United States Attorney General Jeff Sessions just announced that he would reverse the Obama-era decision to not prosecute federal marijuana-related crimes in states where the drug has been legalized. And so again, marijuana is in the headlines. But amidst all the buzz, what do we actually know about the health effects of marijuana? This controversial topic could use an injection of calm, rational, fact-based discussion. As a psychiatrist specializing in the treatment of serious mental illness and co-occurring substance use disorders, I can provide a little clarity.
First, although nowhere near as damaging to public health as other drugs including tobacco, alcohol, and opioids, we can’t let cannabis completely off the hook. Many people can use pot safely in moderation, but there are several highly vulnerable groups who should avoid it. Despite numerous claims and even some state medical marijuana laws, there is little-to-no scientific evidence that weed helps any mental illness, and it can be addictive. In fact, there are studies showing that cannabis can make depression, anxiety, and post-traumatic stress disorder worse. So, people with psychiatric problems should probably steer clear of that joint. When the brain is forming in the womb, even the slightest external disruption can cause major problems for the child later on, so pregnant women should not use cannabis. Adolescence is another period of rapid and critical brain development, so it’s little surprise that cannabis use – especially frequent or heavy use – can disrupt academic achievement and lower IQ. Parents and teachers need to help young people make healthy choices about marijuana.
Second, speaking of adolescents, cannabis use raises the risk of developing a psychotic disorder, like schizophrenia, and lowers the age at which psychosis begins. This risk is higher with heavier use as well as use that begins at a younger age. There are also risk factors that make people much more likely to become psychotic after smoking weed, including a family history of schizophrenia, experiencing abuse or trauma in childhood, and growing up in an urban environment. Since psychotic disorders like schizophrenia cause massive disability worldwide, this is an important public health concern.
For older adults without a history of psychiatric problems, moderate marijuana use may be relatively safe for their mental health. However, cannabis smoke has many toxins including carbon monoxide and particulate matter that could cause and exacerbate medical problems. For instance, marijuana has recently been linked to increased risks of stroke and heart failure. Vaporizing or eating pot may be safer options, though we aren’t completely sure.
But aren’t there benefits to cannabis use? Maybe. There is some evidence that marijuana can provide relief for certain, specific medical conditions, such as severe pain from neurological problems, anorexia from HIV/AIDS, or maybe even seizures. And certain compounds in the marijuana plant – like cannabidiol – may help with some psychiatric symptoms.
So what to do? Avoid marijuana entirely? Support Jeff Sessions in his quest to start locking people up again for marijuana possession? On an individual level, the decision whether to use cannabis for medical or recreational purposes is highly personal, but people should at least be informed by scientific evidence rather than media hype, anecdotes, and strong opinions. On a societal level, my opinion is that the War on Drugs has been a complete failure for all drugs, but especially marijuana, causing many more problems than it has purported to solve. Rather than prosecute marijuana users, we should take a public health approach to help people who have a pot problem and work to prevent cannabis use in vulnerable populations like adolescents. And we should pursue rigorous scientific research to find effective ways to prevent harm from marijuana, and search for new medical treatments that could be hiding in this multi-faceted and fascinating plant.
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