Cannabis and the Adolescent Brain

Granville Stanley Hall, American psychologist and the founder of the child study movement in his era, wrote in 1904 about the exhilarating turbulence of adolescence:

These years are the best decade of life. No age is so responsive to all the best and wisest adult endeavor. In no psychic soil, too, does seed, bad as well as good, strike such deep root, grow so rankly or bear fruit so quickly or so surely.

Hall said optimistically of adolescence that it was “the birthday of the imagination,” but he also knew this age of exhilaration has dangers that include impulsivity, risk-taking, mood swings, lack of insight, and poor judgment. Across the national landscape, the legalization of marijuana has created an industry boom that continues to employ over a quarter million of the U.S. population and transcend revenues of over $10 billion annually. Marijuana continues to be the most popularly used illicit drug in the nation next to nicotine and alcohol. Illinois is the first state to undergo a legislative process to legalize marijuana’s sales as well as the 11th state to permit its recreational use overall. This entire legalization has both positive and negative trends within our state for adolescents and minors that are becoming exposed to marijuana use at earlier ages under 21. With the legalization of its recreational use in these states, many wonder about the ripple effects, despite the age limits, that marijuana’s legalization can have for the youth when accessibility seems to be… high in need of weed control (puns intended). Additionally, a Monitoring the Future survey has shown that when perception of marijuana’s risk drops, use of the drug rises simultaneously. This perceived risk of marijuana has been declining over the last decade. In 2014, less than 40 percent of high school seniors said they believed regular marijuana use was very risky — the lowest proportion since the 1970s.

“There are a lot of open questions” about the long-term effects of marijuana, says Susan Weiss, PhD, Director of the Division of Extramural Research at the National Institute on Drug Abuse (NIDA). “But there’s a growing literature, and it’s all pointing in the same direction: Starting young and using frequently may disrupt brain development.” Brain imaging and related research has started to emphasize that from childhood to adolescence, the brain is seen as pruning back in size to accommodate for the lack of neural connections not being used. In this sense, brain development is becoming more faster and effective with ease in specifically attuned activities of enjoyment. Recent studies from the University of Wisconsin-Milwaukee’s neuropsychology lab reflect how the adolescent brain continues to grow in remembering what it learns, making accurate judgments, and thinking critically as part of its developmental milestones. Using cannabis in this golden opportunity of brain development minimizes the brain’s process to optimally become as smart and healthy as possible. These studies provide substantial and growing evidence in the literature that cannabis use impacts the structural development of the adolescent brain and ultimately injures cognition and academic performance. Another study from Duke University highlighted that citizens from New Zealand who were surveyed longitudinally from childhood until age 38 had dramatic and contrasting outcomes between users and non-users of cannabis. From childhood into adulthood, those that regularly used cannabis starting from their teenage years were seen to have lost 8 IQ points. The younger the cannabis users, the greater the IQ decline over the years. Additionally, adults who started in their early teenage years of smoking pot were seen to have done poorly on tests related to memory and decision-making. 

For different states, legalizing marijuana has proven very lucrative to the extent that individual state marijuana tax receipts alone are on a monumental incline. Even prior to the United States, Canada and Uruguay are the pioneering nations to have first legalized and regulated the recreational use of marijuana. Current medical use of marijuana reflects promising signs of treatment for muscle spasms, chronic pain, seizure disorders, and nausea from cancer chemotherapy. The National Institute of Health is supporting more research and funding for cannabidiol, the chemical component of the marijuana plant not seen to demonstrate the mind-altering effects related to marijuana use. Neuroscience research literature now indicates that tetrahydrocannabinol (THC) is the main psychoactive (mind and mood altering) ingredient that manifests the signature high for its users, but THC is not at all risk-free or without bodily consequence. As regulations wane and the marijuana industry has gotten more lobbying power, THC-laced products include the peddling assortments in the form of vape-ables, smokables, edibles, topicals, and insertables become accessible and create a potential for confusion and harm (i.e. THC-laden candy that looks like the Sour Patch Kids as one form). In contrast to the 1960s and 70s, current-day high school and college students that use cannabis experience a more potent effect since the THC content is far greater and outweighs the effects of former cannabis users from previous decades. Potency has arisen from rates of 1-2% THC content back then to as much as 20-25% THC content in our modern-day context, with cannabis content rates rising to as high as 76% THC on some products. Additionally as a reflection on how it has the nature of being a gateway to other harder substances, some experts in adolescent drug use state, “Look, you start with pot at thirteen. When looking back at this kind of kid, when he was on pot, he was around people trying other things, and you have less of an ability to say no to other drugs because of your still-developing frontal lobes. You’re probably already high anyway, so piggybacking on pot with another drug doesn’t seem all that bad.”

