Bone metabolic biomarkers and bone mineral density in male patients with early-stage Alzheimer's disease.

Purpose: Alzheimer's disease (AD), osteoporosis, and osteopenia are the most common diseases in older individuals and share some similar pathophysiological processes of degeneration. The aim of this study is to investigate the association between bone metabolic biomarkers, bone mineral density (BMD), and early-stage AD in men.

Methods: Forty-two male early-stage AD patients and 40 age-matched healthy older volunteers were enrolled. Serum calcium, osteocalcin, 1,25(OH)D, urine deoxypyridinoline/creatinine (DPD/Cr) ratio, urine calcium/creatinine (Ca/Cr) ratio, and BMD were measured. The correlation between early-stage AD and bone quality was evaluated.

Results: The urine DPD/Cr, urine Ca/Cr, and serum osteocalcin levels in the early-stage AD patients were significantly higher than those in the healthy control (HC) group (P < 0.05). The BMD data showed that the cortical and total BMD at 38% of the tibial length in the early-stage AD patients were lower than those in the HC group (P < 0.05). Furthermore, there was a negative correlation between the Montreal Cognitive Assessment score and serum osteocalcin or urine DPD/Cr levels. Abnormal urine DPD/Cr, urine Ca/Cr, and cortical BMD levels were independent risk factors in male patients with early-stage AD.

Conclusion: Bone metabolic biomarkers and BMD are closely associated with early-stage AD in male patients. Our data indicated that the measurement of bone metabolic biomarkers and BMD may provide an alternative approach for screening AD patients at the early stage.