Pot was made out to be a gateway drug that would ruin your brain and lungs. Pot is no longer taboo. More American adults are using the drug than at any time since Ronald Reagan was president, as 18 states and Washington, D.C. have legalized it.
The legality and culture around pot has changed, as have some of the science. Epidemiologists are still concerned about how many Americans are smoking pot, but they admit that it isn't a health hazard, and there is some evidence that a little pot could be a good thing for adults.
According to the National Survey on Drug Use and Health (NSDUH), over 10% of Americans over the age of 26 reported getting high in a given month in 2020. The rate of monthly use in 2010 was double that of 2011.
What are the risks of using cannabis? We summarized the latest science on marijuana's health risks, the areas where there's an absence of evidence that pot is risky, and the surprising reason why.
The risks are real.
There are a few clear health risks to consuming the drug, but many of pot's effects are tangled in conflicting research. Smoking cannabis regularly can cause bronchitis-like symptoms, and research published last month found that chronic cannabis users, who used pot at least four times a week for more than three years, had impaired pancreatic function. There have been cases of daily cannabis users developing pancreatitis without any obvious risk factors.
It has not been proven that regular pot use is associated with higher rates of depression, anxiety and poorer life outcomes like being unemployed.
There is evidence that cannabis can be dangerous when used in certain situations. A recent study found a correlation between an increase in cannabis use and an increase in childhood leukemia, and a separate study found a correlation between cannabis use while pregnant and children having higher rates of anxiety. There is evidence that using pot while pregnant can lead to lower birth weights. Driving a car while high increases the risk of a motor vehicle accident.
It can be an issue with addiction. Cannabis use disorder is a clinical diagnosis of problematic and uncontrollable cannabis use. There is evidence that rates of cannabis use have increased since 2008, but Dr. Kevin Hill, an addiction psychiatrist and professor at Harvard Medical School, told FiveThirtyEight that most people who use cannabis don't have a problem with it.
The 2020 NSDUH found that 4.1 percent of people ages 12 to 17 met the criteria for the disorder, while 14.5% of people ages 18 to 25 had the disorder. The rates of alcohol use disorder were below those of all age groups.
Deborah Hasin, an epidemiologist at Columbia University, said she is very concerned about the increasing use of cannabis by adults because it is associated with poorer quality of life, cognitive decline and impaired educational and occupational employment. According to Hasin, 19.5 percent of people who used cannabis in their lifetimes met the criteria of CUD.
Hasin said that not everybody who smokes marijuana has all of the problems, but the risk is there and it's a greater risk than people think.
Frequent pot use is growing among adults, which increases the risk of developing CUD. The share of people getting at least five days a week increased from 5.8 to 13.8 percent between 2008 and 2019.
Some risks have been overblown.
The image of a pothead is loaded with negative health connotations, from joint smoke causing cancer to the fact that stoners damage their brain with weed. The actual science behind these popular insinuations is far from settled, and in some ways the data points to pot not being the harmful culprit.
Recent research shows that cannabis use is not associated with a higher risk of lung cancer or emphysema. Pot use is associated with an increase in lung function. That doesn't mean that people's lungs are healthier if they use pot, just that they aren't.
Pot has been accused of causing psychosis in movies from the 1950s Reefer Madness era to a fable from the Middle Ages. There is no scientific consensus that cannabis can cause psychosis or schizophrenia in people who wouldn't have otherwise developed the illnesses.
The study found an association between daily consumption of higher THC potency cannabis and developing schizophrenia, which gave more evidence that the potent cannabis sold in America's dispensary was especially risky. The authors of the study did not determine if cannabis had a direct link to schizophrenia. There is strong evidence that genetics play a role in the development of schizophrenia, and a study done in 2021 found that certain genetics had a stronger risk for developing the disease than smoking cannabis.
Carl Hart, a neuroscientist at Columbia, said that the study didn't convince experts that higher potency pot was causing schizophrenia.
Hart said that the studies are poor and crappy. When you look at cat ownership in childhood, it's the same correlation as when you look at a mental illness.
The long-term effects of pot on the brain are more complicated than the caricature of a burned-out pothead would suggest. A review of 56 brain studies found that it was unclear if the structural changes found in cannabisTrademarkiaTrademarkiaTrademarkiaTrademarkias were caused by or preceded cannabis use.
Pot has surprising benefits.
Government agencies like the National Institute on Drug Abuse have spent over $1 billion vilifying cannabis as a uniquely damaging substance, even though pot use has not been linked to higher overall mortality. There is strong evidence that cannabis can provide health benefits. The drug is one of the oldest medicines in the world. Modern epidemiological and animal studies show that cannabinoids, the active compounds in pot, have great promise for treating a wide range of diseases, including cancer and neurological decline, and even the Food and Drug Administration has recognized its medical potential by approving a cannabis-derived drug to treat rare forms of s
Pot has benefits that some studies found to be damaging. A study that followed a group of New Zealand adults for 20 years found that cannabis use was associated with worse gum health, but better cholesterol levels, lower body mass index and reduced waist circumference.
The 2020 study looked at cannabis use by people over the age of 60. The study found that cannabis users exercised more often and had a lower body mass index.
There's evidence that the best way to gauge health for people who are normal weight or slightly overweight is by measuring their body mass index.
The director of NIDA said that cannabis could have benefits for adults.
It was surprising to learn that marijuana users have a lower body mass index than the general population. This is why we need to study it.
Volkow said that she is concerned about increasing rates of cannabis consumption because long-term, daily consumption of cannabis, particularly the high-THC products sold at legal dispensary, can have harmful effects even on the adult brain.
It wasn't clear if there were any negative effects for adults who use cannabis occasionally and in moderate amounts. There is no evidence to suggest that occasional marijuana use has harmful effects. I don't know of any evidence of that. I don't think it's been evaluated
Americans are not waiting for the tests to be done. Millions of adults dose themselves with cannabis every month in a haphazard clinical trial. For some people, that may lead to a smoker's cough and problematic cannabis use, but for others, using pot more often could be a good thing.