Older Adults With Alzheimer's Disease Have Lower Bone Mineral Density Compared to Older Adults Without Dementia: A Systematic Review With Meta-analysis of Observational Studies.

Background and purpose: The literature has associated bone mineral density (BMD) and Alzheimer's disease (AD). The aim of the present systematic review was to investigate BMD in older adults with AD compared with older adults with no dementia.

Methods: Searches were performed in the MEDLINE, EMBASE, CINAHL, and Web of Science databases from inception to May 2022. Observational studies that compared BMD in the populations of interest were included. Methodical quality (risk of bias) was appraised using the Newcastle-Ottawa Scale. Quality of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation approach. Standardized mean differences (SMD) were calculated for meta-analyses.

Results and discussion: Five studies were included, involving a total of 1772 older adults (373 with AD and 1399 with no dementia). A first meta-analysis compared 207 older adults with AD and 1243 with no dementia for BMD in the femoral neck. The results showed lower BMD in the AD groups (SMD =-1.52; 95% CI, -2.61 to -0.42; P = .007, low quality of evidence). A second meta-analysis considering different sites of the body (whole body, trunk, femur, and lumbar spine) also showed lower BMD in older adults with AD compared with the group with no dementia (SMD =-0.98; 95% CI, -1.91 to -0.05; P = .04, low quality of evidence). Newcastle-Ottawa Scale scores ranged from 7 to 9, indicating low risk of bias.

Conclusions: Bone mineral density is lower in older adults with AD than in older adults with no dementia, especially in the femoral neck. These results suggest that older adults with AD may be at greater risk of developing osteopenia and osteoporosis. Current clinical practice guidelines should be amended for screening frequency and methodology for this particular cohort. Further studies are needed to confirm whether older people with AD have lower BMD in other sites of the body.