Marijuana and …

School and Sports

Marijuana affects perception, judgment and memory (1). The drug can make you a wreck in school, in sports or clubs, or with your friends. If you’re high on, you are more likely to make mistakes that could embarrass or even hurt you. If you use marijuana a lot, you may start to lose interest in how you look and how you’re getting along at school.

Athletes may find their performance is off; timing, movements, and coordination are all affected by marijuana. Also, since it can affect judgment and decision-making, using marijuana can lead to risky sexual behavior, resulting in exposure to sexually transmitted diseases like HIV, the virus that causes AIDS.


Marijuana has serious harmful effects on the skills required to drive safely: alertness, concentration, coordination, and reaction time. Using it may make it difficult to judge distances and react to sounds and signals on the road.

Marijuana can play a role in car accidents. In one study conducted in Memphis, TN, researchers found that, of 150 reckless drivers who were tested for drugs at the arrest scene, 33 percent tested positive for marijuana, and 12 percent tested positive for both marijuana and cocaine (2). Data have also shown that while smoking marijuana, people show the same lack of coordination on standard “drunk driver” tests as do people who have had too much to drink (3).


Doctors advise pregnant women not to use any drugs because harm may come to the growing fetus. Although one animal study has linked marijuana use to loss of the fetus very early in pregnancy, two studies in humans found no association between marijuana use and early pregnancy loss. More research is necessary to fully understand the effects of marijuana use on pregnancy outcome.  Nonetheless, it is advisable not to start.

Studies in children born to mothers who used marijuana have shown increased behavioral problems during infancy and preschool years. In school, these children are more likely to have problems with decision-making, memory, and the ability to remain attentive (4).

Researchers are not certain whether health problems that may be caused by early exposure to marijuana will remain as the child grows into adulthood. However, since some parts of the brain continue to develop throughout adolescence, it is also possible that certain kinds of problems may appear as the child matures.

References include The National Institute on Drug Abuse and:

1  Pope, H. G. and Yurgelun-Todd, D. The Residual Cognitive Effects of Heavy Marijuana Use in College Students. Journal of the American Medical Association, Vol 275, No. 7, February 21, 1996.

2  Brookoff, D.; Cook, C. S.; Williams, C.; and Mann, C. S. Testing reckless drivers for cocaine and marijuana. New England Journal of Medicine, 331:518-522, 1994.

3 Liguori, A.; Gatto, C. P.; and Robinson, J. H. Effects of marijuana on equilibrium. psychomotor performance, and simulated driving. Behavioral Pharmacology, 9:599-609, 1998.

4 Cornelius, M. D.; Taylor, P. M.; Geva, D.; and Day, N. L. Prenatal tobacco and marijuana use among adolescents: effects on offspring gestational age, growth, and morphology. Pediatrics, 95: 738-743. 1995.