Marijuana Legislation Protects Children

American College of Pediatricians – August 2013

ABSTRACT: Federal Law currently prohibits the manufacture, sale, and distribution of controlled substances such as marijuana. However, despite more than 70 years of well-reasoned restriction of marijuana use in the United States and persistent problems of abuse, there are increased efforts to achieve legalization of marijuana. Medical use of marijuana has prompted many states to establish programs for sale of medically-prescribed marijuana.  Some states have legalized recreational use of marijuana supported by voter-approved referenda.  Others have suggested “decriminalization” of marijuana instead, but this shift in terminology offers little difference in the end result of encouraging free and ready access to marijuana for recreational purposes. Supporters of legalization have become increasingly vigorous in openly campaigning for public acceptance, often citing the high incidence of marijuana use among teenagers. However, even limited legalization in some states has led to a worsening of these rates. Research documents that the risks associated with chronic use of marijuana in adolescents are grave. The American College of Pediatricians advocates policies that are best for children. Therefore, the College supports legislation that continues to prohibit the sale and/or medical use of marijuana.

How Widespread is Marijuana Abuse?

Marijuana is the most commonly used illicit drug in the United States1, 2. In 2011, 22.5 million Americans age 12 and older were current illicit drug users, meaning that they had used an illicit drug during the month prior to the survey interview. Source: National Survey on Drug Use and Health (Substance Abuse and Mental Health Administration website). The NIDA-funded 2010 Monitoring the Future study showed that 13.7 percent of 8th graders, 27.5 percent of 10th graders, and 34.8 percent of 12th graders had abused marijuana at least once in the year prior to being surveyed. After a period of decline in the last decade, its use has generally increased among young people since 2007, corresponding to a diminishing perception of the drug’s risks. The number of users increased from 14.5 million to 18.1 million. According to annual survey data, more teenagers are now current (past-month) smokers of marijuana than of cigarettes. Marijuana is the leading substance mentioned in adolescent emergency room admissions and autopsy reports and is believed to be one of the major contributing factors to violent deaths and accidents among adolescents; it has been reported to be involved in as many as 30 percent of adolescent motor vehicle crashes, 20 percent of adolescent homicides, 13 percent of adolescent suicides, and 10 percent of other unintentional injuries among adolescents.3

Such data indicates an increasing prevalence of marijuana abuse in children and adolescents. Given the widespread use of marijuana, its use for what are purported to be medicinal indications, and the increasing abuse of and dependence on this substance, it is important to examine the adverse clinical consequences.

How is Marijuana Abused?

Marijuana is usually smoked in hand-rolled cigarettes (joints) or in pipes or water pipes (bongs). It is also smoked in blunts—cigars that have been emptied of tobacco and refilled with a mixture of marijuana and tobacco. Marijuana smoke has a pungent and distinctive, usually sweet-and-sour, odor. Marijuana can also be mixed in food or brewed as a tea. Harmful effects of smoking synthetic marijuana have also been reported.

How Does Marijuana Affect the Brain?

The main active chemical in marijuana is THC (delta-9-tetrahydrocannabinol). Short-term effects of marijuana use include problems with memory and learning; distorted perception; difficulty in thinking and problem solving; loss of coordination; and increased heart rate, anxiety, and panic attacks.

When marijuana is smoked, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to the brain and other organs throughout the body. It is absorbed more slowly when ingested in food or drink. (

However it enters the body, THC acts upon specific molecular targets on brain cells, called cannabinoid receptors. These receptors are ordinarily activated by chemicals similar to THC called endocannabinoids, such as anandamide. These receptors are naturally occurring in the body and are part of a neural communication network (the endocannabinoid system) that plays an important role in normal brain development and function. The highest density of cannabinoid receptors is found in parts of the brain that influence pleasure, memory, thinking, concentration, sensory and time perception, and coordinated movement. Marijuana overactivates the endocannabinoid system, causing the high and other effects that users experience. These include distorted perceptions, impaired coordination, difficulty with thinking and problem solving, and disrupted learning and memory. THC affects nerve cells in the region of the brain where memories are formed. This makes it difficult for the user to recall recent events. Chronic exposure to THC may hasten the age-related loss of nerve cells. Marijuana impairs a person’s judgment, coordination, balance, ability to pay attention and reaction time.4 It is known that cannabis induces psychotic symptoms and cognitive impairment in some individuals. Numerous mechanisms have been postulated to link cannabis use, attentional deficits, psychotic symptoms, and neural desynchronization.5

