A new research study has found that regular cannabis use could be linked to changes in the structure of the heart, raising concerns that daily pot consumption could increase the risk of heart attacks or strokes.
British researchers recently conducted one of the first studies to discover whether or not regular cannabis use is linked to alterations in cardiac structure. To determine this, the study authors used cardiovascular magnetic resonance (CMR), a technique they refer to as “the current gold standard” for measuring the chambers of the heart.
The study, recently published in the JACC Cardiovascular Imaging journal, involved a total of 3,407 subjects with an average age of 62. Out of this group, 47 were regular cannabis users, 105 previously used weed regularly, and the remaining 3,255 had either rarely or never gotten high.
The CMR scans revealed that daily weed users had larger left ventricles of the heart, as well as early signs of heart function impairment. The left ventricle is the main pumping chamber of the heart, and prior research has linked this enlargement to an increased risk of strokes or heart attacks. Other heart functions, including the size of the other three heart chambers, and the amount of blood being pumped out of the heart, were not impacted by cannabis use, however.
Although the results of the study are worrying, there are a number of serious limitations to this study. The researchers note that 96 percent of their subjects were white, and out of all these subjects, less than 50 percent used cannabis regularly — making it nearly impossible to determine if the findings would hold true for a more diverse population. The study was also entirely reliant on subjects' self-admission of cannabis, and since pot is illegal in the UK, some regular potheads could have lied and claimed they never touched the stuff.
The prohibition of cannabis also creates another confounding variable. Illegally-produced cannabis is often tainted with molds, toxins, pesticides, heavy metal, solvents, and other contaminants. The present study does not investigate any of the product that was consumed. What if one of these contaminants is responsible for the heart structure changes, rather than cannabis itself? Additionally, researchers failed to take into account other behaviors – like poor diet, lack of exercise, or use of alcohol and other drugs – that might have influenced the health of the regular pot users in the study.
"It is unclear whether the associations observed are due to cannabis use alone or other unmeasured confounding factors,” lead author Dr. Mohammed Khanji, senior clinical lecturer at Queen Mary, University of London in the UK, admitted to Newsweek. "These are early data which included a relatively small group of regular cannabis users and the changes we detected were subtle.”
“Findings should be interpreted with caution, and further research is required to understand the potential pathophysiology, dose-response effects of cannabis use, and long-term implications of regular use on the cardiovascular system,” the study concludes.
However, Dr. Khanji advised that “regular users of cannabis may wish to reduce their intake until further systematic research becomes available which will hopefully provide further insight on the long-term effects of recreational cannabis use."