Low bone density and osteoporosis among older adults with Alzheimer's disease, vascular dementia, and mixed dementia: A Cross-sectional Study With Prospective Enrollment

Abstract

Objectives: This study aims to examine bone mineral density (BMD) and osteoporosis in older adults with dementia compared to those with a normal cognitive status and to evaluate the type, severity, and duration of dementia.

Patients and methods: Between May 2013 and May 2017, a total of 363 participants aged ≥65 years (136 males, 227 females; mean age 78.4±5.4 years; range 66 to 99 years) with and without Alzheimer's disease (AD), vascular dementia (VaD), or mixed dementia (AD-VaD) were included in this single-center, prospective, cross-sectional study. The dementia group included 93 patients with dementia and the control group included 270 age- and sex-matched healthy individuals. We used dual-energy X-ray absorptiometry (DXA) to measure BMD of the lumbar spine, total hip, and femoral neck.

Results: Controlled for age and sex, demented and non-demented participants had a similar BMD (g/cm²) at lumbar spine [F (1, 358):0.83, p=363], but lower BMD values of total hip [F (1, 359):10.26, p=0.001] and femoral neck [F (1, 359):15.21, p<0.001] in the patients with dementia. Adjusted percentage of osteoporosis and low bone mass based on total hip and femoral neck T-scores were also significantly higher in the patient group. The mean BMD values, frequency of osteoporosis, and low bone mass did not significantly differ according to the subtype of dementia, sex, and disease duration or severity.

Conclusion: Our study results show that demented elders have a lower BMD and higher frequency of osteoporosis at the hip, but not at the lumbar spine, irrespective of sex and type of dementia. Based on these results, we can speculate that not only AD, but also VaD and AD-VaD may be associated with bone loss at the hip.

Keywords: Alzheimer’s disease; bone disease; metabolic; osteoporosis; vascular.