Introduction
Cannabis, usually known as marijuana, is a plant that produces a psychotropic chemical. It is one of the most commonly used illicit narcotics globally and has been used for recreational, medical, and spiritual purposes for ages. Despite being prohibited in many nations, it is easily accessible and a favorite recreational substance among teenagers (Quaranta et al., 2022). Health and medical specialists have long been concerned about teen marijuana use.
Due to its numerous hazards and rising popularity among teenagers, marijuana usage is a severe problem. Several studies have shed light on the possibility that marijuana use can harm the brain irreversibly (Haines-Saah et al., 2021). This increased attention has focused on the specific effects of marijuana use on the developing adolescent brain. This paper discusses in detail the impact of marijuana use on the brains of adolescents aged 12 to 18.
Background
Teenagers are using marijuana more frequently now than in previous years. Recent Centre for Disease Control and Prevention estimates that 22% of teenagers between 12 and 18 report using marijuana within the last 30 days (2022). However, numerous middle and high school students—8% of eighth, 19% of the tenth, and 22% of twelfth graders—reported vaping marijuana in the past year.
It is commonly known that marijuana usage among teenagers carries some hazards. These dangers include cognitive decline, addiction, and detrimental physical and mental health effects (Centre for Disease Control and Prevention, 2022). Additionally, because the adolescent brain is still developing, marijuana usage has the potential to cause long-term, possibly even irreversible, damage.
Theories of Marijuana Usage
The stepping stone theory is one of the marijuana theories. According to Pouille et al. (2021), the stepping stone theory suggests that marijuana abuse frequently results in drug abuse of other substances. It is believed that marijuana has pharmacological properties that encourage users to try other drugs.
The theory holds that someone who enjoys using marijuana is more likely to enjoy cocaine or other more potent drugs than marijuana. Moreover, factors that cause someone to start using marijuana are also expected to cause them to use hard drugs. In addition to harming someone’s brain, it also introduces them to drugs like heroin and cocaine, which causes even more damage.
It is important to remember that not all marijuana users go on to use other drugs like cocaine, but many heroin users started out using marijuana. Adolescents might be introduced to marijuana smoking because they are told it has benefits, such as reducing stress, but the effects of smoking are transient. Such occurs since, after the effects of marijuana wear off, the problems that had caused the stress are still present, and the individual must deal with them to prevent further strain.
The gateway theory is the other model explaining marijuana usage among teens. Nyarko et al. (2020) suggest that the gateway theory argues that drug abuse follows a predictable pattern from adolescence to adulthood. Marijuana use among young people is more likely to continue as adult behavior. Marijuana is a gateway drug for other hard drugs because it makes accessing other drugs easier for those who can obtain marijuana, an illegal substance.
Chemistry of Cannabis
Although cannabis has been used for therapeutic and recreational purposes for centuries, our understanding of its chemical composition is still in its infancy. The primary psychoactive substance in cannabis, delta-9-tetrahydrocannabinol (THC), is the most researched and well-known (Nelson et al., 2020). THC is a lipid-soluble molecule with a molecular structure similar to the body’s naturally occurring ligand, anandamide. Calapai et al. (2020) suggest that the “high” associated with cannabis is produced when it binds to cannabinoid receptors in the brain. It has thus been linked to alterations in mood, perception, memory, and appetite.
Cannabidiol (CBD) is another critical component in cannabis (Nelson et al., 2020). Although it lacks the intoxicating qualities of THC, it nonetheless has several medical advantages. It is effective for treating various illnesses due to its analgesic, anti-inflammatory, and antispasmodic qualities. Moreover, it is believed to lessen THC’s overall intoxicating effects.
Cannabis also contains several additional cannabinoids, terpenes, and flavonoids in addition to these well-known substances. Chemical substances known as cannabinoids interact with the body’s endocannabinoid system. They are believed to have various physiological effects, including enhancing relaxation and mood, as well as decreasing pain and inflammation (Nelson et al., 2020). The numerous cannabis cannabinoids’ roles and interactions, however, are not well understood.
Terpenes are fragrant substances in many different plants, including cannabis. They have medicinal qualities of their own and add to the flavor and aroma of the plant. According to Nelson et al. (2020), Terpenes are thought to collaborate with cannabinoids to strengthen their effects and add to cannabis’s overall medicinal value. Finally, flavonoids are polyphenolic substances that are also present in a variety of plants, including cannabis. They contribute to the scent and flavor of the plant, similar to terpenes, but have also been linked to several health benefits, including antioxidant and anti-inflammatory effects.