The Center for Addiction Medicine from Massachusetts General Hospital reflects that 1 in 5 young adults between 18-25 years old are regular users of cannabis whereas teens 13-17 years old are the next age group of highest concentration and most frequent users across the nation. Current national statistics highlight that there is an increase of youth marijuana use with the current trends of legalization. With contemporary public policy as well as the biology of the plant itself changing, it becomes important to note the shift in the marijuana landscape of the nation, and there are multiple public health implications that will need attention. Within the short-term outcomes, marijuana use has been associated with various impairments in learning and memory, decision-making, and sustaining attention. It is not uncommon for these difficulties to wax and wane long after the signature high wears off for users. Based on the negative trends, heavy marijuana use during adolescence and young adulthood has demonstrated poor grades and school performance, greater likelihood of dropping out, lower life satisfaction, patterns of long-term unemployment, and an increased dependence upon welfare. A more current tendency is to place blame on marijuana use for its deleterious effects from peer influence, emotional distress, and poor life outcomes with problem behaviors. More studies that examine the causal relationship between its use and poor life outcomes are forthcoming.  

For parents who find themselves in need of ongoing conversation, reflection, and support – here are some important reminders: 

• Maintain reflective dialogue! Keep pursuing open lines of communication and the parent-teen connection with clear expectations. Talk with your teen regularly about the changing laws and the shifts from credible and reliable sources about drug use facts and effects. Acquiring knowledge and educating yourself and the family will be an important part of the ongoing fight with awareness, prevention, and intervention efforts before arriving at erroneous conclusions. Open and candid reflections can lead to greater mutual understanding while fostering a healthy parent-teen relationship. 
• Substance use and mood disorders can emerge from frequent marijuana use, which can lead to other addiction concerns in serious cases. Marijuana use has proven health problems as breathing difficulties, paranoia, hallucinations, anxiety, and even at times reactions with psychoses. The research trends are clear: the younger the age of use, the greater the abuse and more mental health concerns. 
• THC content has also been seen as part of the current vaping phenomenon. Smoking and vaping THC-rich extracts (dried leaves, seeds, flowers, and stems) from the marijuana plant cannabis sativa and cannabis indica are on the rise, and this is a process called dabbing. THC over-activates brain regions and results in altered senses, impaired body movements, mood changes, difficulties with thinking and problem-solving, and memory loss with deactivated learning. You can read more about adolescent vaping trends here.  
• Peer-reviewed studies on medical marijuana indicate the myriad of benefits and positive associations with its use and decrease of negative bodily symptomatology. However, the research emphatically indicates that casual marijuana use still demonstrates structural brain changes in gray matter of the amygdala and nucleus accumbens, the region of the brain linked with motivation and processing. Research data reflects that the more joints smoked in a week, the larger and abnormal the alterations in shape, size, and density of this region. 
• More research considerations from Northwestern University gives evidence that frequent marijuana use can correlate with poor memory and diminishing returns on learning and communication. Chronic and early users of marijuana are now linked with the brain changes and functioning of those that demonstrate schizophrenia, and early marijuana abuse has been linked with developing an early onset of schizophrenia. The amount of drug used, the age at first use, and genetic vulnerability have all been shown to influence this relationship. The strongest evidence to date concerns links between marijuana use and substance use disorders and between marijuana use and psychiatric disorders in those with a pre-existing genetic or other vulnerability. 
• Long-term effects of chronic marijuana use as a teenager has been linked with memory-related brain structures shrinking, collapsing, and decreasing in neuron volume in relation to working memory and performance on memory tasks. The relationship between cannabis use and working memory impairments are associated. 
• Smoking five marijuana cigarettes is equal to smoking a full pack of tobacco cigarettes, according to the American Lung Association. Marijuana smoke, which users inhale and try to hold in their lungs for as long as possible, also contains 50 to 70 percent more cancer-causing chemicals than cigarette smoke contains. (The use of a bong, a pipe that filters cannabis through water, is no insurance against these deleterious chemicals since the principal cancer-causing ingredient in marijuana is benzopyrene, which does not dissolve in water.)
• A consequence of pot smoking usually referred to as having “the munchies” is an uptick in appetite with a neurobiological basis. Italian scientists recently isolated the probable cause: marijuana appears to affect the brain’s hypothalamus, which regulates food intake. 
• Endocannabinoids, the body’s own natural cannabis, is the body’s neurochemical linked with the runner’s high and internal state of calmness. Cannabinoids are linked with neurogenesis, bone density, improved mood, and fine-motor control; they are also connected with pleasure, anti-inflammatory properties, and analgesic in alleviating pain. The body releases this neurochemical while working out in exercise through sweat (a motivating factor to exercise). 
• Allow for your teen to pursue activities as playing an instrument, mindfulness training, creating art, and pursuing a strong social network to improve fluid intelligence and working memory while providing an alternative to the effects of cannabis use. 

All this research with the effects of marijuana on the teen brain should become a public service announcement for parents everywhere, and the message is evidentially transparent: adolescent brains are not as resilient as adult brains when it comes to marijuana. Teenagers are especially vulnerable to the drug because they are at a critical stage in the development of two of the most sophisticated parts of their brains—the frontal and prefrontal cortex—and these are precisely the parts most affected by marijuana. This is not minor or incidental. These brain regions are used every day for basic cognitive tasks, whether it’s abstract thinking, the ability to change one’s behavior in relation to changing demands in the environment, or the inhibition of inappropriate responses. The paradigm to address marijuana use, misuse, and abuse needs to transition from just being seen as a moral issue to that of a public health issue as well. Public health practitioners are now making this more evident in educating cannabis users about the potential deleterious effects of marijuana, regardless of its legal status, in the nation with an ever-increasing growth rate among adolescents and young adults.