Bone Loss and Osteoporosis are Associated with Conversion from Mild Cognitive Impairment to Alzheimer's Disease

Objective: The aim of this study was to analyze the relationship between low bone mineral density (BMD) and conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD) dementia in a Chinese cohort. Methods: Men and women (n=946) aged 60-75 underwent a dual X-ray absorptiometry (DXA) study of the lumbar spine and hip and were followed annually for 5 years. Their cognitive and functional status were assessed using the Chinese version of the Mini-Mental State Examination (MMSE) and an assessment of the instrumental activities of daily living (ADL). Results: There was a positive relationship between osteoporosis and a decline in cognition and function (P<0.001) based on MMSE and ADL scores. The subjects with BMD values in the lowest quartile had a 2-fold increased risk of AD conversion compared with the controls. These results suggest that severe BMD loss is associated with an increased risk of AD conversion in both women and men. Conclusions: Osteoporosis was associated with an increased risk of incident AD dementia. Additionally, low BMD at baseline was associated with an increased risk of AD in both women and men.