Researchers have found that THC changes the way in which sensory information gets into and is acted on by the hippocampus. This is a component of the brain’s limbic system that is crucial for learning, memory, and the integration of sensory experiences with emotions and motivations. Investigations have shown that THC suppresses neurons in the information-processing system of the hippocampus. In addition, researchers have discovered that learned behaviors, which depend on the hippocampus, also deteriorate.6

Effects on Activities of Daily Living

Research clearly demonstrates that marijuana has the potential to cause problems in daily life or worsen a person’s existing problems. In fact, heavy marijuana users generally report lower life satisfaction, reduced mental and physical health, relationship problems, and less academic and career success compared to their peers who came from similar backgrounds. For example, marijuana use is associated with a higher likelihood of dropping out of school. Several studies also associate workers’ marijuana smoking with increased absences, tardiness, accidents, workers’ compensation claims, and job turnover.

Research has shown that, in chronic users, marijuana’s adverse impact on learning and memory persists after the acute effects of the drug wear off; when marijuana use begins in adolescence, the effects may persist for many years. Research from different areas is converging on the fact that regular marijuana use by young people can have a long-lasting negative impact on the structure and function of their brains.

A major new study published in 2012 in Proceedings of the National Academy of Sciences (and funded partly by NIDA and other NIH institutes) provides objective evidence that, at least for adolescents, marijuana is harmful to the brain.7

The new research is part of a large-scale study of health and development conducted in New Zealand. Researchers administered IQ tests to over 1,000 individuals at age 13 (born in 1972 and 1973) and assessed their patterns of cannabis use at several points as they aged. Participants were again IQ tested at age 38, and their two scores were compared as a function of their marijuana use. The results were striking: Participants who used cannabis heavily in their teens and continued through adulthood showed a significant drop in IQ between the ages of 13 and 38—an average of eight points for those who met criteria for cannabis dependence. (For context, a loss of eight IQ points could drop a person of average intelligence into the lowest third of the intelligence range.) Those who started using marijuana regularly or heavily after age 18 showed minor declines. By comparison, those who never used marijuana showed no declines in IQ.

Other studies have shown a link between prolonged marijuana use and cognitive or neural impairment. A recent report in Brain, for example, reveals neural-connectivity impairment in some brain regions following prolonged cannabis use initiated in adolescence or young adulthood. But the New Zealand study is the first prospective study to test young people before their first use of marijuana and again after long-term use (as much as 20+ years later). Indeed, the ruling out of a pre-existing difference in IQ makes the study particularly valuable. Also, and strikingly, those who used marijuana heavily before age 18 showed mental decline even after they quit taking the drug. This finding is consistent with the notion that drug use during adolescence—when the brain is still rewiring, pruning, and organizing itself—can have negative and long-lasting effects on the brain.

Marijuana and Mental Illness

People who are dependent on marijuana frequently have other comorbid mental disorders (see figure). Population studies reveal an association between cannabis use and increased risk of schizophrenia and, to a lesser extent, depression, and anxiety. There are now sufficient data indicating that marijuana may trigger the onset or relapse of schizophrenia in people predisposed to it, perhaps also intensifying their symptoms.  A number of studies have shown an association between chronic marijuana use and mental illness. High doses of marijuana can produce a temporary psychotic reaction (involving hallucinations and paranoia) in some users, and using marijuana can worsen the course of illness in patients with schizophrenia.8 A series of large prospective studies also showed a link between marijuana use and the later development of psychosis. This relationship was influenced by genetic variables as well as the amount of drug used and the age at which it was first taken—those who start young are at an increased risk for later problems.

Associations have also been found between marijuana use and other mental health problems, such as depression, anxiety, suicidal thoughts among adolescents, and personality disturbances, including a lack of motivation to engage in activities that are typically rewarding. More research is still needed to confirm and better understand these linkages.

Marijuana and Driving

Because it seriously impairs judgment and motor coordination, marijuana also contributes to accidents while driving. A recent analysis of data from several studies found that marijuana use more than doubles a driver’s risk of being in an accident. Further, the combination of marijuana and alcohol is worse than either substance alone with respect to driving impairment.

What Are the Other Health Effects of Marijuana?

Marijuana smoke is an irritant to the lungs, and frequent marijuana smokers can have many of the same respiratory problems experienced by tobacco smokers, such as daily cough and phlegm production, more frequent acute chest illness, and a heightened risk of lung infections. One study found that people who smoke marijuana frequently but do not smoke tobacco have more health problems and miss more days of work than nonsmokers, mainly because of respiratory illnesses.

