An increasing amount of medical research over the past decade has revealed a myriad of serious risks to the health and quality of lives of adolescents from their use of marijuana. The risks are not the same for responsible adult use. Moreover, with the potency of marijuana increasing each year, these studies will become outdated and if anything, will be found to understate the effects of cannabis.
Susceptibility of the Adolescent Brain
During the adolescent years the brain undergoes its biggest period of development since the womb. Biological insulation and wiring between nerve cells increases rapidly, and unused connections are discarded, making the brain pathways more effective. Adolescent brains don't
finish this development until the mid 20s for women and late 20s for men. Until these ages, their neurological wiring is being laid down. Intake of marijuana during the teen years is detrimental to brain growth and establishment of a strong network of connections. Marijuana is a complex plant containing at least 85 chemicals called cannabinoids, one of which is THC. THC is able to link to special cannabinoid receptor sites throughout the brain (called the endocannabinoid system). When THC interacts with the endocannabinoid system in the developing teen brain, it interrupts and alters the rapidly changing connections between nerve cells.
As a result, THC affects memory and learning (the hippocampus), novelty, emotion and appetite (the amygdala), motor skills (the basal ganglia), real time coordination, selective attention and time sense (the cerebellum), reward mechanisms (the nucleus accumbent) and finally, executive functions (the cortex).
The frontal lobe of the cortex, which governs executive functions (such as judgment, reasoning, impulse control, decision-making, problem solving, planning, execution, empathy, compassion and flexibility) is the last part of the brain to develop. Its more "mature" brain functions help teens grow into responsible adults. But until the frontal lobe is fully formed in the mid 20s, teens’ “GO” mechanism in the brain is more dominant than their “STOP” mechanism. Alteration of brain development by heavy use of marijuana before the frontal lobe is fully formed has been shown to have a negative effect on emotion, impulse control, planning and follow through abilities, and much more.
Females More Susceptible
Girls appear to be most affected in terms of their brain development and stunted emotional development. A September 2014 study found that because of their estrogen hormones,
females are more susceptible to the effects of THC. In the first ever study to assess gender differences in sensitivities to THC, a National Institute on Drug Abuse (NIDA) funded study found that females develop tolerance to THC more quickly and have an increased vulnerability to negative side effects such as anxiety, panic attacks, paranoia, depression and addiction.
Previous studies also found women were more prone to marijuana abuse and dependence, and that withdrawal symptoms of irritability, sleep disruption and decreased food intake were more severe.
A 2002 investigation in the British Medical Journal of a longitudinal Australian study concluded that weekly use in female teenagers predicted an approximately twofold increase in risk for later depression and anxiety, and that daily use was associated with an over fivefold increase.
Marijuana is Addictive. Period.
Although marijuana is not as addictive as drugs like tobacco or heroin it affects the reward centers of the brain in the same way that other addictive drugs do. These drugs of abuse result in the brain adapting to unnatural levels of reward and stimulation from the release of more dopamine than with natural rewards like food, sex and social interaction.
THC bypasses the brain’s receptors which when stimulated slowly release dopamine and this causes the brain to be flooded with dopamine. As a result, the brain stops making so much of its own dopamine. The lack of dopamine can cause depression which can lead to further use.
Overall, 9% of users become addicted, but importantly this increases to 17% (or one in six) with those who start in their adolescent years. This is not only due to their developing brains but also the speed of addiction, which is greater with adolescents. Between 25-50% of daily or near daily adolescent users get addicted. Bear in mind that many studies are outdated because marijuana product development is occurring so fast. With increasing potency, these numbers are likely to worsen.
In 2010, 4.5 million people in the United States met the criteria for abuse and dependency, as established by the American Psychiatric Association. According to the National Institutes of Health (NIH), there are more marijuana addicts in the U.S. than Americans addicted to prescription pain relievers, cocaine, tranquilizers, hallucinogens and heroin combined.
Many chronic marijuana users who attempt to go “cold turkey” experience physical withdrawal symptoms. Within three days, these symptoms begin to peak, making abstinence challenging to maintain. A Harvard neuropsychologist has noted that she has seen more physical withdrawal symptoms in adolescents in the last decade, including trouble sleeping, severe
mood swings, inability to handle stress, headaches, blurred vision, nausea and flu like symptoms lasting for one week. Local treatment centers note the same increases. Note that these symptoms occur in the absence of other substances.
Moreover, it takes teens longer to recover from addiction. This is because teens don’t have the skills built up or the underlying brain foundations that help them know how to make reasonable, rational decisions.
Treatment and rehab centers across the country report that most of the adolescents they see (85%) have a marijuana use disorder where they are dependent or abusive of marijuana. In California, we have already seen a huge escalation in the number of users seeking treatment for abuse or dependence. Between 1992 and 2008, there was a near quintupling of the number of treatment admissions due to marijuana.
Decreased Functioning in School The harm done to a child's educational progress is real and strong, and is even greater than the risks of addiction or the harm done to the brain. Marijuana affects learning and can destroy motivation (amotivational syndrome), interfere with memory, and cuz loss of concentration which gradually affects self-esteem. Kids often say it makes them feel “lazy” or “dumb.” Grades drop and ambitions disappear.
Memory impairment is a serious consequence of chronic or long-term use of marijuana, and this effect can be experienced long after marijuana use is suspended.
One study found difficulties in verbal story memory, along with impairments in learning and working memory for up to six weeks after cessation of use. Another study found that long term heavy cannabis users show impairments in memory and attention that endure beyond the period of intoxication and worsen with increasing years of regular cannabis use.
