Smoking marijuana may slow inflammation associated with the onset of  age-related macular degeneration (AMD), according to research published in Journal Français d’Ophtalmologie. However, cannabis smokers who do develop AMD are diagnosed at significantly younger ages than those who do not use the drug, according to the study. 

Researchers enrolled 419 participants (mean age 56±8 years, 54% women) in a multicenter analysis between 2006 and 2010 to determine the effect of marijuana use on AMD diagnosis. They recorded patient cannabis use habits and longitudinally followed participants for changes in health events. 

The team noted that frequent marijuana use (more than 100 times) was associated with a significantly decreased risk in AMD compared with never using marijuana. Using marijuana every day also correlated with a decreased AMD risk compared with using the drug less than once per month. In an apparent contradiction, the investigators also note that study participants who smoked cannabis frequently and did develop AMD did so at an earlier age (8 years younger) than those who did not smoke cannabis. 


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Researchers highlight these seemingly contradictory findings stating that marijuana use can slow the inflammation process associated with AMD.  However, “at the same time, blood vessels in the choriocapillaris below Bruch’s membrane become more sparse with age. This phenomenon is believed to be a starting point for AMD. Marijuana can accelerate the loss of blood vessels due to its anti-angiogenic properties. Therefore, marijuana use might cause AMD to develop sooner in younger people.”

Study limitations include an overrepresentation of individuals reporting as British White.

Reference

Lehrer S, Rheinstein PH. Cannabis smoking and age-related macular degeneration in the UK Biobank cohort. J Fr Ophthalmol. Published online June 23, 2022. doi:10.1016/j.jfo.2022.01.004