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Does Marijuana Cause Mental Illness?


The cannabis plant, which yields marijuana, has been cultivated for centuries for the production of hemp fiber and for its medicinal and psychoactive properties. Surveys indicate that marijuana is the most commonly used illegal drug in the United States. Its use peaked in the 1970s when about 60 percent of high school seniors reported having used it and 11 percent reported daily use. The use of marijuana declined in the 1990s and rose again in around 2002, with about 48 percent of high school seniors reporting having used it. Today, the association between marijuana and mental illness has caused a renewed interest in its use.

An association between marijuana use and mental illness, particularly psychosis, has long been recognized. Recently, with a better understanding of brain function and pharmacology, researchers have renewed their interest in this subject. Although present statistics suggest that marijuana accounts for 10 percent of all cases of psychosis, epidemiological evidence suggests that the number could be higher. Patients with psychosis are at higher risk for cardiovascular and metabolic diseases compared to the general population.

Researchers at Yale University School of Medicine report that cannabinoids, which are the active ingredient in marijuana, can induce acute transient mental illnesses, particularly psychotic symptoms, including paranoia and acute psychosis in some individuals. As to why some people experience this and others don't remains unclear. The Yale researchers also note that in individuals with an established psychotic disorder, cannabinoids can exacerbate or worsen psychotic symptoms. These exacerbations can persist long past the period of intoxication. Available evidence suggests a causal relationship between marijuana, psychosis and the development of schizophrenia. However, because most people who use marijuana don't develop these disorders, the Yale researchers theorize that cannabinoids interact with another component, perhaps genetic risk, that predisposes them to psychosis. Dysfunction of the CB1 receptor has been proposed as a possible risk factor and is being further investigated.

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Worldwide, researchers are studying the effects of marijuana on mental health. In 2008, French researchers published a study in which they evaluated 32 cannabis abusers along with 30 healthy controls using self-reports. Their study showed that cannabis abusers were more likely to have mood and anxiety disorders and to experience high levels of psychological distress, trait anxiety, physical anhedonia, and sensation seeking than controls. A similar study from the Netherlands showed that acute cannabis use can cause memory impairment persisting for months after its use. Cannabis, however, showed no changes in brain anatomy based on MRI reports.

There are at least six distinct cannabinoids present in marijuana. The two most important active ingredients in marijuana are the cannbinoids Delta 9-tetrahydrocannabinol (delta9-THC) and cannabidiol (CBD). The amounts of these two components present in marijuana can vary and they both cause different effects. In recent years plant engineering has maximized levels of delta9-THC, thereby increasing the plant's potency. Delta9-THC increases anxiety and levels of intoxication, sedation and psychotic symptoms, whereas CBD reduces anxiety and acts on the amygdala and anterior and posterior cingulate cortexes, affecting the limbic and paralimbic regions.

The pharmacological effects of delta9-THC vary with the dose, route of administration, experience of the user, vulnerability to psychoactive effects and setting of use.


DC D'Souza Cannabinoids and Psychosis, Int Rev Neuorbiol 2007l 78: 289-326.
P Fusar-Poli, J Crippa, et al, Distinct effects of delta9-tetrahydrocannabinol and cannabidiol on neural activation during emotional processing, Arch Gen Psychiatry, January 2009; 66(1): 95-105.



People sing praises to marijuana all the time like "It relaxes me. Or it makes me realize things that I never realized before". They often become upset and sometime hostile in it's defense (maybe a mental side effect **)But rarely does anyone tell about the NEGATIVE. It can make you feel like your are loosing your mind. When I tried it, I found out the negative effects the HARD way. The effects were delayed but when it hit, it HIT! My heart started racing, I felt like I didn't know where I was, who I was, I felt like I was dying and that I would black out at any moment. The world did not make any sense and I was not in my right mind. I felt like the world would fall down as if I was loosing all sense of direction. The sleepier I got, the WORSE it got. I became frantic and very frightened. My mind was spinning out of control and ANY feeling I had (scared, happy, relaxed) was enhanced by 10 times. It made no sense at all. I just wanted it all to end. But, there is NO quick fix. Only time. I felt like I would be left permanently insane. I'm just giving my experience and hopefully anyone who has the stupid idea to try marijuana to relieve whatever stress they are dealing with reads this. Marijuana CAN cause psychosis in ANY amount and you do NOT have to be a frequent user. IF YOU ARE NOT PRESCRIBED MARIJUANA, DO NOT USE IT!
Sounds like you just had a panic attack, which is fairly common when you're not in good company and trying it for the first time. Just like alcohol, marijuana isn't for everybody and likewise affects people differently. Most people don't feel comfortable drink copious amounts of booze for their first time and end up enjoying the experience either. Like all mind-altering substances, there are risks to take into consideration. Once you become familiar with the substance, you'll see its benefits and disadvantages for yourself. Also, like alcohol, marijuana comes in different strains, varieties and potencies. The effects are just as subtle as drinking wine compared to vodka. Obviously mental health is the biggest risk when consuming dissosciatives, and truly a person should abstain from all forms. Marijuana is not some silent killer, or instant insanity-inducing drug. Just like alcohol, there are people at the top who consume marijuana and lead perfectly normal lives; just as there people at the bottom, poster children for drug abuse, who partake as well. Take all risks into consideration and experiment as you will. Research is key. Claiming that you've experienced psychosis after your first time is alarmist and false. You got high and didn't know what to expect. Remember to research and evaluate for yourself. Keep an open mind and enjoy your life. Thanks for reading.
Actually it sounds like psycosis to me, I have experienced the same thing, as have other people I know. Alcohol has its own problems and should be outlawed also if you ask me, but cannabis is definitely more dangerous for your mental health. It may not happen the first time like this poor guy, but if you abuse it you are going to find out the hard way how horrible psycosis is. I was unable to function properly for 6 months because of psycosis and its the worst experience of my life.
The name of the article is: Does Marijuana Cause Mental Illness? But the author trying so hard to proof, that can cause, but at the same time, there is not proof. Even in his on article...