U.S. Surgeon General’s Advisory: Marijuana Use and the Developing Brain

Background • Use in Pregnancy • Use in Adolescence • Info for Parents • Info for Health Professionals

I, Surgeon General VADM Jerome Adams, am emphasizing the importance of protecting our Nation from the health risks of marijuana use in adolescence and during pregnancy. Recent increases in access to marijuana and in its potency, along with misperceptions of safety of marijuana endanger our most precious resource, our nation’s youth.

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Background

Marijuana, or cannabis, is the most commonly used illicit drug in the United States. It acts by binding to cannabinoid receptors in the brain to produce a variety of effects, including euphoria, intoxication, and memory and motor impairments. These same cannabinoid receptors are also critical for brain development. They are part of the endocannabinoid system, which impacts the formation of brain circuits important for decision making, mood and responding to stressBrents L. K. (2016). Marijuana, the Endocannabinoid System and the Female Reproductive System. The Yale journal of biology and medicine, 89(2), 175–191..

Marijuana and its related products are widely available in multiple forms. These products can be eaten, drunk, smoked, and vapedNational Center for Chronic Disease Prevention and Health Promotions, Centers for Disease Control and Prevention. Marijuana and Public Health: How is marijuana used? https://www.cdc.gov/marijuana/faqs/how-is-marijuana-used.html.. Marijuana contains varying levels of delta-9-tetrahydrocannabinol (THC), the component responsible for euphoria and intoxication, and cannabidiol (CBD). While CBD is not intoxicating and does not lead to addiction, its long-term effects are largely unknown, and most CBD products are untested and of uncertain purityBonn-Miller M.O., Loflin M.J.E., Thomas B.F, et al. Labeling Accuracy of Cannabidiol Extracts Sold Online. JAMA. 2017;318(17):1708-1709. doi:10.1001/jama.2017.11909..

Marijuana has changed over time. The marijuana available today is much stronger than previous versions. The THC concentration in commonly cultivated marijuana plants has increased three-fold between 1995 and 2014 (4% and 12% respectively)Elsohly, M. A., Mehmedic, Z., Foster, S. (2016). Changes in Cannabis Potency Over the Last 2 Decades (1995-2014): Analysis of Current Data in the United States. Biological Psychiatry, 79(7), 613-619. doi:10.1016/j.biopsych.2016.01.004.. Marijuana available in dispensaries in some states has average concentrations of THC between 17.7% and 23.2%Jikomes, N., & Zoorob, M. (2018). The Cannabinoid Content of Legal Cannabis in Washington State Varies Systematically Across Testing Facilities and Popular Consumer Products. Scientific reports, 8(1), 4519. doi:10.1038/s41598-018-22755-2. Concentrated products, commonly known as dabs or waxes, are far more widely available to recreational users today and may contain between 23.7% and 75.9% THCAlzghari, S. K., Fung, V., Rickner, S. S., Chacko, L., & Fleming, S. W. (2017). To Dab or Not to Dab: Rising Concerns Regarding the Toxicity of Cannabis Concentrates. Cureus, 9(9), e1676. doi:10.7759/cureus.1676..

The risks of physical dependence, addiction, and other negative consequences increase with exposure to high concentrations of THCFreeman, T. P., & Winstock, A. R. (2015). Examining the profile of high-potency cannabis and its association with severity of cannabis dependence. Psychological medicine, 45(15), 3181–3189. doi:10.1017/S0033291715001178 and the younger the age of initiation. Higher doses of THC are more likely to produce anxiety, agitation, paranoia, and psychosisVolkow N.D., Baler R.D., Compton W.M., Weiss S.R.B. Adverse Health Effects of Marijuana Use N Engl J Med. 2014 June 5; 370(23): 2219–2227. doi:10.1056/NEJMra1402309.. Edible marijuana takes time to absorb and to produce its effects, increasing the risk of unintentional overdose, as well as accidental ingestion by childrenRichards, J.R., Smith N.E., Moulin, A.K. Unintentional Cannabis Ingestion in Children: A Systematic Review. J Pediatr 2017; 190:142-52. and adolescentsCao, D., Sahaphume, S., Bronstein, A.C., Hoyte, C.O., Characterization of edible marijuana product exposures reported to the United States poison centers. Clinical Toxicology, 54:9, 840-846, DOI: 10.1080/15563650.2016.1209761. In addition, chronic users of marijuana with a high THC content are at risk for developing a condition known as cannabinoid hyperemesis syndrome, which is marked by severe cycles of nausea and vomitingGalli, J.A., Sawaya, R.A., Friedenberg, F.K. Cannabinoid Hyperemesis Syndrome. Curr Drug Abuse Rev. 2011 Dec; 4(4): 241–249..

This advisory is intended to raise awareness of the known and potential harms to developing brains, posed by the increasing availability of highly potent marijuana in multiple, concentrated forms. These harms are costly to individuals and to our society, impacting mental health and educational achievement and raising the risks of addiction and misuse of other substances.  Additionally, marijuana use remains illegal for youth under state law in all states; normalization of its use raises the potential for criminal consequences in this population. In addition to the health risks posed by marijuana use, sale or possession of marijuana remains illegal under federal law notwithstanding some state laws to the contrary.

