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Did you know…

  • Marijuana has a chemical in it called tetrahydrocannabinol, better known as THC. All forms of marijuana are mind-altering (psychoactive). In other words, they change how the brain works. A lot of other chemicals are found in marijuana, too — about 400 of them, some of which are cancer causing. Using marijuana can also lead to disturbed perceptions and thoughts, and marijuana use can worsen psychotic symptoms in people who have schizophrenia. Additionally, there are higher rates of depression, anxiety, and suicidal thinking among people who use marijuana when compared to people who don't use. Teens who started using marijuana before age 15 are more likely to suffer from anxiety and depression in early adulthood. A new study shows that smoking marijuana is associated with a 40% increase risk of psychosis, and the risk is greater among regular and frequent users. Marijuana is addictive. More teens are in treatment with a primary diagnosis of marijuana dependence than for all other illicit drugs combined.

Source: SAMHSA, 2006

  • Young people who use marijuana weekly have double the risk of depression later in life.

Source: Patton, GC et al. "Cannabis use and mental health in young people: cohort study." British Medical Journal, 325:  1195–1198, 2008

  • Heavy Marijuana users are more likely than non-users to be diagnosed with schizophrenia later in life. A recent study found that people who had used marijuana more than 50 times before the age of 18, had a three fold increased risk of developing schizophrenia later in life.

Source: "Cannabis use in adolescence and risk for adult psychosis: longitudinal prospective study," British Medical  Journal, 325:1212-1213, 2007

  • Marijuana can cause increased heart rate and make some users extremely anxious or paranoid. 

Source: NIDA. Marijuana: Facts for Teens, 2008

  • Heavy marijuana use impairs young people's ability to concentrate and retain information.

Source: Pope HG et al., "Early-onset cannabis use and cognitive deficits: what is the nature of the association?" Drug and Alcohol Dependence, 69(3): 303-310, 2007.

  • The short-term effects of marijuana can include problems with memory and learning.

Source: NIDA. Marijuana: Facts for Teens, 2008

Thom Kessler, LMFT, RAS