Marijuana use also has a variety of adverse, short- and long-term effects, especially on cardiopulmonary. Marijuana raises the heart rate by 20-100 percent shortly after smoking; this effect can last up to three hours. In one study, it was estimated that marijuana users have a 4.8-fold increase in the risk of heart attack in the first hour after smoking the drug. This may be due to increased heart rate as well as the effects of marijuana on heart rhythms, causing palpitations and arrhythmias. This risk may be greater in older individuals or in those with cardiac vulnerabilities. Marijuana use has been found to increase blood pressure and heart rate and to decrease the oxygen-carrying capacity of the blood.9
When smoked, marijuana is more harmful than tobacco because it contains more tar and produces increased pathologic (metaplastic) changes.10 Marijuana smokers tend to inhale more deeply and for a longer period of time. It has the same adverse effects on the respiratory system as tobacco smoke and is associated with chronic cough, respiratory infections, bronchitis, emphysema, and lung cancer.11

Chronic smoking of marijuana and its active chemical Ä9-tetrahydrocannabinol (THC) has consistently been shown to increase the risk of developing testicular cancer, in particular a more aggressive form of the disease. THC can cause endocrine disruption resulting in gynecomastia, decreased sperm count, and impotence.12 A study of 369 Seattle-area men aged 18-44 with testicular cancer, and 979 men in the same age bracket without the disease, found that current marijuana users were more likely to develop testicular cancer compared to nonusers.13,14,15 .

Marijuana use during pregnancy is associated with an increased risk of neurobehavioral problems in babies. Because THC and other compounds in marijuana mimic the body’s own cannabinoid-like chemicals, marijuana use by pregnant mothers may alter the developing endocannabinoid system in the brain of the fetus. Consequences for the child may include problems with attention, memory, and problem solving.16

Is Marijuana Medicine?

Although many have called for the legalization of marijuana to treat conditions including pain and nausea caused by HIV/AIDS, cancer, and other conditions, the scientific evidence to date is not sufficient for the marijuana plant to gain FDA approval for two main reasons.

First, there have not been enough clinical trials showing that marijuana’s benefits outweigh its health risks in patients with the symptoms it is meant to treat. The FDA requires carefully conducted studies in large numbers of patients (hundreds to thousands) to accurately assess the benefits and risks of a potential medication.

Also, to be considered a legitimate medicine, a substance must have well-defined and measureable ingredients that are consistent from one unit (such as a pill or injection) to the next. This consistency allows doctors to determine the dose and frequency. As the marijuana plant contains hundreds of chemical compounds that may have different effects and that vary from plant to plant, its use as a medicine is difficult to evaluate.

However, THC-based drugs to treat pain and nausea are already FDA approved and prescribed, and scientists continue to investigate the medicinal properties of cannabinoids. Medicinal forms of THC may have legitimate indications; however, indiscriminate legalization of so-called medical marijuana has had significant detrimental and perhaps unintended consequences. In a clinical sample of 80 adolescents, Thurstone et al.17 found that 39 (48.8 percent) of the adolescents obtained marijuana from someone with a medical marijuana license. None of the adolescents were registered medical marijuana users. Compared with adolescents who never obtained marijuana from someone with a medical marijuana license, these adolescents were more likely to report very easy marijuana availability, friends who did not disapprove of regular marijuana use, and use of marijuana more than 20 times per month in the past year. They also had more substance use problems in comparison to adolescents who did not obtain marijuana from a registered medical marijuana user. It would not be unanticipated that increasing marijuana availability in states legalizing recreational use would have similar or worse deleterious effects for adolescents.

Is Marijuana Addictive?

Contrary to common belief, marijuana is addictive. Estimates from research suggest that about nine percent of users become addicted to marijuana; this number increases among those who start young (to about 17 percent, or one in six) and among daily users (to 25-50 percent). Thus, many of the nearly seven percent of high school seniors who (according to annual survey data) report smoking marijuana daily or almost daily are well on their way to addiction, if not already addicted (besides functioning at a sub-optimal level all of the time).

Long-term marijuana users trying to quit report withdrawal symptoms including irritability, sleeplessness, decreased appetite, anxiety, and drug craving, all of which can make it difficult to remain abstinent.  These withdrawal symptoms begin within about one day following abstinence, peak at two to three days, and subside within one or two weeks following drug cessation. Behavioral interventions, including cognitive-behavioral therapy and motivational incentives (i.e., providing vouchers for goods or services to patients who remain abstinent) have proven to be effective in treating marijuana addiction. Although no medications are currently available, recent discoveries about the workings of the endocannabinoid system offer promise for the development of medications to ease withdrawal, block the intoxicating effects of marijuana, and prevent relapse.

