Last year the National Academies of Sciences, Engineering, and Medicine convened a committee of experts to conduct a comprehensive review of the literature regarding the health effects of marijuana use. The committee considered more than 10,700 studies for their relevance and arrived at nearly 100 different research conclusions related to marijuana (cannabis) or cannabinoid use and health. Their findings were recently published in a 400-page report.
Here are nine things about the effects of marijuana you should know based on this report:
1. The terms marijuana and cannabis refer to all parts of the plant Cannabis sativa L., including the seeds, the resin extracted from any part of such plan, and every compound, manufacture, salt, derivative, mixture, or preparation of such plant, its seeds, or resin. The compounds that cause intoxication and may have medicinal uses are cannabinoids, a class of chemical compounds that acts on cannabinoid receptors in cells that represses neurotransmitter release in the brain. The marijuana plant contains more than 100 cannabinoids. Currently, the two main cannabinoids from the marijuana plant that are of medical interest are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD).
2. There is substantial or conclusive scientific evidence for only three medical benefits of cannabis or cannabinoids: treating chronic pain in adults; treatment of chemotherapy-induced nausea and vomiting, and nausea after chemotherapy; and improving symptoms of multiple sclerosis.
3. There is substantial evidence of a statistical association between cannabis use and increased risk of motor vehicle crashes. Self-reported cannabis use or the presence of THC in blood, saliva, or urine, has been associated with 20 to 30 percent higher odds of a motor vehicle crash.
4. In states where cannabis use is legal, there is increased risk of unintentional cannabis overdose injuries among children. There is insufficient evidence to support or refute a statistical association between cannabis use by adults and death due to cannabis overdose.
5. Recent cannabis use (within the past 24 hours) impairs the performance in cognitive domains of learning, memory, and attention. A limited number of studies also suggest there are impairments in cognitive domains of learning, memory, and attention in individuals who have stopped smoking cannabis. Cannabis use during adolescence is related to impairments in subsequent academic achievement and education, employment and income, and social relationships and social roles
6. Cannabis use is likely to increase the risk of developing schizophrenia and other psychoses—the higher the use the greater the risk. However, cannabis use does not appear to increase the likelihood of developing anxiety, depression, or posttraumatic stress disorder.
7. The evidence suggests that any cannabis use is related with increased suicidal ideation (i.e., suicidal thoughts or preoccupation with suicide), augmented suicide attempts, and greater risk of death by suicide. Studies reveal that heavy cannabis use (used 40 or more times) is associated with a higher risk of suicidal ideation and suicidal attempts.
8. There is substantial evidence that initiating cannabis use at an earlier age is a risk factor for the development of problem cannabis use. There is moderate evidence that during adolescence the frequency of cannabis use, oppositional behaviors, a younger age of first alcohol use, nicotine use, parental substance use, poor school performance, antisocial behaviors, and childhood sexual abuse are risk factors for the development of problem cannabis use. Anxiety, personality disorders, and bipolar disorders are not risk factors for the development of problem cannabis use
9. Most of the studies reviewed indicate an association between cannabis use and use of or dependence on other substances (including, alcohol, tobacco, and other illicit drugs), with some data indicating this effect is more pronounced in younger individuals and is dependent on the dose or frequency of cannabis use.