Heavy Marijuana Use Affects Learning and Social Skills

Strong Link Found to Marijuana and Lowered Intellect Levels

young people smoking marijuana

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Numerous scientific research studies have shown that heavy marijuana use can negatively affect a person's learning abilities and behavior skills. The studies suggest that a person who smokes marijuana every day may be functioning at a somewhat reduced intellectual level even during periods of brief abstinence.

The upside is after several weeks of quitting the drug, in most cases, people who had used marijuana for long periods of time could recover their cognitive abilities. Although, there is some evidence that significant marijuana use in adolescence can lead to subtle but lasting changes in the adult brain.

What the Research Says

The National Institute on Drug Abuse (NIDA) looked at 11 scientific research studies and concluded that heavy marijuana use, which is defined as smoking marijuana 27 days in 30 days, has a significant impact on person's ability to learn, remember what they learned, and function in society.

General Effects of Heavy Marijuana Use

According to the research results, heavy marijuana use revealed a link to several psychiatric and memory problems.

  • The potential link to depression, anxiety, and certain personality disorders.
  • Decrease the ability to learn and remember information, making it more likely to fall behind the norm on developing intellectual, job, and social behaviors.
  • Dampened the ability to remember and learn for days and weeks after abstinence from marijuana use.

Effects of Daily Marijuana Use on Students

Some research has shown that daily marijuana use by students showed problems in focus, scholastic performance, and memory.

  • Students were getting lower grades and becoming less likely to graduate, compared to students who did not use marijuana.
  • Students had significantly impaired skills related to attention, memory and learning even after not using marijuana for 24 hours.
  • Students had problems in sustaining and shifting attention.
  • Students had problems with the ability to register, organize and use information, even compared to occasional users of marijuana.
  • Students had an impaired ability to recall words from a list a week after quitting marijuana use.

Effects on Work Performance

Some findings on heavy marijuana users in the workplace showed problems in absences, tardiness, accidents, and cognitive abilities.

  • People in the workplace who used marijuana were more likely to experience increased absences (75 percent), tardiness, accidents, workers' compensation claims, and job turnover.
  • People in the workplace who tested positive for marijuana use had 55 percent more industrial accidents and 85 percent more injuries compared to non-marijuana users.
  • Heavy marijuana abusers self-report that their use of the drug had negative effects on their cognitive abilities, career status, social life, and physical and mental health.​

Consequences of Early Marijuana Use

A person's brain is still developing up until the early 20s. Experts agree that the later someone begins using marijuana the better.

A Duke University study found that children who smoke marijuana before age 18 displayed lasting harm to their intelligence, attention, and memory compared with those who began using marijuana after age 18.

The study also found that, unlike adults, quitting marijuana use did not entirely reverse the cognitive damaged caused by regular marijuana use.

8 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Pope HG, Yurgelun-Todd D. "The Residual Cognitive Effects of Heavy Marijuana Use in College Students." Journal of the American Medical Association 275(7):521–527, 1996. PMID: 8606472

  2. Rubino T, Parolaro D. Long Lasting Consequences of Cannabis Exposure in Adolescence. Molecular and Cellular Endocrinology. Volume 286, Issues 1–2, Supplement 1, 16 April 2008, Pages S108–S113. DOI: 10.1016/j.mce.2008.02.003

  3. Brook JS, Rosen Z, Brook DW. "The Effect of Early Marijuana Use on Later Anxiety and Depressive Symptoms." NYS Psychologist 35–39, January 2001. doi: 10.1186/1471-244X-14-136

  4. Block RI, Ghoneim MM. "Effects of chronic marijuana use on human cognition." Psychopharmacology 100(1–2):219–228, 1993. DOI: 10.1007/BF02246977

  5. Lynskey M, Hall W. "The Effects of Adolescent Cannabis Use on Educational Attainment: A Review." Addiction 95(11):1621–1630, 2000. PMID: 11219366

  6. Zwerling C, Ryan J, Orav EJ. "The Efficacy of Pre-Employment Drug Screening for Marijuana and Cocaine in Predicting Employment Outcome." Journal of the American Medical Association 264(20):2639–2643, 1990.

  7. Brook JS, Balka EB, Whiteman M. "The Risks for Late Adolescence of Early Adolescent Marijuana Use." American Journal of Public Health 89(10):1549–1554, 1999. PMID: 10511838

  8. Duke University. "Adolescent Pot Use Leaves Lasting Mental Deficits." Duke Today August 2012

Additional Reading

By Buddy T
Buddy T is an anonymous writer and founding member of the Online Al-Anon Outreach Committee with decades of experience writing about alcoholism.