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Cannabis and Brain Health

Key points

  • Cannabis affects brain development.
  • Cannabis use directly affects brain function — specifically the parts of the brain responsible for memory, learning, attention, decision-making, coordination, emotions, and reaction time.

Short and long-term effects of cannabis use on the brain

What are the short-term effects of cannabis use on the brain?

Recent cannabis use (defined as within 24 hours) in youth and adults has an immediate impact on thinking, attention, memory, coordination, movement, and time perception.1

What are the long-term effects of cannabis use on the brain?

Cannabis affects brain development. Developing brains, such as those in babies, children, and teenagers, are especially susceptible to the harmful effects of cannabis and tetrahydrocannabinol (THC) because the brain is continuing to develop until around age 25.12 Although scientists are still learning about the effects of cannabis on developing brains, studies suggest that cannabis use by mothers during pregnancy could be linked to problems with attention, memory, problem-solving skills, and behavior in their children.345678

Using cannabis before age 18 may affect how the brain builds connections for functions like attention, memory, and learning.9 Cannabis's effects on attention, memory, and learning may last a long time or even be permanent,10 but more research is needed to fully understand these effects.

Youth who use cannabis may not do as well in school and may have trouble remembering things.1611

Factors that determine impact

The impact of cannabis use on the brain depends on many factors, including:

  • Amount of tetrahydrocannabinol (THC) in cannabis (in other words, the concentration or strength),
  • How often it is used,
  • Age of first use, and
  • Whether other substances (for example, tobacco and alcohol) are used at the same time.

Long-term impacts on the brain may also be caused by something other than cannabis, such as genetics, the home environment, or other unknown factors.12 The National Institute on Drug Abuse is conducting a large long-term study (the Adolescent Brain Cognitive Development study, or ABCD study) to better understand the role cannabis and other substances play in adolescent brain development.

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National Center for Injury Prevention and Control
  1. National Academies of Sciences, Engineering, and Medicine. The health effects of cannabis and cannabinoids: the current state of evidence and recommendations for research. Washington, DC: The National Academies Press; 2017. https://nap.nationalacademies.org/catalog/24625/the-health-effects-of-cannabis-and-cannabinoids-the-current-state. Accessed February 8, 2024.
  2. Giedd JN. The teen brain: Insights from neuroimaging. J Adolesc Health. 2008;42(4):335–343. doi: 10.1016/j.jadohealth.2008.01.007.
  3. Grewen K, Salzwedel AP, Gao W. Functional Connectivity Disruption in Neonates with Prenatal Marijuana Exposure. Front Hum Neurosci. 2015;9:601. doi: 10.3389/fnhum.2015.00601.
  4. Goldschmidt L, Day NL, Richardson GA. Effects of prenatal marijuana exposure on child behavior problems at age 10. Neurotoxicol Teratol. 2000;22(3):325-336. doi: 10.1016/s0892-0362(00)00066-0.
  5. Leech S, Richardson GA, Goldschmidt L, et al. Prenatal substance exposure: effects on attention and impulsivity of 6-year-olds. Neurotoxicol Teratol. 1999;21(2):109-118. doi: 10.1016/s0892-0362(98)00042-7.
  6. Fried PA, Watkinson B, Gray R. Differential effects on cognitive functioning in 9-to 12-year olds prenatally exposed to cigarettes and marihuana. Neurotoxicol Teratol. 1998;20(3):293-306. doi: 10.1016/s0892-0362(97)00091-3.
  7. El Marroun H, Hudziak JJ, Tiemeier H, et al. Intrauterine cannabis exposure leads to more aggressive behavior and attention problems in 18-month-old girls. Drug Alcohol Depend. 2011;118(2-3):470-474. doi: 10.1016/j.drugalcdep.2011.03.004.
  8. Ryan SA, Ammerman SD, O'Connor ME. Marijuana use during pregnancy and breastfeeding: implications for neonatal and childhood outcomes. Pediatrics. 2018;142(3):e20181889. doi: 10.1542/peds.2018-1889.
  9. Department of Health and Human Services. National Institutes of Health. National Institute on Drug Abuse. https://www.drugabuse.gov/drug-topics/marijuana. Accessed February 9, 2024.
  10. Meier MH, Caspi A, Ambler A, et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci USA. 2012;109(40):E2657-E2664. doi: 10.1073/pnas.1206820109.
  11. Filbey FM, Aslan S, Calhoun VD, et al. Long-term effects of marijuana use on the brain. Proc Natl Acad Sci USA. 2014;111(47):16913-16918. doi: 10.1073/pnas.1415297111.
  12. Jackson NJ, Isen JD, Khoddam R, et al. Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies. Proc Natl Acad Sci USA. 2016;113(5):E500-E508. doi: 10.1073/pnas.1516648113.
  • Jackson NJ, Isen JD, Khoddam R, et al. Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies. Proceedings of the National Academy of Sciences. 2016;113(5):E500-E508.