Article written by
Dipak HemrajHead of Research and Education
Content reviewed by
Dr. Lewis JasseyMedical Director - Pediatric Medicine
Table of contents
We know too little about cannabis to say for sure that it will stunt a child’s growth, physically or mentally. However, this doesn’t only apply to cannabis: the same is true of many prescription medications. Just as we can ask: “what are the long-term effects of cannabis on a child’s developing brain and body?” we can ask: “What are the long-term effects of benzodiazepines (sedatives) on a child’s brain and body?”
Regarding height and weight, it is difficult to show any definitive evidence of change due to many other variables that can impact, such as diet, exercise, and other comorbid conditions. The fact is, we just don’t know the complete picture yet when it comes to cannabis and its impact on human growth.
When it comes to cannabis use, these are the six main factors that seem to determine how much it impacts a child’s or adolescent’s growth rate:
- Strength and concentration of tetrahydrocannabinol (THC).
- The presence, strength, and concentration of other cannabinoids, such as cannabidiol (CBD), cannabigerol (CBG), cannabichromene (CBC), cannabinol (CBN), and tetrahydrocannabivarin (THCV). Terpenes may also modulate cannabinoids’ mechanism of action. Epidiolex, for example, is a CBD-only prescription medication that is very well tolerated compared to the anti-seizure medications they are usually prescribed, which have serious side effects such as brain fog, confusion, unsteadiness, muscle weakness, and addiction.
- Frequency of cannabis use.
- Age of first use.
- Use of other prescription drugs.
- Use of other substances, such as alcohol, tobacco, and other drug abuse.
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Does Marijuana Stunt Growth? What the Science Says
Cannabis is a complex botanical substance that contains many cannabinoids, terpenes, and flavonoids, all with different effects in different dosages (biphasic effects). Most of the conversation regarding children centers around THC-rich cannabis and its impact on a child’s brain development. However, not all cannabinoids have the same level of psychoactivity or effects on the brain as THC.
There are certainly some concerns that THC use during one’s childhood and teenage years may impact the brain’s development and/or structure. This is because the endocannabinoid system (ECS) plays a huge role in brain development. Adding phytocannabinoids during this crucial period may impact future behavior, concentration, learning, memory, and personality. However, cannabis is not just all THC; even with THC, low doses may be helpful for chronic pain as it has a far better safety profile compared to antipsychotics or opioids, even for children. Some children with conditions like autism or cancer may even benefit from THC with careful dosing.
CBD, for example, is very well-tolerated by the human body and has far less impact than benzodiazepine-based sedatives. Granted, we do not know the whole story behind CBD and its long-term effects yet, but logic dictates that it has far less dramatically an impact on a child’s brain than benzodiazepines. One advantage of cannabis and phytocannabinoid-based medications is the reduced chance of deadly overdose and a far better safety profile. For this same reason, CBD-based Epidiolex is now a Schedule V drug available on prescription for those with some types of epilepsy.
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Possible Ways Cannabis Can Impact Development
Most evidence for cannabis’ impact on growth is based on rodents and other animal models. Still, a growing number of studies in humans indicate that exposure to THC-rich cannabis when young can cause long-term and possibly even permanent adverse changes in the brain.
There is also some evidence that consumption of THC-rich cannabis during pregnancy can impact a child when born. Still, there is little to go on in this area, as studying the impact of some medications on pregnant women can be very difficult, with an even larger number of variables to consider than usual.
- Studies on rats show that exposure to THC before birth, after birth, or during adolescence display problems with specific learning and memory tasks later in life. A cross-sectional study of marijuana users aged between 16 and 18 found that marijuana users demonstrated slower processing speed and poorer verbal learning, memory, and sequencing abilities.
- One rat study shows that exposure to THC during adolescence is associated with structural and functional changes in the hippocampus, including cognitive impairment. Hippocampal changes have been observed in regular human users as well.
- One rat study shows that exposure to THC in adolescence is associated with an altered reward system, increasing the likelihood of self-administrating other drugs. Brain scans of regular cannabis users have shown lower dopamine levels, which play a key role in how the brain processes motivation, pleasure, and reward.
- One study finds that boys who were regular users of cannabis before and during puberty were 4.6 inches shorter by the time they were 20:
“Plasma concentrations of luteinizing hormone, testosterone, and cortisol were significantly higher in the marijuana-addicted boys, but growth hormone levels were significantly lower.”
- The same study finds that boys who smoke marijuana go through puberty earlier.
- Little is known about the association between a child’s or adolescent’s cannabis use and long-term body weight changes.
- Some studies suggest that using cannabis may speed up the metabolism and reduce energy storage, resulting in a lower body-mass index (BMI). One study suggests that:
“[M]aybe marijuana is a metabolic regulatory substance that increases body weight in low-weight individuals but not in normal-weight or overweight individuals.”
- Smoking cannabis during pregnancy is associated with a lower birth rate in offspring.
How Cannabis Can Improve Quality of Life for Young People
It is important to realize that cannabis is so much more than just THC and that even THC can be beneficial as a medication in young children, just as many intoxicating medications can be. Cannabis contains compounds with far lower levels of psychoactivity and intoxication that can be medically and therapeutically useful for children. Thanks to the entourage effect, other cannabinoids, terpenes, and flavonoids can be used to mitigate some of the negative side effects associated with THC, boosting THC’s anti-inflammatory properties. This could make cannabis very useful for managing conditions like cancer, inflammatory bowel disease (IBD), and juvenile idiopathic arthritis (JIA).
Moreover, unlike many medications, death via an overdose of cannabis alone is more theoretical than a practical concern. Usually, deaths that involve cannabis involve the ingestion of another drug as well, where there may have been a drug-drug interaction or another health complication. This means that cannabis has a safety profile that most drugs do not have, even over-the-counter ones like ibuprofen.
Although cannabis use is best avoided for young people, medical cannabis is a different argument. Compared to prescription opioids, benzodiazepines and antipsychotics, cannabis has a far better safety profile where the dangers can be mitigated by careful dosing, utilizing other cannabinoids, and choosing the appropriate route of administration. Then, it is possible to find the optimal dose for a pediatric patient, where the benefits outweigh the potential harms.
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The Bottom Line
Medical cannabis has the therapeutic potential to relieve many health problems, including those suffered by the young. However, we do not know much about the impacts of regular cannabis use in young people. There are some harms associated with non-medical use where dosage and cannabinoid ratios are not considered. There may also be a case for using single phytocannabinoid compounds that can be standardized and easily reproduced, making the effects far more predictable.
More research is needed in this area, but clinical trials involving a psychoactive substance applied to children can be difficult. This means we must rely on animal studies, observational studies of those who are already cannabis users, real-world evidence (RWE), and the handful of clinical studies where pediatric patients are the main participants (usually with severe conditions where other medications have failed).
Overall, there is plenty of promise that medical cannabis can have therapeutic effects on children and adolescents suffering from serious health problems. However, non-medical use is generally best avoided for the young. Some even suggest that cannabis use when young is not ideal, but after a certain age (many give the age of 21 or 25 and over) could prove beneficial and even help boost the brain. So, it is best to be discerning when a young person is using cannabis, medical or otherwise.
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