An additional danger associated with marijuana use observed in adolescents is a sequential pattern of involvement in legal and illegal drugs. Marijuana is frequently a stepping stone that bridges the gap between cigarette and alcohol use and the use of other drugs (e.g. cocaine, heroin). This stage-like progression of substance abuse, known as the gateway phenomenon, is common among youth from all socioeconomic and racial backgrounds.18

Rising Potency

The amount of THC in marijuana samples confiscated by police has been increasing steadily over the past few decades. In 2009, THC concentrations in marijuana averaged close to 10 percent, compared to around four percent in the 1980s. For a new user, this may mean exposure to higher concentrations of THC, with a greater chance of an adverse or unpredictable reaction. Increases in potency may account for the rise in emergency department visits involving marijuana use. For experienced users, it may mean a greater risk for addiction if they are exposing themselves to high doses on a regular basis. However, the full range of consequences associated with marijuana’s higher potency is not well understood, nor is it known whether experienced marijuana users adjust for the increase in potency by using less.

Health Risk Underestimated

Health risks associated with marijuana use are often underestimated by adolescents, their parents, and health professionals. Today, there are newer, stronger forms of marijuana available than that which existed in 1960; current forms of marijuana are known to be three to five times more potent. Parents underestimate the availability of marijuana to teens, the extent of their use of the drug, and the risks associated with its use. In a 1995 survey, the Hazelden Foundation found that only 40 percent of parents advised their teenagers not to use marijuana, 20 percent emphasized its illegal status, and 19 percent communicated to their teenagers that it is addictive.19 Marijuana is considered a “gateway drug,” one that often leads to abuse of even more dangerous substances. Most adolescents who use other illicit drugs say that marijuana was the first drug they used. It is often intentionally used with other substances, such as alcohol or crack cocaine. Phencyclidine (PCP), formaldehyde, crack cocaine, and codeine cough syrup are often mixed with marijuana without the user’s knowledge.20 Chronic psychotic psychiatric diseases have also been linked to LSD, PCP, and amphetamine use, and daily marijuana use in young women has been associated with a five-fold increase in depression and anxiety.21 Epidemiological evidence suggest a link between cannabis use and psychosis.

Parental Monitoring Important

Research shows that appropriate parental monitoring can reduce drug use, even among those adolescents who may be prone to marijuana use, such as those with conduct, anxiety, or affective mood disorders.22

Columbia University’s National Center on Addiction and Substance Abuse (CASA) found that adolescents were much less likely to use marijuana if their parents stated their disapproval.23 In 2011, past month use of illicit drugs, cigarettes, and binge alcohol use were lower among youth aged 12 to 17 who reported that their parents always or sometimes engaged in monitoring behaviors.  This is compared to youths whose parents seldom or never engaged in monitoring behaviors. The rate of past month use of any illicit drug was 8.2 percent for youths whose parents always or sometimes helped with homework compared with 18.7 percent among youth who indicated that their parents seldom or never helped.24

To address the issue of drug abuse, the American College of Pediatricians encourages parents to become involved in drug abuse prevention programs in the community or in the child’s school and take advantage of the “family table.” Columbia Center for Alcohol and Substance Abuse found that teens who have frequent family dinners (five to seven per week) were less likely to have used marijuana.25 Parents should learn what they can do to oppose the legalization of marijuana such as work with elected officials against the drug’s legalization and consider a candidate’s positions on this important children’s issue when making voting decisions. The American College of Pediatricians encourages legislators to consider the establishment and generous funding of more facilities to treat marijuana addiction. Finally, children look to their parents for help and guidance in working out problems and in making decisions, including the decision to not use drugs. Parents should be role models, and not use marijuana or other illicit drugs.

The National Clearinghouse for Alcohol and Drug Information (NCADI) offers an extensive collection of publications, videotapes, and educational materials to help parents talk to their children about drug use. For more information on marijuana and other drugs, contact: National Clearinghouse for Alcohol and Drug Information, P. O. Box 2345, Rockville, MD 20847; 1-800-729-6686. Additional helpful information is provided at the following websites:,, and

Principal Author: Donald Hagler, MD, FCP
Originally posted January 2007
Revised /August 2013

A PDF of this statement is available by clicking here.

For more information, view this College webpage, Health Effects of Marijuana Use.

The American College of Pediatricians is a national medical association of licensed physicians and healthcare professionals who specialize in the care of infants, children, and adolescents. The mission of the College is to enable all children to reach their optimal physical and emotional health and well-being.


