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Jerry Overman, PharmD, BCPP
Program Committee Administrative Chair

This session can be purchased in CPNP University.

As marijuana has become easier to obtain secondary to its legal status for both recreational and medical purposes in many states, there has been growing concern about the effect its use has on the developing brains of children and adolescents, who may more easily obtain it through illegal means. Dr. Susan Tapert, Professor and Associate Vice Chair of Academic Affairs at the UC San Diego Department of Psychiatry gave an informative keynote address at the 2017 Annual CPNP Meeting, reviewing the rates of marijuana use and marijuana use disorders in the adolescent population, describing the brain structure and function affected by the illicit use of marijuana among adolescents, summarizing the negative outcomes of marijuana use including poor cognition, behavior, academic and social functioning and explaining why the adolescent population still developing neural connections, is particularly susceptible to poor long term outcomes. Finally, she helped design a plan for the psychiatric pharmacist’s role in the education and treatment of marijuana use disorders and how better to identify and comprehensively manage teens using marijuana.

Dr. Tapert is Scientific Director and a site PI for the National Consortium on Alcohol and NeuroDevelopment in Adolescence (NCANDA), and Associate Director and a site PI for the Adolescent Brain Cognitive Development (ABCD) study, which launched in 2015 to study brain and cognitive development of over 10,000 children spanning 10 years. Her research focuses on understanding neural sequelae of and risk factors for adolescents substance use. Her work utilizes a range of techniques, including magnetic resonance imaging (MRI), functional MRI, diffusion tensor imaging, and neuropsychological testing.

Cannabinoid receptors are widely distributed throughout the brain (e.g., hippocampus, prefrontal cortex, and cerebellum) and play an important role in neurotransmitter release across neural systems. It has been suggested that these receptors increase during adolescence, have a role in genetic expression of neural development, and that alteration of the endocannabinoid system during adolescence may result in a cascade of neurochemical and neurostructural aberrations leading to poorer cognition and emotional outcomes in adulthood. With the prevalence of cannabis use in youth, concerns have been raised as to the long term effects of cannabinoids on brain development and function. The keynote address was very informative, helping to educate the pharmacist dealing with these important issues of neurodevelopment by reviewing the literature to date related to marijuana use in adolescents and discussing the deleterious effects marijuana may have on the development of the adolescent brain. 

Dr. Tapert opened her lecture describing the many forms by which marijuana can be ingested, be it the traditional joint, bowl or bong, edibles including brownies and candies with ‘standard‘ serving sizes, hash and it’s concentrates and the synthetic cannabinoids, such as spice and K2. After addressing usage rates and trajectories, based on age, she described the increase in the potency marijuana over the last 8 to 10 years and its pharmacologic effect in the cortex and hippocampus. Gray and white matter development was described in the developing brain, followed by the effect of marijuana and alcohol on this important neural development.

The cognitive effects of marijuana usage, possible the most concerning during the development due to its effect on school and social functioning, was a very interesting part of the discussion. Particularly, attention, memory and spatial functioning appear to be the most affected. Some of the specific areas of the brain most affected include the left and right superior parietal cortex, the right paracentral gyrus, and the left pericalcarine. Clinical characteristics were described, as well as appropriate treatment options including motivational enhancement therapy (MET) and cognitive behavioral therapy (CBT). It was made clear throughout Dr. Tapert’s lecture that the risks of usage during adolescence clearly outweigh any possible benefits during typical adolescent development. The need for large, prospective studies in this population was also highlighted. 

References

  1. Paula CB, McQueeny T, Lisdahl KM, Price JS, Talpert SF. Craving associated with amygdala volumes in adolescent marijuana users during abstinence. Am J Drug Alcohol Abuse. 2015;41(2):127-32.
  2. Jacobus J, Squeglia LM, Meruelo AD, Castro N, Brumback T, Giedd JN, et al. Cortical thickness in adolescent marijuana and alcohol users: A three-year prospective study from adolescence to young adulthood. Dev Cognitive Neurosci. 2015;16:101- 109. DOI: 10.1016/j.dcn.2015.04.006.
  3. Jacobus J, Tapert S. Effects of Cannabis on the Adolescent Brain. CPD. 2014;20(13):2186- 2193. DOI: 10.2174/13816128113199990426.
  4. Volkow ND, Baler RD, Compton WM, Weiss SRB. Adverse health effects of marijuana use. N Engl J Med. 2014;370(23):2219-27. DOI: 10.1056/NEJMra1402309. PubMed PMID: 24897085.
  5. Meier MH, Caspi A, Ambler A, Harrington H, Houts R, Keefe RSE, et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci. 2012;109(40):E2657-64. DOI: 10.1073/pnas.1206820109. PubMed PMID: 22927402; PubMed Central PMCID: PMC3479587.
  6. Lisdahl KM, Wright NE, Medina-Kirchner C, Maple KE, Shollenbarger S. Considering Cannabis: The Effects of Regular Cannabis Use on Neurocognition in Adolescents and Young Adults. Curr Addict Rep. 2014:1(2):144-156. DOI: 10.1007/s40429-014-0019-6.
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