Marijuana is the most commonly used illicit drug in the United States (SAMHSA, 2014). Its use is widespread among young people. According to a yearly survey of middle and high school students, rates of marijuana use have steadied in the past few years after several years of increase. However, the number of young people who believe marijuana use is risky is decreasing (Johnston, 2014).
THC acts on numerous areas (in yellow) in the brain.
Long-term marijuana use has been linked to mental illness in some users, such as:
- temporary hallucinations—sensations and images that seem real though they are not
- temporary paranoia—extreme and unreasonable distrust of others
- worsening symptoms in patients with schizophrenia(a severe mental disorder with symptoms such as hallucinations, paranoia, and disorganized thinking)
Marijuana use has also been linked to other mental health problems, such as:
- suicidal thoughts among teens
Marijuana also affects brain development. When marijuana users begin using as teenagers, the drug may reduce thinking, memory, and learning functions and affect how the brain builds connections between the areas necessary for these functions. Marijuana’s effects on these abilities may last a long time or even be permanent. For example, a study showed that people who started smoking marijuana heavily in their teens and had an ongoing cannabis use disorder lost an average of eight IQ points between ages 13 and 38. The lost mental abilities did not fully return in those who quit marijuana as adults. Those who started smoking marijuana as adults did not show notable IQ declines (Meier, 2012).
Is Marijuana addictive?
Contrary to common belief, marijuana can be addictive. Research suggests that about 1 in 11 users becomes addicted to marijuana (Anthony, 1994; Lopez-Quintero 2011).This number increases among those who start as teens (to about 17 percent, or 1 in 6) and among people who use marijuana daily (to 25-50 percent) (Hall, 2009a; Hall, 2009b).
A Rise in Marijuana’s THC Levels:
The amount of THC in marijuana has been increasing steadily over the past few decades (Mehmedic, 2010). For a new user, this may mean exposure to higher THC levels with a greater chance of a harmful reaction. Higher THC levels may explain the rise in emergency room visits involving marijuana use. The THC levels in today’s cannabis is from 3X to 10X more potent than the in the 1970s.
The popularity of edibles also increases the chance of users having harmful reactions. Edibles take longer to digest and produce a high. Therefore, people may consume more to feel the effects faster, leading to dangerous results.
Dabbing is yet another growing trend. More people are using marijuana extracts that provide stronger doses, and therefore stronger effects, of THC (see “Marijuana Extracts“).
Higher THC levels may mean a greater risk for addiction if users are regularly exposing themselves to high doses.
Statistics and Trends:
|Drug||Time Period||8th Graders||10th Graders||12th Graders|
|Monitoring the Future Study: Trends in Prevalence of Marijuana/ Hashish for 8th Graders, 10th Graders, and 12th Graders; 2014 (in percent)*|
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