Watch the Surgeon General Answer FAQs on Marijuana

Video: Answering Your Marijuana Questions

The U.S. Surgeon General addresses marijuana-related questions he often receives including those related to the chemical composition and potency of today’s marijuana, associated risks, and what parents and teachers can say to young people about marijuana.

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Marijuana Use during Pregnancy

Pregnant women use marijuana more than any other illicit drug. In a national survey, marijuana use in the past month among pregnant women doubled (3.4% to 7%) between 2002 and 2017Volkow N.D., Han B., Compton W.M., McCance-Katz E.F. Self-reported Medical and Non-medical Cannabis Use Among Pregnant Women in the United States. JAMA. 2019 doi:10.1001/jama.2019.7982. In a study conducted in a large health system, marijuana use rose by 69% (4.2% to 7.1%) between 2009 and 2016 among pregnant womenYoung-Wolff KC, Tucker L, Alexeeff S, et al. Trends in Self-reported and Biochemically Tested Marijuana Use Among Pregnant Females in California From 2009-2016. JAMA. 2017;318(24):2490–2491. doi:10.1001/jama.2017.17225.. Alarmingly, many retail dispensaries recommend marijuana to pregnant women for morning sicknessDickson, B. (2018). Recommendations From Cannabis Dispensaries About First-Trimester Cannabis Use. Obstetrics & Gynecology. 2018; 0029-7844. doi:10.1097/AOG.0000000000002619..

Marijuana use during pregnancy can affect the developing fetus.

  • THC can enter the fetal brain from the mother’s bloodstream.
  • It may disrupt the endocannabinoid system, which is important for a healthy pregnancy and fetal brain developmentBrents L. K. (2016). Marijuana, the Endocannabinoid System and the Female Reproductive System. The Yale journal of biology and medicine, 89(2), 175–191.
  • Studies have shown that marijuana use in pregnancy is associated with adverse outcomes, including lower birth weightNational Academies of Sciences, Engineering, and Medicine. 2017. The health effects of cannabis and cannabinoids: Current state of evidence and recommendations for research. Washington, DC: The National Academies Press..
  • The Colorado Pregnancy Risk Assessment Monitoring System reported that maternal marijuana use was associated with a 50% increased risk of low birth weight regardless of maternal age, race, ethnicity, education, and tobacco useCrume et al: Cannabis use during the perinatal period in a state with legalized recreational and medical marijuana: the association between maternal characteristics, breastfeeding patterns, and neonatal outcomes. J Pediatr. 2018;197:90-96..

The American College of Obstetricians and Gynecologists holds that “[w]omen who are pregnant or contemplating pregnancy should be encouraged to discontinue marijuana use. Women reporting marijuana use should be counseled about concerns regarding potential adverse health consequences of continued use during pregnancy”American College of Obstetricians and Gynecologists: Marijuana use during pregnancy and lactation. Committee Opinion No. 722. Obstet Gynecol. 2017;130(4):e205-e209.. In 2018, the American Academy of Pediatrics recommended that “…it is important to advise all adolescents and young women that if they become pregnant, marijuana should not be used during pregnancy”Ryan et al: Marijuana use during pregnancy and breastfeeding: implications for neonatal and childhood outcomes. Pediatrics. 2018; 142(3):,e20181889..

Maternal marijuana use may still be dangerous to the baby after birth. THC has been found in breast milk for up to six days after the last recorded use. It may affect the newborn’s brain development and result in hyperactivity, poor cognitive function, and other long-term consequencesBertrand, K. A., Hanan, N. J., Honerkamp-Smith, G., Best, B. M., & Chambers, C. D. (2018). Marijuana Use by Breastfeeding Mothers and Cannabinoid Concentrations in Breast Milk. Pediatrics, 142(3). doi:10.1542/peds.2018-1076., Metz TD, Stickrath EH: Marijuana use in pregnancy and lactation: a review of the evidence. Am J Obstet Gynecol. 2015;213(6):761-778., Effects while pregnant or breastfeeding. (2017, March 02). Retrieved from https://www.colorado.gov/pacific/marijuana/effects-while-pregnant-or-breastfeeding.. Additionally, marijuana smoke contains many of the same harmful components as tobacco smokeMoir, D., et al., A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two machine smoking conditions. Chem Res Toxicol 21: 494-502. (2008).. No one should smoke marijuana or tobacco around a baby.

