Marijuana is also known as Cannabis; is a shredded leaves, stem, and flower bud of the plant called Cannabis sativa plant. Marijuana could either be eaten, smoked, vaporized, and brewed, but many are fond of smoking it. Marijuana is an intoxicating substance due to the chemical content of the plant known as tetrahydrocannabinol (THC). According to Mehmedic et al. (2010) in a Potency Monitoring Project, the average THC content of marijuana has increased from 1% in 1972 to 4% in 1990 and nearly 13% in 2010. Today, most marijuana sold at the retailed market is found to contain 30% THC or more. The drifting concentration of the THC makes it difficult to determine the short and long-term effect of marijuana.Marijuana has the same effect on the brain as similar to the effect of heroin, alcohol, and cocaine. It often depends on the quantity, quality, and method of consumption, marijuana tends to produce a euphoric feeling by stimulating the brain cells to release dopamine chemical in the brain. According to the National Institute of health, Marijuana takes longer time for it to take effect in the brain when ingested through food. Relaxation could be accompanied by other change of mood. Some other users of marijuana often experience heightened sensory perception with the appearance of color appearing more vividly and noise becoming more louder. Marijuana is frequently reported to alter the perception of time and increase food appetite, known as the munchies.The impact of marijuana on a human can vary from individual, with other factors such as how often the user has been taking it, how often the user has gotten high, and how the strength of the drugs matters. A marijuana chemistry expert at Terra Tech Corp, a California agriculture company, reported that the side effect of THC includes sedation, elation, relaxation, anxiety, tachycardia, sedation, pain-relief and short-term memory recall issues.Marijuana is an illicit substance under the federal law; the United States government originally banned Marijuana in 1937. In 1996, Colorado was the first state to legalize the use of marijuana, followed by other 27 states in the U.S.; this step made marijuana to be easily accessible to both young and old. According to a study tagged “Monitoring the Future”, the study reveals that 45.3% of U.S. 12th grader is making use of marijuana in their lifetime, with 22.9% reported to have been using marijuana in their previous 30 days of life activities.In 2012, a study carried out by the Washington State Healthy Youth Survey reveals that about 19% of 10th-grade student and 27% 12th-grade students are users of marijuana; these data doubled the figure of even adult smokers. The Washington teenager explains how easy it is for them to get marijuana.The use of marijuana at teenage age could significantly impact the brain development, thereby causing decreased brain activity, fewer neural fibres in some areas and smaller than hippocampus which controls learning and memory.A Northwestern Medicine study in 2014 reveals that teen marijuana users memory-related structure in the brain appears to shrink as the uses of marijuana persist; this appears as a sign of decreasing brain neurons. The abnormalities would remain normal after two years of total avoidance of marijuana; it indicates that a drug like marijuana has a long term effect on the brain (Maria, 2014).People who started taking marijuana after the ages of 21 years do not experience the same effect as the teenage users. Long-term users stated that they often have difficulties to think clearly, multitask, organizing their thought, or remember things easily. Comparatively, sustained uses of marijuana can also slow the reaction time of many individuals.A study published by the University of Montreal in the Journal of Development and Psychopathology in 2016 reveal the result of research with include 300 students. It was discovered that those that have started smoking form the ages of 14 perform poorly in some cognitive task than the non-smokers. However, those that started smoking at the age of 17 are not found with similar disabilities. The study shows that the rate of school drop-out was very higher among those that started smoking marijuana while in their teens.Scientific EvidenceThere are several studies which investigate the exact effect of marijuana on the brain, a study in 2010 reveal that marijuana abuser have a decrease right medial orbital and a prefrontal cortex volume, the volume was in correlation with age initiation of marijuana (Churchwell et al.,2010). Another study in 2010 on marijuana effect on brain show association with brain morphometry, there has been no link between age and cortical gyrification in a teenager that are marijuana users. Furthermore, marijuana users show a declined concavity of sulci and sulci thinning in the temporal frontal, and parietal lobe unlike the non-marijuana users. Marijuana is highlighted to disrupt normal brain trajectories.Recently, in a study carried out which focus on the effect of marijuana on the frontal lobe structure. According to Cousijn et al. (2012), it was revealed that hippocampal and amygdala volume of teenager correlates with the negative amount of marijuana usage. The hippocampal and amygdala structure of the frontal lobe reacts to the use of marijuana by making these structures to become smaller. The amygdala and hippocampal are known to be responsible for learning and cognitive coordination of the body. Some other author added that the cerebellum of marijuana abuser appears larger in volume that non-abuser (Cousijn et al., 2012).In another study which focuses on the volume of the grey matter at the age of 12 years of some student that are said to have not started using marijuana. The study discovered that the orbitofrontal cortex of the brain appears bigger in volume before initiation of marijuana, after initiation, the volume of the orbitofrontal cortex of the brain become reduce. Conversely, the orbitofrontal cortex is known to play a major role in the behavioral control (Cheetham et al., 2012).Peer pressure to look cool as believed by many other could influence teenager to take substances like alcohol. The common form of Marijuana that a teenager often have access to include the following;In Form of Smoke: Smoking is the most popular and frequent access to marijuana, a user rolls up pipe or a substance called bong. Marijuana is popularly smoke using paper wrapped or in a tobacco wrapper leaf. Smoking of marijuana is the most dangerous form of taking marijuana. User burns the THC content