March 30, 2016

What Do We Tell Patients About Marijuana?

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Paul King, MD, and Marc King, LMSW

Parkwood Behavioral Health System, Olive Branch, Mississippi (Dr King), and Mid-South Health Systems, West Memphis, Arkansas (Mr King)


In 23 states, medical use of marijuana is legal. Cannabis or marijuana refers to the plant cannabis sativa or cannabis indica, containing the psychoactive chemical delta-9-tetrahydrocannabinol or THC. In a meta-analysis of 79 trials involving 6,462 participants, the authors concluded that “moderate-quality evidence” supports the use of cannabinoids in chronic pain and spasticity, but they are associated with short-term adverse events.

One small retrospective study showed that marijuana improved the symptoms of PTSD according to scores on the Clinician Administered Posttraumatic Scale for DSM-IV (CAPS), but the authors stated that prospective, placebo-controlled studies were needed. A prospective study of 2,276 veterans showed that marijuana use was statistically significantly associated with a worse outcome in PTSD severity. Additionally, there was a higher incidence of violent behavior in the group using marijuana after discharge. The authors concluded, “Marijuana may actually worsen PTSD symptoms or nullify the effects of specialized, intensive treatment.”

In 2016, premium grade marijuana is more easily available than ever before. The marijuana available today appears to be more potent (ie, have greater THC content) than the marijuana of past decades. This greater potency results in not only an increase in euphoria but also increased adverse effects: short-term memory problems, motor incoordination, and psychotic reactions. Improved delivery systems such as “vaping” and “dabbing” only increase the risks. Liquid forms of marijuana can be placed in modified electronic smoking devices. When hash oil is vaporized, a highly concentrated THC is created. The use of a modified vaporizer pen effectively hides the telltale marijuana odor.

Whether or not marijuana has medicinal properties remains unclear. An interesting and provocative psychiatric question is, Does marijuana increase the risk for schizophrenia? An expert roundtable discussed this question for the CME Institute. The evidence pointed to an increased risk for psychosis among early, frequent users of cannabis, especially of a high-potency variety. Unfortunately, as Alan I. Greene, MD, stated, “The term medical marijuana makes it sound like a therapeutic agent, which may encourage more young people to use it.” Data from 2013–2014 indicated that about 7% of US youth aged 12 to 17 years used marijuana in the past month. Among full-time college students, data from 2002–2013 showed an average of about 1,000 new marijuana users per day.

Patients may self-titrate the drug because the general public perceives marijuana to be safe. Young people need a “clear head” in order to safely drive a vehicle, perform in school, and hold down a job without excessive absenteeism. It is up to the mental health professional to advise our patients or clients based on the clinical evidence.

Financial disclosure:Dr King and Mr King had no relevant personal financial relationships to report. ​

Category: Medical Conditions , Psychosis , PTSD , Schizophrenia , Substance Use Disorder
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One thought on “What Do We Tell Patients About Marijuana?

  1. -The National Institute of Health US warns of a doubling of the use of marijuana and similarly increased marijuana addiction 2002- 2012. (Reference 1)
    -The National Institute of Medicine of the United States clarifies that purified cannabinoids are not cannabis (marihuana) and raw and smoked marijuana should not be classified as a medicine. Cannabinoids are not marijuana and some are studied in experimental protocols to assess their potential medical uses.
    “If there is any future for marijuana as medicine is in its isolated components, the cannabinoids and their synthetic derivatives. Isolated cannabinoids provide more reliable effects than mixtures of raw vegetables. Therefore, the purpose of clinical trials smoked marijuana would not be to develop marijuana as a licensed drug but rather to serve as a first step towards the development of non smoked cannabinoid and rapid effect. (Reference 2)
    1. .”Prevalence of Marijuana Use Among U.S. Adults Doubles Over Past Decade”;
    National Institute of Health (NIH) ; October 21, 2015.
    2. “Marijuana and medicine: Assessing the science base; Institute of Medicine. Preface ix. In Joy JE, Benson JA, Watson SJ, eds., . Washington, DC: Institute of Medicine, National Academy Press, 1999

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