Low bone mineral density associated with dementia risk

By Melanie Hinze

There may be a predictive association between bone mineral density (BMD) and dementia, according to new research published in Neurology.

A team of Dutch researchers found that people with low femoral neck and total body BMD and low trabecular bone score were at increased risk of developing dementia, and that this association was strongest in the first 10 years of follow up.

The Rotterdam Study, a prospective population-based cohort study, a used dual-energy x-ray absorptiometry (DXA) to obtain BMD measurements for the femoral neck, lumbar spine and total body, as well as the trabecular bone score, for 3651 participants without dementia between 2002 and 2005. The median age of the participants was 72.3±10 years and 57.9% were women.

In total, 18.8% of participants developed incident dementia over a median follow up of 11.1 years. Among these participants, 76.7% developed Alzheimer’s disease.

The researchers found that throughout the duration of follow up, lower BMD at the femoral neck, but not at other bone sites, was related to a 12% higher risk of developing all-cause dementia and a 14% higher risk of developing Alzheimer’s disease.

Within the first 10 years of follow up, the risk of dementia was greatest for groups with the lowest BMD, including femoral neck and total body BMD and trabecular bone score.

Professor Ralph Martins, Professor of Neurobiology at Macquarie University, Sydney, and Foundation Chair of Aging and Alzheimer’s disease at Edith Cowan University, Perth, said this prospective study built on previous findings that low BMD was associated with dementia.

‘Furthermore, the authors provide convincing evidence to demonstrate for the first time that low BMD is predictive of Alzheimer’s and dementia.’

Professor Martins said these finding may allow for early detection and potentially effective therapeutic approaches to delay or even stop the onset of Alzheimer’s disease and dementia.

Professor Kaaren Anstey, an ARC Laureate Fellow and Scientia Professor at UNSW Sydney, and Senior Principal Research Scientist at NeuroScience Research Australia (NeuRA), Sydney, also commented on this research, saying that although the association between BMD and dementia seemed robust, it should also be noted that it may be difficult to know the causal direction of these findings.

‘There are many changes in the health status of people who develop dementia, and it may be that we are seeing a general dysregulation and decline across multiple body systems and that people who end up developing dementia during the 11 years of follow up are ageing at a faster rate,’ she told Medicine Today.

‘Or it may be that there are factors that result from preclinical dementia which impact bone density,’ she added. ‘For example, older people with preclinical dementia may become less physically active and change their diet.’

Nevertheless, Professor Anstey said that addressing some of the overall lifestyle and medical factors that cause a reduction in BMD may also have benefits for reducing the risk of dementia.

 Neurology 2023; doi: 10.1212/WNL.0000000000207220.