Osteoporosis and sarcopenia in older adults

The percentage of individuals older than 65 years of age is increasing. In 2008, approximately 506 million individuals worldwide were older than 65. This number is expected to double and reach 14% of the world’s population by year 2040. With this increase, a higher number of older men and women are expected to experience deterioration in their bones and muscles leading to osteoporosis and sarcopenia respectively. Therefore, understanding the burden that osteoporosis and sarcopenia represent in older men and women could have major public health implications.\ud \ud We studied the importance of areal and volumetric bone mineral density (vBMD) in fracture risk prediction in older men. We found that low areal BMD (aBMD) and (vBMD) were both associated with multiple sites of fracture. Nonetheless, low vBMD was not found to be a better predictor of major osteoporotic fractures (Hip, spine wrist, shoulder) compared to aBMD, except at the spine. Subsequently, in the same cohort of older men, we found that low appendicular lean mass was positively associated with central and peripheral bone skeletal size, density and strength parameters that have been previously related to fractures. On the other hand, grip strength was only associated with site specific radial strength and geometric parameters. There was no association between leg power and the skeletal size, density and strength of older men after adjusting for appendicular lean mass and grip strength. These findings highlight the more important role of the mechanical load of the muscles on bones, compared to the muscle strength and power. Finally, we were interested in examining whether sarcopenia with or without osteoporosis is associated with an increased risk of non-spine fractures. In this third paper, we demonstrated that men with both sarcopenia and low BMD are at a much higher risk for non-spine fractures compared to men with either one or neither condition. On the other hand, low BMD with or without sarcopenia in older women was associated with an increased risk of fractures, suggesting that low BMD is the driving force of non-spine fractures in older women.\ud \ud Future research should investigate further the crosstalk between muscle and bones. There are currently multiple sarcopenia definitions. Therefore, a consensus on the definition for sarcopenia should be reached, so that diagnostic and therapeutic tools can be developed. Furthermore, dual-energy X-ray absorptiometry (DXA) remains the gold standard diagnostic tool for fracture risk assessment.\u