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Marijuana Use during Adolescence

Marijuana is also commonly used by adolescents4, second only to alcohol. In 2017, approximately 9.2 million youth aged 12 to 25 reported marijuana use in the past month and 29% more young adults aged 18-25 started using marijuanaSubstance Abuse and Mental Health Services Administration. (2018). Key Substance Use and Mental Health Indicators in the United States: Results from the 2017 National Survey on Drug Use and Health (HHS Publication No. SMA 18-5068, NSDUH Series H-53). Rockville, MD: Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration. In addition, high school students’ perception of the harm from regular marijuana use has been steadily declining over the last decadeJohnston, L. D., Miech, R. A., O'Malley, P. M., Bachman, J. G., Schulenberg, J. E., & Patrick, M. E. (2019). Monitoring the Future national survey results on drug use, 1975-2018: Overview, key findings on adolescent drug use. Ann Arbor: Institute for Social Research, The University of Michigan, 119 pp.. During this same period, a number of states have legalized adult use of marijuana for medicinal or recreational purposes, while it remains illegal under federal law. The legalization movement may be impacting youth perception of harm from marijuana. 

The human brain continues to develop from before birth into the mid-20s and is vulnerable to the effects of addictive substancesPujol, J., Vendrell, P., Junqué, C., Martí-Vilalta, J. L., & Capdevila, A. (1993). When does human brain development end? Evidence of corpus callosum growth up to adulthood. Annals of Neurology, 34(1), 71-75. doi:10.1002/ana.410340113., Levine, A., Clemenza, K., Rynn, M., & Lieberman, J. (2017). Evidence for the Risks and Consequences of Adolescent Cannabis Exposure. Journal of the American Academy of Child & Adolescent Psychiatry, 56(3), 214-225. doi:10.1016/j.jaac.2016.12.014.. Frequent marijuana use during adolescence is associated with:

  • Changes in the areas of the brain involved in attention, memory, decision-making, and motivation. Deficits in attention and memory have been detected in marijuana-using teens even after a month of abstinenceMeruelo AD, Castro N, Cota CI, Tapert SF. Cannabis and alcohol use, and the developing brain. Behav Brain Res. 2017;325(Pt A):44–50. doi:10.1016/j.bbr.2017.02.025..
  • Impaired learning in adolescents. Chronic use is linked to declines in IQ, school performance that jeopardizes professional and social achievements, and life satisfactionMeier M.H., Caspi A., Ambler A., et. al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci USA., 2012. Oct 2; 109(40) E2657-64 doi 10.1073/pnas. 1206820109. Epub 2012 Aug 27.
  • Increased rates of school absence and drop-out, as well as suicide attemptsSilins, E., Horwood, L. J., & Patton, G. C. (2014). Young adult sequelae of adolescent cannabis use: An integrative analysis. The Lancet Psychiatry, 1(4), 286-293. doi:10.1016/s2215-0366(14)70307-4..

Risk for and early onset of psychotic disorders, such as schizophrenia. The risk for psychotic disorders increases with frequency of use, potency of the marijuana product, and as the age at first use decreasesDi Forti, M., Quattrone, D., & Freeman, T. (2019). The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): A multicenter case-control study. The Lancet Psychiatry, 6(5), 427-436. doi:10.1016/S2215-0366(19)30048-3.. 

  • Other substance useLopez-Quintero C., Perez de los Cabos J., Hasin D.S. (2011). Probability and predictors of transition from first use to dependence on nicotine, alcohol, cannabis, and cocaine: results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug Alcohol Dependence. 115(1-2):120-130., Jones, C. M., & McCance-Katz, E.F. (2019). Relationship Between Recency and Frequency of Youth Cannabis Use on Other Substance Use. Journal of Adolescent Health, 64(3), 411-413. doi:10.1016/j.jadohealth.2018.09.017.. In 2017, teens 12-17 reporting frequent use of marijuana showed a 130% greater likelihood of misusing opioids23.

Marijuana’s increasingly widespread availability in multiple and highly potent forms, coupled with a false and dangerous perception of safety among youth, merits a nationwide call to action. 

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You Can Take Action

No amount of marijuana use during pregnancy or adolescence is known to be safe. Until and unless more is known about the long-term impact, the safest choice for pregnant women and adolescents is not to use marijuana.  Pregnant women and youth--and those who love them--need the facts and resources to support healthy decisions. It is critical to educate women and youth, as well as family members, school officials, state and local leaders, and health professionals, about the risks of marijuana, particularly as more states contemplate legalization.

Science-based messaging campaigns and targeted prevention programming are urgently needed to ensure that risks are clearly communicated and amplified by local, state, and national organizations. Clinicians can help by asking about marijuana use, informing mothers-to-be, new mothers, young people, and those vulnerable to psychotic disorders, of the risks. Clinicians can also prescribe safe, effective, and FDA-approved treatments for nausea, depression, and pain during pregnancy. Further research is needed to understand all the impacts of THC on the developing brain, but we know enough now to warrant concern and action. Everyone has a role in protecting our young people from the risks of marijuana.

Information for Parents and Parents-to-be

You have an important role to play for a healthy next generation.

Information for Youth:

You have an important role to play for a healthy next generation.

Information for States, Communities, Tribes, and Territories:

You have an important role to play for a healthy next generation.

Information for Health Professionals:

You have an important role to play for a healthy next generation.

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