A new study suggests that people with low bone density may have a greater risk of developing dementia than those with higher bone density.
This is not to say there is proof that low bone density causes dementia, only that the data show an association.
Elderly people frequently have both low bone density and dementia at the same time, especially since bone loss is frequently accelerated by inactivity and poor nutrition during dementia.
“However, little is known about bone loss that occurs in the period leading up to dementia. Our study found that bone loss indeed already occurs before dementia and thus is linked to a higher risk of dementia,”
said study author Mohammad Arfan Ikram, MD, PhD, of Erasmus University Medical Center.
42% More Likely
The study included 3,651 Dutch people with an average age of 72 who did not have dementia at the start of the study. 688 people, or 19%, developed dementia over an average of 11 years.
Researchers examined X-rays to determine bone density. Participants were interviewed every four to five years and had physical exams such as bone scans and dementia tests.
Within 10 years, 90 of the 1,211 people with the lowest total body bone density developed dementia, compared to 57 of the 1,211 people with the highest bone density.
After controlling for age, gender, education, other illnesses and medication use, and a family history of dementia, researchers discovered that people with the lowest total body bone density were 42% more likely to develop dementia than those in the highest group within 10 years.
More Research Needed
Previous studies have found that factors such as diet and exercise may have different effects on bones as well as the risk of dementia.
“Our research has found a link between bone loss and dementia, but further studies are needed to better understand this connection between bone density and memory loss. It’s possible that bone loss may occur already in the earliest phases of dementia, years before any clinical symptoms manifest themselves. If that were the case, bone loss could be an indicator of risk for dementia and people with bone loss could be targeted for screening and improved care,”
The study’s limitation is that participants were primarily of European origin and aged 70 or older at the start of the study, so the findings may differ in different races, ethnicities, and younger age groups.
Background & Objective: Low bone mineral density and dementia commonly co-occur in the elderly, with bone loss accelerating in dementia patients due to physical inactivity and poor nutrition. However, uncertainty persists over the extent to which bone loss already exists prior to the onset of dementia. Therefore, we investigated how dementia risk was affected by bone mineral density at various skeletal regions in community-dwelling older adults.
Methods: In a prospective population-based cohort study, bone mineral density at the femoral neck, lumbar spine, and total body and the trabecular bone score were obtained using dual-energy X-ray absorptiometry (DXA) in 3,651 participants free from dementia between 2002-2005. Persons at risk of dementia were followed up until 1 January 2020. For analyses of the association between bone mineral density at baseline and the risk of incident dementia, we used Cox proportional-hazards regression analyses, adjusting for age, sex, educational attainment, physical activity, smoking status, body mass index, systolic blood pressure, diastolic blood pressure, cholesterol level, high-density lipoprotein cholesterol, history of comorbidities (stroke and diabetes mellitus), and APOE genotype.
Results: Among the 3,651 participants (median age 72.3±10.0 years, 57.9% women), 688 (18.8%) developed incident dementia during a median of 11.1 years, of whom 528 (76.7%) developed Alzheimer’s disease. During the whole follow-up, participants with lower bone mineral density at the femoral neck (per SD decrease) were more likely to develop all-cause dementia (Hazard ratio [HR] total follow-up: 1.12, 95% Confidential interval [CI]: 1.02-1.23) and Alzheimer’s disease (HR total follow-up: 1.14, 95% CI: 1.02-1.28). Within the first ten years following baseline, the risk of dementia was greatest for groups with the lowest tertile of bone mineral density (femoral neck bone mineral density, HR0-10years 2.03; 95% CI, 1.39–2.96; total body bone mineral density, HR0-10years 1.42; 95% CI, 1.01–2.02; trabecular bone score, HR0-10years 1.59; 95% CI, 1.11–2.28).
Conclusions: In conclusion, participants with low femoral neck and total body bone mineral density and low trabecular bone score were more likely to develop dementia. Further studies should focus on the predictive ability of bone mineral density for dementia.
- Tian Xiao, Samuel Ghatan, Sanne S. Mooldijk, Katerina Trajanoska, Ling Oei, M. Medina Gomez, M. Kamran Ikram, FernandoRivadeneira, M. Arfan Ikram. Association of Bone Mineral Density and Dementia: The Rotterdam Study. Neurology Mar 2023, 10.1212/WNL.0000000000207220; DOI:10.1212/WNL.0000000000207220