Adam’s Journal
Here’s a great question we received when we spoke at the Kiwanis Club of Downtown Oklahoma City (thank you for the invitation!) earlier this month:
We have medical marijuana in Oklahoma, and we may be soon voting – again – on recreational marijuana. As an employer, I am concerned about the health of my employees who use marijuana. What do we know about the short- and long-term effects of marijuana use?
Dr. Scofield Prescribes
Most people consider marijuana safe. However, as its use is spreading, a different picture is beginning to emerge.
Long-term studies of marijuana use are still few and far between. This is both because widespread usage of the drug has only become legal over the past decade, and federal laws still make it extremely difficult to conduct research with marijuana.
In Sweden, scientists have looked at the impact of marijuana use in military draftees over a 40-year period. The researchers followed almost 50,000 men from 1969-70 (when they were drafted at the ages of 18-20) until 2009.
The scientists found that those who were “heavy” marijuana smokers – defined as more than 50 times over their lives – had more than twice the risk of developing lung cancer, even when adjusted for tobacco use and other factors that might elevate disease risk.
Another study using this same group found that those who used marijuana showed an elevated probability of developing schizophrenia and other psychoses. Once again, this increased risk held true even when scientists incorporated other factors such as personality traits or use of other psychoactive drugs.
That work has since been reinforced by multiple studies. A 2023 Danish analysis of nearly 7 million people found that up to 30% of schizophrenia cases among young men were linked to cannabis use disorder. And earlier this year, a study of more than 13 million Canadians found the same association.
Research published in June in the journal Heart also found that marijuana use was associated with a twofold increase in the risk of death from cardiovascular disease.
In addition, there is a growing body of evidence that marijuana can affect brain development in young people. A Johns Hopkins University study using functional magnetic resonance imaging found that cannabis use during adolescence was linked to alterations in brain function during cognitive tasks. The scientists noted that these changes appeared in portions of the brain related to executive functioning and emotional control.
In a different study, scientists also determined that marijuana use is associated with higher levels of suicidal ideation in teens.
More anecdotally – meaning that we’ve not yet conducted longer-term studies – physicians (me included) are seeing surging numbers of people experiencing significant health problems related to regular marijuana use. These include psychosis, other psychiatric disorders and cannabinoid hyperemesis syndrome (CHS).
Until a few years ago, CHS was virtually unknown. But now the condition, chronic nausea and vomiting brought on by regular marijuana use, is a commonplace diagnosis in emergency rooms.
For people experiencing CHS, a long, hot shower or bath can bring temporary relief. But the only known cure is one that CHS patients least want to hear: give up pot.
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Dr. Hal Scofield is a physician-scientist at the Oklahoma Medical Research Foundation, and he also serves as Associate Chief of Staff for Research at the Oklahoma City VA Medical Center. Adam Cohen is OMRF’s senior vice president and general counsel. Send your health questions to contact@omrf.org.
