Second, context is important. Many of these findings are meant as summations of fact, not endorsements or condemnations. For example, the report found evidence that driving while high increased the risk of an accident. But the report also notes that certain studies have found lower crash rates after the introduction of medical cannabis to an area. It's possible that cannabis makes driving more dangerous and that the number of crashes could decrease after introduction if people take proper precautions.
We'll work on providing context to these findings over the next few days but wanted to share some of the initial findings first.
With that in mind, here are some of the most striking findings from the report:
- There was conclusive or substantial evidence (the most definitive levels) that cannabis or cannabinoids, found in the marijuana plant, can be an effective treatment for chronic pain, according to the report, which is "by far the most common" reason people request medical marijuana.
With similar certainty, they found that cannabis can help treat muscle spasms related to multiple sclerosis and can help prevent or treat nausea and vomiting associated with chemotherapy.
- The authors found evidence that suggested that marijuana increased the risk of a driving crash.
- They also found evidence that in states with legal access to marijuana, children were more likely to accidentally consume cannabis.
We've looked at these numbers before and seen that the overall increases in risk are small — one study found that the rate of overall accidental ingestion among children went from 1.2 per 100,000 two years before legalization to 2.3 per 100,000 two years after legalization. There's still a far higher chance parents call poison control because of kids eating crayons or diaper cream, but it's still important to know that some increased risk could exist.
- Perhaps surprisingly, the authors found moderate evidence (a pretty decent level of certainty and an indication that good data exists) that cannabis was not connected to any increased risk of the lung cancers or head and neck cancers associated with smoking. However, they did find some limited evidence suggesting that chronic or frequent users may have higher rates of a certain type of testicular cancer.
- Connections to heart conditions were less clear. There's insufficient evidence to support or refute the idea that cannabis might increase the risk of a heart attack, though there was some limited evidence that smoking cannabis might be a trigger for a heart attack.
- There was substantial evidence that regular marijuana smokers are more likely to experience chronic bronchitis and that stopping smoking was likely to improve these conditions. There's not enough evidence to say that that cannabis does or doesn't increase the risk for respiratory conditions like asthma.
- There was limited evidence that smoking marijuana could have some anti-inflammatory effects.
- Substantial evidence suggests a link between prenatal cannabis exposure (when a pregnant woman uses marijuana) and lower birth weight, and there was limited evidence suggesting that this use could increase pregnancy complications and increase the risk that a baby would have to spend time in the neonatal intensive care unit.
- In terms of mental health, substantial evidence shows an increased risk of developing schizophrenia among frequent users, something that studies have shown is a particular concern for people at risk for schizophrenia in the first place. There was also moderate evidence that cannabis use is connected to a small increased risk for depression and an increased risk for social anxiety disorder.
- Limited evidence showed a connection between cannabis use and impaired academic achievement, something that has been shown to be especially true for people who begin smoking regularly during adolescence (which has also been shown to increase the risk for problematic use).
- One of the most interesting and perhaps most important conclusions of the report is that far more research on cannabis is needed. Importantly, in most cases, saying cannabis was connected to an increased risk doesn't mean marijuana use caused that risk.