New Study Finds Marijuana Use May Damage the Structure of the Heart

The researchers analyzed the heart scans of 3,407 people.
Loukia Papadopoulos

Just when it looked like marijuana was about to get legalized in many places as a result of being deemed harmless, a new study emerged that may change all that. A team of researchers from the United Kingdom found that the substance has some pretty negative effects on one crucial organ: the heart.


3,407 heart scans

The researchers analyzed the heart scans of 3,407 people with an average age of 62 collected as part of the UK Biobank study. The scans were taken from people without heart disease.

Most of these people had never smoked marijuana, however 47 were regular marijuana users, and another 105 had used cannabis regularly five or more years prior. 

The study found that regular marijuana users showed an enlarged left ventricle as well as early signs of impaired heart function. “We believe this is the first study to systematically report changes in heart structure and function associated with recreational cannabis using cardiac MRI, which is a very sensitive imaging tool and the current reference standard for assessing cardiac chambers," said lead author Dr Mohammed Khanji, Senior Clinical Lecturer at Queen Mary.

"The World Health Organization has warned about the potentially harmful health effects of non-medical cannabis use and called for more research specifically around the cardiac impact.”

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The study, however, had several limitations. The participants were 96% white, they self-reported their cannabis habits, the sample of marijuana users was quite small, and the changes detected were subtle.

Still, the researchers believe their results were important enough to warrant further studies especially considering the drug may soon be legalized in more and more places.

“We urgently need systematic research to identify the long-term implications of regular consumption of cannabis on the heart and blood vessels,” Khanji said. “This would allow health professionals and policymakers to improve advice to patients and the wider public.”

The study was published in the journal JACC Cardiovascular Imaging. 

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