“Your Bones Are Going To Pot”: Association Between Heavy Marijuana Use And Poor Bone Health

Preclinical studies have suggested that cannabinoid receptors and their ligands play important roles in regulating bone density, bone turnover, and bone cell activity; yet, the effects of marijuana use on bone health are unknown. In this cross-sectional study, researchers compared measures of bone health among individuals with heavy marijuana use (>5000 lifetime smoking episodes, n=144), “moderate” use (<5000 lifetime smoking episodes, n=56), and cigarette smokers (no marijuana use, n=114). Notably, other illicit substance use was common among individuals with heavy marijuana use. Analyses were adjusted for age, sex, BMI, menopausal status, Serum total 25-hydroxyvitamin D concentrations (25[OH]D), serum cross-linked C-telopeptide of type 1 collagen (CTX), N-terminal propeptide of type 1 procollagen concentrations (P1NP), CTX, tobacco smoking, alcohol intake, dietary calcium intake, participation in sports, weight bearing for > 4 hours daily, and other illegal drug use.

• Individuals with heavy marijuana use had lower total hip bone mineral density (mean ± SD Z-score: -0.20 ± 0.9 versus +0.2 ± 0.9), lower spine bone mineral density (-0.5 ± 1.2 versus 0.0 ± 1.2), and lower body mass index (BMI; 26.5 ±6.0 versus 29.0 ±7.0), compared with controls. Fracture rate was also increased in individuals with heavy use (rate ratio, 2.17).
• When compared with controls, measures of bone turnover (CTX and P1NP) were raised in individuals with heavy marijuana use. Compared with controls, 25(OH)D concentrations were reduced in individuals with marijuana use (36.9±26.7 versus 25.3 ±16.8 nmol/L).
• Multiple regression analysis revealed that heavy marijuana use was an independent predictor of spine bone mineral density and total hip bone mineral density. Mediation analysis suggested that the effect of marijuana on spine bone mineral density was indirect and mediated through low BMI and the effect on hip bone mineral density was moderated by the use of other illicit substances.

Comments: Although cause and effect relationships cannot be inferred from the results of this observational study, these data suggest that heavy marijuana use is associated with poorer measures of bone health and that other illicit substance use may contribute.

Jeanette M. Tetrault, MD

Reference: Sophocleous A, Robertson R, Ferreira NB, et al. Heavy cannabis use is associated with low bone mineral density and an increased risk of fractures. Am J Med. 2017;130(2):214–221.