Sep 23, 2020
Richard Balon, MD, returns to the Psychcast, this time to
conduct a Masterclass on the impact of marijuana use on patients,
Dr. Balon is professor of
clinical psychiatry and anesthesiology and associate chair of
education at Wayne State University in Detroit. He has no
- Marijuana remains a controversial topic as potential
legalization looms large in public policy and various groups
espouse the positive benefits of marijuana.
- Current marijuana formulations are more potent than
formulations used in previous years. Formulations used today have a
higher tetrahydrocannabinol content, with up to 80% THC content
achieved through artificial selection.
- Clinicians are rightly concerned about the well-established
negative effects of marijuana on specific populations, particularly
adolescents. They also worry about the effect of marijuana on brain
development, which could affect educational outcomes, and the
significant risk of developing psychosis and/or schizophrenia after
- Newer research on marijuana use is also suggesting other
negative health outcomes, including a potential link between
marijuana use and an increased risk of developing various types of
- Research over the past 20 years has elucidated the negative
effects of marijuana on brain health and development. Marijuana use
undermines cognitive function, including executive function and
educational outcomes. Longitudinal and twin studies show a decline
in the IQ of adolescents who have used marijuana. This is congruent
with other established research and public health guidelines urging
individuals to avoid the use of psychoactive drugs before the brain
finishes maturing at approximately age 25 years.
- In 2016,
Nora D. Volkow, MD, director of the National Institute on Drug
Abuse, and other leading investigators in the field published a
review of the literature discussing the impact of marijuana
cognitive capacity, amotivational syndrome, and the risk of
psychosis. Ample evidence based on neuropsychological testing
demonstrates a negative impact of marijuana on learning and working
memory. Cannabis amotivational syndrome manifests as apathy,
reduced concentration, and an inability to follow routines or
master new material. Evidence demonstrates that long-term heavy
cannabis use is associated with educational underachievement and
- Marijuana use is considered a preventable risk factor for the
development of psychosis and schizophrenia. Any use of marijuana is
estimated to double the risk of schizophrenia, accounting for
8%-14% of cases, and those at greatest risk include adolescents who
start at an early age, engage in heavy use, and use high-potency
- There is limited evidence about the effect of marijuana on
PTSD, and a study using a large Veterans Affairs database suggests
that marijuana may worsen PTSD symptoms and increase the risk of
- A well-established physical outcome of heavy cannabis use is
cannabis hyperemesis, defined as recurrent nausea, vomiting, and
cramping abdominal pain tied to marijuana use.
- The symptoms may improve temporarily by taking a hot shower or
- Though more research is required, low-strength evidence
suggests that regular marijuana use may be associated with
development of testicular germ cell tumors. The association of
marijuana use with lung and oral cancer is unclear, partly because
marijuana smokers often also smoke cigarettes.
- Given that we know the smoke in cigarettes is a major risk
factor for heart disease, the same concerns must be investigated
for individuals who smoke only marijuana.
Fischer B et al. Am
J Public Health. 2017 Jul 12;107(8):e1-12.
Volkow ND et al.
JAMA Psychiatry. 2016;73(3):292-7.
Lorenzetti V et al.
Eur Neuropsychopharmacol. 2020 Jul;36:169-80.
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Meier MH et al. Addiction.
McAlaney J et al. Eur Addict Res.
2020 May 6;1-8.
Ben Amar M, Potvin S.
J Psychoactive Drugs. 2007;39:131-42.
Wilkinson ST et al. J Clin
Psychiatry. 2015 Sep;76(9):1174-80.
Steenkamp MM et al. Depress
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Chocron Y et al. BMJ. 2019;366:l4336.
Ghasemiesfe M et al.
JAMA Netw Open. 2019;2(11):e1916318.
Show notes by Jacqueline Posada, MD, who is associate producer
of the Psychcast and consultation-liaison psychiatry fellow with
the Inova Fairfax Hospital/George Washington University program in
Falls Church, Va. Dr. Posada has no conflicts of interest.
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