As more and more teenagers use marijuana — a 2018 survey found 2.1 million middle and high school students have vaped the substance — research that looks into the health effects of cannabis is more important than ever. And now, a study published on Monday in the Journal of Neuroscience suggests that marijuana may alter the teenage brain after just one or two joints, NBC News reported.
In this small study, researchers scanned the brains of 46 14-year-olds from Ireland, England, France, and Germany. They found that those smoked one or two joints had higher brain volumes than those who didn't. Specifically, the teens who used marijuana had more gray matter, a mass of cells that affect how humans mature over time, in their brains than those who did not use it.
While researchers have not yet determined whether higher brain volume is necessarily bad for a person's health, we know that the brain naturally decreases in volume as a person ages, according to the National Institutes of Health (NIH). The researchers' findings suggest that marijuana creates abnormalities in the brain's normal aging, or pruning, process.
"At the age at which we studied these kids (age 14), cortical regions are going through a process of thinning," Hugh Garavan, lead author of the study and a professor of psychiatry, told NBC News. When marijuana was introduced, however, the increased amount of gray matter "disrupted this pruning process" and affected the normal maturation process, Garavan explained.
Given the size of the study, however, it is important to take the findings with a grain of salt. As more questions arise regarding the effects of marijuana on the young brain, more research must be done to pinpoint the impact it has on health.
Marijuana may also slow a person's reaction time, make their heart race, and affect short-term memory
In addition to changing the teenage brain, marijuana can also have other effects on the human body. When tetrahydrocannabinol, or THC, the main psychoactive component in marijuana, reacts with the body's cannabinoid receptors, a person may have slower reaction times than normal, INSIDER previously reported.
Additionally, marijuana can make a person's heart race temporarily. The National Institute on Drug Abuse said this feeling can last between 20 minutes and three hours and may cause a person's heart to increase up to 50 beats per minute.
A person who uses marijuana may also experience issues with their short-term memory since the substance affects how the brain processes information, according to a 2013 study.
Research has indeed shown that marijuana does affect the brain in long- and short-term ways, so people who use or are considering using the drug should consider the risks before proceeding.
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