Therefore, cannabis’s chemistry is highly complex, and it is currently being researched. Individuals can only hope that their knowledge of this plant will expand as new chemicals are discovered and existing ones are further studied. The therapeutic potential of cannabis may become apparent as people understand more about it.
How Marijuana Travels to the Brain
THC impacts the brain by targeting this crucial human organ. THC and CBD in marijuana are quickly absorbed from the Gastrointestinal tract or lungs and enter circulation through the vascular system. THC and CBD then proceed to the brain from there. THC can cross the blood-brain barrier because it is lipid- and water-soluble, allowing it to interact with the brain’s cannabinoid receptors (Stella et al., 2021).
The hippocampus and other brain regions related to memory, learning, and coordination are where CB1 receptors are primarily located. The blood-brain barrier is actively crossed by CBD, which is more soluble in lipids (Calapai et al., 2020). CBD then binds to CB2 receptors, which are primarily found in the immune system but can also be found throughout the brain.
Once in the brain, THC and CBD connect with the cannabinoid receptors there, activating downstream signaling pathways that result in the varied consequences of marijuana use. The pleasure, relaxation, and increased appetite associated with marijuana usage are brought on by THC activating the CB1 receptor, which subsequently triggers a significant release of the neurotransmitter dopamine (Calapai et al., 2020).
Users of marijuana claim to feel relaxed and experience euphoria when it enters their brains. It is crucial to remember that the effects of marijuana depend on a variety of factors, including the social context, the user’s experience and psychological history with the substance, as well as a wide range of personality effects and the intricacy of its chemical makeup. CBD has analgesic, anti-inflammatory, and anxiolytic effects by activating CB1 and CB2 receptors.
Effect of Marijuana Use on Adolescent Brain
The adolescent brain is a period of rapid development and maturation. It is susceptible to the effects of substances such as marijuana due to the presence of higher levels of cannabinoid receptors, which can mediate the effects of THC. Brain development is affected by multiple factors, including genetics, environment, and experience.
The adolescent brain undergoes structural and functional changes that influence learning, memory, behavior, and emotional regulation. Marijuana use has a direct and significant effect on the development of the adolescent brain. Recent research has identified numerous changes to the brain structure, intelligence, learning and memory, attention and emotion regulation, and pharmacological effects that result from marijuana use.
Brain Structure
Teenage marijuana use has been shown to have various negative impacts on brain anatomy. Regular marijuana usage has been linked to changes in the cerebral cortex’s volume, the brain area in charge of higher-order cognitive processes, including language, judgment, and social processing (Cyr, 2022). This has been linked to changes in the general organization of the brain, as well as problems with memory and learning.
White matter and gray matter, which comprise the cerebral cortex, each have distinct roles. The cells that comprise the gray matter, which is crucial for learning, memory, and decision-making, include nerve cells and other cells that process information. According to Hung et al. (2020), marijuana usage among teenagers causes the gray matter volume in the hippocampus, cerebellum, and prefrontal cortex to diminish. Learning and memory problems, as well as other cognitive issues, may result from this.
Teenagers who use marijuana may see changes in their brain’s white matter and the amount of gray matter. The white matter affects how quickly and efficiently information is processed, facilitating the connection between various brain regions. Regular marijuana use has been linked to altered white matter structure in the brain, which can hinder communication across different brain regions (Hung et al., 2020). Cognitive functions, such as attention, executive function, and memory, may be affected.
Teenage marijuana usage has also been associated with long-term changes in brain function and effects on brain structure. Long-term marijuana use has been linked to an increase in the activity of reward and pleasure-related brain pathways, raising the possibility that regular marijuana use can result in psychological dependence (Mendes et al., 2022). This can increase the likelihood of engaging in dangerous activities like drinking and raise the risk of mental health conditions like depression and anxiety.
Intelligence
Teenage marijuana use has been associated with lowered IQ. According to Lorenzetti et al. (2020), teenagers who regularly use marijuana are likely to have lower IQs than their friends who do not. It is believed that marijuana usage impairs the brain’s capacity to process and remember new knowledge, which leads to a decline in intellect. Moreover, marijuana use has been linked to abnormalities in neuronal development that can affect the brain’s capacity to remember and learn new information.
