said. "Also, those are the people who are more likely to have heavy, significant use as opposed to those who did not need treatment, he added.

It can be difficult to get a handle on a withdrawal syndrome that doesn't have physical indicators, Lynch said. "I think it's a real phenomenon -- people definitely feel worse when they stop," he added. "What the mechanism is and if there is a truly chemical withdrawal is hard to know."

SOURCE: JAMA Network Open, online April 9, 2020.