of marijuana and inhales it, passing through the mouth, nose and lungs.In Form of a Vaporizer: Often, medical use of marijuana is administered to a patient through a vaporizer. The vaporizer helps to extract the THC content of marijuana by heating to a high degree of temperature. The user inhales the vapour of the marijuana.In Tea Form: Marijuana could also be presented in the form of tea, though it is the least utilized form marijuana usage among teenager. The tea form of marijuana is not as dangerous as the other forms; the active ingredient in the marijuana is known to be suppressed by the tea ingredients.Effect on Learning Teenage utilization of marijuana has been connected to the scope of formative and social issues. A 2012 investigation of more than 1,000 people completed from birth to midlife found that tenacious marijuana utilization was related to neuropsychological decline across many domains, including cognitive, memory issues and declining IQ. The suspension of marijuana may not fully restore the neuropsychological functioning in teens that has once been exposed to marijuana (Meier et al., 2012). However, a contradictory study reported that no difference was found in the mental capability of a male which was monitored through their teenage life to their mid-thirties. Marijuana on frequent or intermediate uses would have a dimming effect on the brain. Affect the memory, ability to think and reason within, and beyond of content of what is taught, user often experience difficulties to concentrate, learn new thing, and even make a good decision (Dougherty et al., 2013)Effect on School PerformanceSince marijuana alters learning and other behavior that is related to concentration and reasoning. The lack of motivation for marijuana users makes them associate with a peer that likely to involve in range of violence and risk-taking activities (McCaffrey et al., 2010). For teens indulging and depending on marijuana, their behaviors are such as poorer school performance, increase risk of dropping out, decrease interest in school activities, increase school absenteeism. In Washington State, it was discovered that student whose use marijuana either frequently or intermediately are most likely to have lower grades when compared to a student that is a non-marijuana user.Problematic BehaviorsMany studies shown has shown that the use of marijuana from an early age in life increases the risk of developing problems in future, these may include behavioral difficulties, social disadvantages, and peer problematic affiliations. A longitudinal study of marijuana usage in 2008 among users between the ages of 14 to 25 in New Zealand birth cohort, it was discovered that high utilization of marijuana in the teenage life and post-teenage age often result into the adverse outcome in later life. Intense use of marijuana is linked with a poor educational background, welfare dependence, unemployment, laziness, lack of social relationship, aggressiveness, lack of life satisfaction etc. The result from the study gave a conclusion that added up to the growing body showing the adverse consequences of marijuana use at an early life. Comparatively, the study established a correlation that marijuana disrupts the behavior of individuals (Ferguson & Boden, 2008).Some researcher concluded that marijuana is capable of triggering riskier behavior in a teenager, these include; increase the level of chances of leaving home, early stage sexual activities, immature sexual conduct, unplanned pregnancy. Marijuana increased the risk of accident among driving teenagers; as they tend to take the risk to take many dangerous steps while behind the steering. Marijuana is also linked with an increased number of criminal behavior among teenagers such as vehicle theft, rape, break-and-enter offences and many others.Increased Mental IssuesOverdose of marijuana among teenager in linked with a range of mental problems such as fear, psychosis, anxiety and depression. According to a study in Sweden in 2002, heavy marijuana increased the risk of schizophrenia event in later life (Arseneault et al., 2002). However, there have been numerous study that linked schizophrenia or psychosis with the utilization of marijuana, especially among teens whose family background has a lot to do with psychosis and schizophrenia (Copeland et al., 2013).Sometimes, many feelings of fear and psychosis among teens are a result of an accumulation of marijuana does. A teen might start to skip regular event as the doses of marijuana alter their psychotic level and reactions. Kids might starts to disturbed and panic as their condition is deviating from the normal. In such state, teens find it hard to differentiate between many real events and may not respond well to any attempt from people around them in an attempt to rescue them from such disorder. Moreover, frequent use of marijuana could lead to paranoia; this condition often turns most teen’s mental health issue into some cases that tend to wreck their future if not rehabilitated quickly. In some case where a teenager has a trait of schizophrenia in their genetic make-up, the use of marijuana could trigger such condition and makes it worse. Such event often leads to a long-lasting psychosis disorder, and even makes it permanent (Rubino and Parolaro, 2008).Among teenagers who are an abuser of marijuana, the potential for anxiety and depression is also increased. Some studies are somewhat controversial in their approach that heavy marijuana dose leads to depression; some suggest that the reason is linked with depression could be as a result of that marijuana decline learning leading into failing grade, which could be the main cause of depression. However, a study carried out among teenagers in high school in 2012 reveals that increasing frequency of marijuana is linked to depression symptoms (Horwood et al., 2012).Conclusively, continuous and intermediate usage of marijuana at early age place teenagers at a huge risk of developing an emotional problem, depression, mental issue, schizophrenia, and psychosis. In many cases, marijuana usage among teenager often leads to poor academic performance and disrupt coordination of cognitive mental health. Learning and taking a sound decision becomes very difficult for marijuana users in the years after. In future, marijuana abusers live become difficult in every aspect they find themselves. Despite the fact that marijuana is being prescribed medically, abusers should be severely cautioned of over-accumulation of the THC, as it persists in their adulthood.