Academic performance may be affected by marijuana use. According to the Centers for Disease Control and Prevention (2022), teenagers who consistently use marijuana are likely to quit school, not get a college degree, or perform worse academically than their friends who do not. The effects of marijuana on concentration, attention, and motivation are likely responsible for this decline in academic performance.
Learning and Memory
Adolescent marijuana use has been found to lead to impaired learning and memory. According to Cyrus et al. (2021), marijuana use in adolescence can lead to difficulties in concentration, knowledge, and memory recall. These impairments are thought to be due to marijuana’s effects on neurotransmitters involved in these processes, such as glutamate and GABA. THC alters the way the brain processes information and responds to stimuli. The changes are most precise in the hippocampus, a part of the brain. When a lot of marijuana is used, the many THC receptors in the brain change how the brain works, which can affect memory.
The hippocampus is a part of the brain that combines sensory information with motivation and memory, and is responsible for controlling learning. This means that using marijuana can affect memory and learning. Since THC is a steroid, it binds to receptors in the hippocampus (Calapai et al., 2020). This keeps the hippocampus from recovering memories, especially short-term ones.
THC is responsible for losing short-term memory because it kills nerve cells. When people use a lot of marijuana, their nerve cells get damaged and form new structures that stop them from sending any further information to the brain (Stella et al., 2021). When a person takes a lot of marijuana, their information may not be stored in their brain, which makes it impossible for them to remember it. Additionally, THC makes it harder for nerve cells to work properly.
Cannabinoid receptors take in the THC that makes people feel high in the hippocampus area of the brain. When a high amount of cannabidiol affects the nerves in the brain that send information to the brain, users report difficulty remembering things (Stella et al., 2021). Even after the effects of a lot of marijuana wear off, the impact on memory can still affect other things, like learning. Due to how marijuana affects their memory and learning ability, marijuana users often do worse in school than people who do not smoke.
The impact of marijuana on memory is nuanced and individualized. For instance, marijuana use can harm the recognition memory, which is responsible for recalling words seen before smoking. It can also result in memory intrusions and false memories of previously unseen words. Additionally, marijuana use can make recalling specific terms from a list more difficult because users tend to remember some words while forgetting others.
Although it does affect how it functions, marijuana’s THC does not seem to impair memory ultimately. THC-induced memory recall can produce a more selective type of memory formation, where some words are remembered more vividly than others. This differs from conventional memory recall, which involves retrieving information in a linear order. As a result, marijuana’s memory effects can make a person remember some words while forgetting others.
Additionally, regular marijuana use can worsen memory loss because the body’s receptors become tolerant to THC and need more to achieve the same level of intoxication. Due to the higher THC levels necessary for intoxication, this may cause further difficulty in remembering details (Calapai et al., 2020). The effects of marijuana on memory can significantly impact a person’s capacity to create memorable experiences and recall precise information. Therefore, it is crucial to consider how marijuana use may affect teens’ memory and take precautions to lessen its effects.
Attention
Teenagers who use marijuana may find it difficult to concentrate. The ability to pay close attention to a task or activity to complete it well requires concentration. One must pay attention to succeed in their studies, career, and home life. As a result, marijuana use can significantly affect a teen’s capacity for concentration.
Short-term marijuana use can make it hard to pay attention because THC can interfere with the brain’s workings (Lorenzetti et al., 2020). Because of this, a teen who uses marijuana might find it hard to stay focused on the task at hand. Also, long-term marijuana use can cause changes in attention that last longer. People who use marijuana often are more likely to have problems with their attention, memory, and decision-making ability.
Marijuana use can also make it hard for teens to pay attention because it makes it hard for them to sleep and get motivated. People who use marijuana often have trouble sleeping, making them feel tired during the day. Additionally, marijuana use can lower motivation, resulting in apathy, a lack of interest, and difficulty concentrating. Finally, marijuana use can alter a teen’s perception of time, impairing their capacity for concentration. Marijuana users might have a different sense of time, taking longer to complete tasks and being less attentive, which can make it hard for them to stay focused and finish tasks, impacting their performance at school and work.
Emotion Regulation
The ability to regulate emotions can be directly and noticeably impacted by marijuana usage throughout puberty. Adolescence is a critical period of heightened emotion regulation, which can be impaired by marijuana use. During adolescence, there are particularly noticeable physiological changes in the brain regions responsible for decision-making, executive functioning, and the reward system. So, changes in brain development may exacerbate the effects of marijuana on a teen’s ability to regulate their emotions.