1. National Institute on Drug Abuse. Drug Facts. December 2012.

2. DHHS Substance Abuse and Mental Health Services Administration. National Survey on Drug Use and Health (NSDUH). 2011.

3  NSW Commission for Children and Young People. “Suicide & Risk-taking Deaths of Children & Young people.” 2010. Accessed March 15, 2013.

4. Ashton, C.H. “Pharmacology and Effects of Cannabis: A Brief Review,” British Journal of Psychiatry, no. 178 (2001):101-6.

5. Ibid.

6. Meier, M. H., Caspi, A., Ambler, A., Harrington, H., Houts, R., Keefe, R. S.E., McDonald, K., Ward, A., Poulton, R. & Moffitt, T. E. Proceedings of the National Academy of Sciences109,  no. 40 (2012):E2657–E2664.

7. Ibid.

8. Skosnik, P.D., Krishnan, G.P., Aydt, E.E., Kuhlenshmidt, H.A., & O’Donnell, B.F. “Psycholophysiological Evidence of Altered Neural Synchronization in Cannabis Use: Relationship to Schizotypy,” American Journal of Psychiatry, no. 163 (October, 2006):1798-805.

9. Mittleman, M.A., Lewis, R.A., Maclure, M. “Triggering Myocardial Infarction by Marijuana,”   Circulation 103, no. 23 (2001): 2805-9.

10. Mehra, R., Moore, B.A., Crothers, K., Tetrault, J.  & Fiellin, D.A. “The Association Between Marijuana Smoking and Lung Cancer, A Systematic Review,” Archives of Internal Medicine, no. 166 (2006):1359-1367.

11. Nistler, C., Hodgson, H., Nobrega, F., Hodgson, C.J., Wheatley, R. & Solberg, G. “Marijuana and Adolescence,” Minnesota Medical Association. (September 2006). Accessed March 15, 2013.

12. Daling, J.R., Doody, D.R., Sun, X. “Association of Marijuana Use and the Incidence of Testicular Germ Cell Tumors,” Cancer, no. 115 (2009): 1215–1223.

13. Mehra, R., Moore, B.A., Crothers, K., Tetrault, J. & Fiellin, D.A. “The Association Between Marijuana Smoking and Lung Cancer, A Systematic Review,” Archives of Internal Medicine, no. 166 (2006):1359-1367.

14. Simon, S., “Study Links Marijuana Use to Testicular Cancer,” American Cancer Society. September 12, 2012. Accessed March 28, 2013.

15. National Institute on Drug Abuse. Drug Facts. December 2012. Accessed March 15, 2013.

16.  Meeks, J.J., Sheinfeld, J. & Eggener, S. E. “Environmental Toxicology of Testicular Cancer,” Urologic Oncology: Seminars and Original Investigations 30, no. 2 (March–April 2012): 212-215.

17. Thurstone, C., Lieberman, S.A.& Schmiege, S.J. “Medical Marijuana Diversion and Associated Problems in Adolescent Substance Treatment,” Drug and Alcohol dependence 118. no. 2-3 (2011): 489-92.

18. Motivational Enhancement Therapy and Cognitive Behavioral Therapy for Adolescent Cannabis Users: 5 Sessions. Accessed March 12, 2013.

19. Hazelden Foundation. National Survey Show Parents’ ActionsContradictTtheir Beliefs ConcerningTeen Marijuana Use. July 20, 1999.

20. Nistler, C., Hodgson, H., Nobrega, F.T., Hodgson, C.J., Wheatley, R. & Solberg, G. “Marijuana and Adolescents,” Minnesota Medicine, (September 2006):49-51.

21. Patton, G.C., Coffey, C., Carlin, J.B., Degenhardt, L., Lynskey, M. & Hall, W. “Cannabis Use and Mental Health in Young People: Cohort Study,” British Medical Journal 325, no. 7374 (November 23, 2002):1195-8.

22. National Institute on Drug Abuse: National Institutes of Health; US Department of Health and Human Services. Marijuana: Facts Parents Need to Know. Revised March 2011.  Accessed January 29, 2013.

23. DHHS Substance Abuse and Mental Health Services Administration. National Survey on Drug Use and Health (NSDUH). 2011. . Accessed March 12, 2013.

24. Columbia Center for Alcohol & Substance Abuse. National Survey of American Attitudes on Substance Abuse XIV: Teens and Parents. August 2009. Accessed March 12, 2013.

25. Columbia Center for Alcohol & Substance Abuse. The Importance of Family Dinners VII. September 2011. Accessed January 29, 2013.