Rest-activity circadian rhythms and bone mineral density in elderly men

Area of Science:

• Gerontology
• Chronobiology
• Bone Metabolism

Background:

• Disrupted rest-activity circadian rhythm (RAR) is linked to adverse health outcomes.
• Circadian rhythms influence bone turnover, but the link to bone mineral density (aBMD) is under-researched.
• This study investigates RAR and aBMD in older men.

Purpose of the Study:

• To evaluate associations between rest-activity circadian rhythm (RAR) parameters and bone mineral density (aBMD) at the hip and femoral neck in older men.
• To determine if these associations persist after adjusting for confounding factors.

Main Methods:

• Utilized data from the MrOS Sleep ancillary study (n=2412) of ambulatory men aged ≥65 years.
• Assessed aBMD via DXA and RAR using actigraphy over ~5 days, analyzing parameters like pseudo F-statistic and alpha statistic.
• Employed generalized linear models to assess associations between RAR and aBMD/ΔaBMD, adjusting for covariates.

Main Results:

• The pseudo F-statistic (overall rhythmicity) showed initial associations with total hip and femoral neck aBMD and hip ΔaBMD, but these attenuated with multivariate adjustment.
• The alpha statistic (daytime activity ratio) was associated with femoral neck aBMD and ΔaBMD, with significance retained for femoral neck ΔaBMD after adjustment.
• No other RAR variables consistently associated with aBMD or ΔaBMD.

Conclusions:

• Modest associations exist between circadian rhythmicity (pseudo F-statistic) and daytime activity ratio (alpha statistic) with aBMD and bone density changes.
• Most associations were attenuated by lifestyle, BMI, and comorbidity adjustments.
• RAR patterns are not independently associated with hip or femoral neck aBMD in older men, warranting further research.