A Specific Gene May Explain How Cannabis Lowers Eye Pressure | Research

The takeaway

Cannabis appears to reduce eye pressure through the GAS7 gene in humans, while the CB1 and GPR18 receptors that mediate this effect in mice do not seem to be involved in people.

Glaucoma researchers, geneticists, people interested in cannabis and eye health

37,046 subjects analyzed

What the researchers found

Carriers of the GAS7 gene variant (rs9913911 minor allele G) showed lower intraocular pressure with increased cannabis use (P<0.001). The CDKN2B-AS1 glaucoma gene showed no such interaction. CB1 and GPR18, which mediate cannabis IOP reduction in mice, showed no significant relationship in humans.

Why it matters

Understanding exactly how cannabis lowers eye pressure at the genetic level could lead to targeted treatments that capture the benefit without requiring cannabis use itself.

The numbers in context

37,046 subjects; GAS7 interaction P<0.001; CDKN2B-AS1 interaction P=0.138 (not significant); CB1 and GPR18 interactions not significant

How the study worked

Analysis of 37,046 UK Biobank subjects examining the interaction between cannabis use, genotype variants in glaucoma-associated genes (GAS7 and CDKN2B-AS1), and intraocular pressure using univariate ANOVA.

What this study cannot tell us

Observational design. Genetic associations do not prove mechanism. UK Biobank population may not generalize globally. Cannabis use was self-reported.

How to read the evidence

Large cohort with genetic analysis, but observational design and the complexity of gene-environment interactions warrant caution.

When this study was published

Published in 2022

The bigger picture

Cannabis has been known to lower eye pressure since the 1970s, but the mechanism has remained unclear. This study narrows the target to a specific gene, though the authors note that disadvantages of cannabis-based treatments now outweigh the advantages.

Questions still open

Could GAS7-targeted therapies replicate cannabis's IOP-lowering effect? Why do the receptors involved differ between mice and humans?

Common questions

How does cannabis lower eye pressure?

This study suggests cannabis acts through the GAS7 gene (chromosome 17) to reduce intraocular pressure in humans, which is different from the CB1 receptor mechanism found in mice.

Should cannabis be used to treat glaucoma?

The study authors concluded that while cannabis does lower eye pressure through GAS7, its "disadvantages outweigh advantages" compared to modern glaucoma treatments available today.

Read the original research

Cannabis, Intraocular Pressure, and the Growth Arrest-Specific 7 (GAS7) Gene: A Retrospective Analysis.

Cureus, 14(4), e23919

View on PubMed ↗Publisher’s paper ↗

Citation

Lehrer, Steven; Rheinstein, Peter H. (2022). Cannabis, Intraocular Pressure, and the Growth Arrest-Specific 7 (GAS7) Gene: A Retrospective Analysis.. Cureus, 14(4), e23919. https://doi.org/10.7759/cureus.23919