Research further shows that adolescents who smoke marijuana on weekends only, over a two-year period, are nearly six times more likely to drop out of school than non smokers, more than three times less likely to enter college than non smokers, and more than four times less likely to earn a college degree. Whether marijuana causes this is unknown but we do know there are strong effects on learning and motivation.
Loss of IQ points
Heavy youth marijuana use may result in cognitive deficits. A stunning landmark 2012 longitudinal 25-year study in New Zealand of 1,037 subjects showed on average an eight-point decline in IQ. Youth who used marijuana persistently and heavily before age 18 and into adulthood experienced the drop by age 38. This drop is irreversible.
The IQ loss did not happen with adults: those who used marijuana frequently after age 18 did not experience a drop in IQ. The results were later re-examined (after being criticized for failing to control for socioeconomic status) and it was definitively concluded that the decline in IQ could not be attributed to socioeconomic factors alone.
Even Casual Use in Young Adults is Linked to Brain Abnormalities
A 2014 study by Northwestern University Medicine and Massachusetts General Hospital/Harvard Medical School showed that even those young adults (ages 18 to 25) who were not heavy or chronic users (some using once or twice a week) showed significant abnormalities in two key brain regions (the amygdala and nucleus accumbens). These regions are important in emotion and motivation and are also associated with addiction.
The more joints a person smoked, the more abnormal the shape, volume and density of grey matter (i.e., where most cells are located in brain tissue) were in the brain regions, according to MRI images. This is the first study that has been funded to research the effects of causal versus heavy use of marijuana by teens.
Adverse Socioeconomic Consequences
A recent study conducted by an international team of researchers led by UC Davis and Duke epidemiologists concluded that people who use marijuana end up with lower paying, less skilled and less prestigious jobs and experience more financial, work-related and relationship problems. Regular marijuana users ended up in a lower social class than their parents. The study looked at 947 of the participants in the 2012 New Zealand study, discussed above, who
were observed over a 25-year period.
Note that these users experienced more financial difficulties than those who were alcohol dependent. The study also found that the financial, work and relationship difficulties worsened as the number of years of regular cannabis use progressed.
These issues did not arise because of prosecution or criminal records. The study observed more antisocial behavior in both work and relationships. It also found lower motivation to achieve as well as abuse of alcohol and harder drugs. The study found these problems began in adolescence, with antisocial behavior and depression and higher levels of impulsivity.
Mental Illness Risks Include Psychotic Symptoms and Schizophrenia
Numerous studies have found that marijuana can trigger mental illnesses or worsen underlying conditions such as anxiety, depression, bipolar disorders, paranoia, psychotic breaks and schizophrenia. Suicidal thoughts can also be a by-product. Studies show that marijuana increases the risks of occurrence of these mental illnesses, which are even more pronounced in those with a family history.
A wide array of studies show that the more chronic the marijuana use and the earlier in life that use begins, the greater one’s chances are of developing psychosis typified by delusional thinking or experiencing the onset of schizophrenia, characterized by a breakdown in thought processes.
Treatment centers report they are seeing more and more teens experiencing psychotic breaks. Hospitals are seeing what is known as "cannabis-induced psychosis", a diagnosis which was added to the Diagnostic Statistical Manual (DSM) in 2013.
Even if adolescents and teens don’t become dependent (and the majority do not), it’s the alteration of brain structure and function that is at the root of mental health problems later in life.
Physical Health Effects of Marijuana
Studies show that marijuana use is associated with accidents and injuries, bronchitis, acute cardiovascular events, gastrointestinal issues, and possibly infectious diseases and cancer. With the much higher THC levels in today’s marijuana, these physical health effects are likely to worsen.
Respiratory System. Marijuana smoke contains many more chemicals than tobacco smoke. The American Lung Association states on its website that marijuana smoke “contains a greater amount of carcinogens than tobacco smoke. In addition, marijuana users usually inhale more deeply and hold their breath longer than tobacco smokers do, further increasing the lungs’ exposure to carcinogenic smoke.” A wealth of medical study backs up these contentions.
New Zealand scientists determined that smoking one joint of marijuana was comparable in effect on airflow obstruction of between two and one half and five tobacco cigarettes. Marijuana smokers hold their breath about four times longer than cigarette smokers, allowing more time for extra fine particles to deposit in the lungs.
Moreover, marijuana is packed more loosely than tobacco so there is less filtration and more particles are inhaled. Respiratory symptoms found by Yale researchers include shortness of breath, frequent wheezing, frequent phlegm and chronic bronchitis. UCLA scientists found additional effects including a potential predisposition to the development of respiratory malignancy as a result of carcinogens.
Cardiovascular System. Within minutes of inhaling marijuana fumes, a person’s heart rate increases and can double, blood vessels expand, the eyes redden and a variety of impacts on the heart and cardiovascular systems can occur.
Overdoses from Dabbing. There have been reported overdose experiences after dabbing. Users can inhale so much concentrated smoke at once that they pass out.
Link to Cancer. Whether smoking marijuana is a trigger for causing cancer, especially lung cancer, remains an open question. More research is needed, which is mixed on this issue. However, the evidence is increasingly tilting toward the conclusion that marijuana use can be a risk factor.
People with preexisting immune system deficiencies (for example resulting from AIDS or chemotherapy) can be more susceptible to developing cancer or a recurrence of cancer because of an enzyme that marijuana smoke contains. Another toxic chemical in marijuana smoke was found to damage a person’s DNA and increase their risk for developing cancer, according to a 2009 study by British scientists.