The brain circuits responsible for emotional control can be permanently disrupted in adolescents who use marijuana. Marijuana use impacts the brain’s reward system, which is the central system involved in emotional regulation (Cohen et al., 2019). This reward system facilitates learning and reinforces behavior that benefits the individual. Cannabis usage can interfere with this reward system, resulting in less self-control and more impulsive behavior.
Marijuana use raises tension and anxiety levels since its regular users may get dependent on the drug and go through severe withdrawal symptoms, especially when trying to stop. These withdrawal symptoms can cause emotional dysregulation, manifesting as mood swings, anxiety, and depression. Moreover, THC affects the same cellular receptor systems that control emotions. As a result, THC can further impair emotional regulation in addition to the direct effects of marijuana usage on the reward system and self-regulation.
Mental Health
Marijuana’s effects on the brain can be worrying, especially considering it may contribute to mental health problems. The use of marijuana is linked to a higher risk of mental health conditions like schizophrenia, anxiety, and depression. Later-life onset of schizophrenia, frequently marked by delusions, hallucinations, disordered thinking, and decreased social functioning, can be connected. Cannabis constituents, such as THC, can disrupt the dopamine system, which is intimately linked to mental health issues, by interfering with dopamine signaling in the brain (Hurd et al., 2019).
Additional mental health issues can result from marijuana use. The use raises the risk of anxiety disorders, such as generalized anxiety disorder, panic attacks, and post-traumatic stress disorder. Fear, excessive worrying, and physical disturbances may manifest in these cases. Moreover, marijuana usage is linked to a higher chance of developing depression, manifesting as fatigue, difficulty concentrating, and a lack of interest in previously enjoyed activities. Although the connection between marijuana usage and depression is not entirely understood, research points to the brain’s reward system as a potential cause.
Due to THC’s propensity to stimulate the brain’s reward system and change the chemical balance that controls mood, marijuana usage has been linked to an increased risk of suicide. It may be harder to stay sober if you use the drug because of the higher chance of acquiring substance use disorders. Lawn et al. (2022) suggest that using marijuana can make you more likely to experience psychosis. The mental condition known as psychosis causes a person to lose touch with reality and exhibit hallucinations, paranoia, and delusions. Cannabis usage has been linked to a higher risk of psychosis, although the precise mechanism is yet unknown, according to studies.
Addiction and Dependence
Marijuana use among adolescents is a significant problem and can lead to other drug abuse, dependence, and addiction. Early marijuana use in adolescence increases an individual’s risk of developing drug abuse and dependence due to the heightened effects of marijuana. Brain scans have also demonstrated that early-onset marijuana use can damage the hippocampus’s neurons responsible for memory formation and learning (Dhein, 2020). This can lead to an increased risk of addiction to marijuana and other drugs.
Addiction can cause various changes in the brain that lead to physical and psychological dependence. Precisely, marijuana activates cannabinoid receptors throughout the brain’s pleasure centers (Cohen et al., 2019). The brain interprets marijuana as a rewarding experience, which causes an increase in dopamine release and changes in the brain’s reward and motivation systems. Long-term usage of marijuana can cause an individual to develop a tolerance to the drug and dependence on it to feel its effects.
Marijuana addiction can have severe social and economic consequences, including decreased work performance and productivity, increased risk of motor vehicle accidents, and increased risk of criminal behaviors. The most powerful result of marijuana addiction is impaired judgment, which puts individuals at higher risk of dangerous situations such as drug overdose.
Moreover, adolescents with a history of marijuana use often begin experimenting with additional drugs more than those without. They have already established the habit of drug use and are more likely to use additional drugs to increase the effects experienced. As teens are more likely to take risks and engage in behaviors that can lead to even more significant risks, this can lead to polydrug use and substance abuse disorders.
Conclusion
Marijuana usage in adolescents aged 12 to 18 can seriously harm their brain development. Changes in brain structure, intelligence, memory, attention, and emotion control have all been linked to its use. Moreover, marijuana use increases the risk of addiction, dependency, and mental health issues. These changes can have long-term implications for overall health and future success, leading to difficulty in school and adapting to the demands of the adult world. Therefore, teens should place the highest priority on preventing marijuana use and misuse because there are significantly more negative health effects of marijuana use than positive ones.
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