Heavy marijuana smoking linked to COPD and faster lung decline in older adults
Heavy marijuana smokers (more than 20 joint-years) had 2.45 times the risk of COPD, and those who also smoked tobacco experienced faster lung function decline than tobacco alone.
Quick Facts
What This Study Found
Among heavy marijuana users, the risk of COPD was significantly increased (adjusted OR 2.45, 95% CI 1.55-3.88). Heavy marijuana smokers who also smoked tobacco experienced faster FEV1 decline of 29.5 mL/year compared to never-smokers, while heavy tobacco smokers alone declined 21.1 mL/year.
Key Numbers
1,285 participants aged 40+. ~20% had been or were current marijuana smokers. 83% of marijuana smokers also smoked tobacco. Heavy use defined as >20 joint-years. COPD risk: adjusted OR 2.45 (95% CI 1.55-3.88). FEV1 decline: 29.5 mL/year for heavy dual smokers vs. 21.1 mL/year for heavy tobacco only.
How They Did This
Longitudinal analysis of 1,285 males and females aged 40+ from the Canadian Cohort of Obstructive Lung Disease study, with spirometry performed before and after bronchodilator on multiple occasions. Mixed effects regression models adjusted for age, sex, and BMI.
Why This Research Matters
Most marijuana-lung studies focus on younger populations. This study specifically examines older adults, where cumulative exposure effects become more apparent and COPD risk is most relevant.
The Bigger Picture
As the first generation of long-term cannabis users reaches older age, understanding cumulative respiratory effects becomes increasingly important for clinical guidance.
What This Study Doesn't Tell Us
Self-reported marijuana use. 83% of marijuana smokers also used tobacco, making it difficult to isolate marijuana-specific effects. Observational design cannot establish causation.
Questions This Raises
- ?Do vaporized or edible forms of cannabis avoid these respiratory risks?
- ?Is there a threshold of joint-years below which COPD risk is not elevated?
Trust & Context
- Key Stat:
- 2.45x COPD risk for heavy marijuana smokers
- Evidence Grade:
- Large longitudinal cohort with objective spirometry measurements, though confounded by concurrent tobacco use.
- Study Age:
- 2019 study.
- Original Title:
- The effects of marijuana smoking on lung function in older people.
- Published In:
- The European respiratory journal, 54(6) (2019)
- Authors:
- Tan, Wan C(2), Bourbeau, Jean(3), Aaron, Shawn D, Hogg, James C, Maltais, François, Hernandez, Paul, Marciniuk, Darcy D, Chapman, Kenneth R, To, Teresa, FitzGerald, J Mark, Walker, Brandie L, Road, Jeremy, Zheng, Liyun, Zhou, Guohai, Yau, Trevor, Benedetti, Andrea, O'Donnell, Denis, Sin, Don D
- Database ID:
- RTHC-02313
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Does marijuana smoking cause COPD?
This observational study found heavy marijuana smokers had 2.45 times the COPD risk, but most also smoked tobacco, making it difficult to attribute the risk to marijuana alone.
How does marijuana affect lung decline compared to tobacco?
Heavy dual smokers (marijuana plus tobacco) lost lung function at 29.5 mL/year compared to 21.1 mL/year for heavy tobacco smokers alone, suggesting an additive effect.
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Cite This Study
https://rethinkthc.com/research/RTHC-02313APA
Tan, Wan C; Bourbeau, Jean; Aaron, Shawn D; Hogg, James C; Maltais, François; Hernandez, Paul; Marciniuk, Darcy D; Chapman, Kenneth R; To, Teresa; FitzGerald, J Mark; Walker, Brandie L; Road, Jeremy; Zheng, Liyun; Zhou, Guohai; Yau, Trevor; Benedetti, Andrea; O'Donnell, Denis; Sin, Don D. (2019). The effects of marijuana smoking on lung function in older people.. The European respiratory journal, 54(6). https://doi.org/10.1183/13993003.00826-2019
MLA
Tan, Wan C, et al. "The effects of marijuana smoking on lung function in older people.." The European respiratory journal, 2019. https://doi.org/10.1183/13993003.00826-2019
RethinkTHC
RethinkTHC Research Database. "The effects of marijuana smoking on lung function in older p..." RTHC-02313. Retrieved from https://rethinkthc.com/research/tan-2019-the-effects-of-marijuana
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.