Cannabis Use Linked to Risk of Osteoporosis

A May 23, 2005 article in the U.K. Guardian reported on the study "Regulation Of Bone Mass, Bone Loss And Osteoclast Activity By Cannabinoid Receptors" published in the journal Nature Medicine by researchers Stuart H. Ralston, et. al.:

"Excessive use of cannabis can lead to brittle bones, new research suggests. Scientists have found that molecules on the surface of bone cells are targeted by cannabis chemicals. They discovered that drugs which block these cannabinoid receptors may prevent bone loss.

But the flip-side to the research is that smoking cannabis is likely to promote osteoporosis.

Professor Stuart Ralston, who led the research at the University of Aberdeen, said: 'We hadn't studied cannabis users, but the work we've done would suggest that if you use a lot of cannabis it could stimulate bone-absorbing cells, and that would be bad.'

Receptors are molecules that act like a 'lock' into which other molecules fit. Molecules that affect cells are activated when they bind to specific receptors....

Prof Ralston, one of Britain's leading osteoporosis experts, said he saw many patients with bone loss who used drugs of various types. But he pointed out that diet, smoking, and other lifestyle issues may also be involved. 'If using cannabis is one of the factors involved, we ought to know about it,' he added."
May 23, 20/05 U.K. Guardian

The article's abstract (published online: 22 May 2005; doi:10.1038/nm1255) from the peer-reviewed jounral Nature Medicine follows:

"Accelerated osteoclastic bone resorption has a central role in the pathogenesis of osteoporosis and other bone diseases. Identifying the molecular pathways that regulate osteoclast activity provides a key to understanding the causes of these diseases and to the development of new treatments.

Here we show that mice with inactivation of cannabinoid type 1 (CB1) receptors have increased bone mass and are protected from ovariectomy-induced bone loss.

Pharmacological antagonists of CB1 and CB2 receptors prevented ovariectomy-induced bone loss in vivo and caused osteoclast inhibition in vitro by promoting osteoclast apoptosis and inhibiting production of several osteoclast survival factors.

These studies show that the CB1 receptor has a role in the regulation of bone mass and ovariectomy-induced bone loss and that CB1- and CB2-selective cannabinoid receptor antagonists are a new class of osteoclast inhibitors that may be of value in the treatment of osteoporosis and other bone diseases."
May 2005 Nature Medicine