A common class of drugs used to treat osteoporosis may have an unexpected benefit: lowering the risk of Alzheimer’s disease and other forms of dementia. In a study involving more than 120,000 older adults, researchers at the University of Hong Kong (HKUMed) found that patients taking certain medications to strengthen their bones were significantly less likely to develop dementia.
The medications, known as nitrogen-containing bisphosphonates (NBPs), are widely prescribed to prevent bone loss and fractures. The findings suggest that these established treatments could potentially serve a second purpose by helping protect the aging brain. The research, conducted by scientists in the Department of Pharmacology and Pharmacy at HKUMed’s LKS Faculty of Medicine, was published in Alzheimer’s & Dementia.
More than 55 million people worldwide currently live with dementia, and that number is projected to climb to 139 million by 2050. The World Health Organization has identified dementia as a major global health priority. Although the first medications designed to slow the progression of Alzheimer’s disease and related dementias (ADRD) have recently gained approval, their high costs, limited suitability for some patients, and questions about their effectiveness remain important challenges.
These obstacles have increased interest in finding affordable ways to prevent or delay dementia before symptoms develop. One promising approach is to identify existing medications that might offer benefits beyond the conditions they were originally designed to treat.
The Surprising Connection Between Bone Health and Dementia
Osteoporosis and dementia often affect the same older adults. Osteoporosis causes bones to become weaker and more vulnerable to fractures, while dementia progressively affects memory, thinking, and the ability to carry out everyday activities. The two conditions also share several risk factors, including older age, being female, and low levels of physical activity.
Previous research by the same HKUMed team established that osteoporosis and fractures are independent risk factors for dementia. The researchers also found that people already living with dementia face an increased likelihood of falling and breaking bones.
This relationship raises an intriguing possibility: medications that treat osteoporosis might also help reduce dementia risk.
Among the most commonly prescribed osteoporosis treatments are alendronate and zoledronate, both of which belong to the NBP drug class. These medications work by slowing the breakdown of bone tissue, helping maintain bone strength and reduce the likelihood of fractures.
Scientists have also begun uncovering evidence that some of the biological processes influenced by these drugs may be involved in the development of Alzheimer’s disease and related dementias. This overlap has prompted researchers to investigate whether NBPs might provide benefits for the brain as well as the skeleton.
Study of 120,000 Patients Finds Up to 24% Lower Dementia Risk
To explore this possibility, the HKUMed researchers examined electronic medical records from across Hong Kong, analyzing data from more than 120,000 patients aged 60 and older. All participants had osteoporosis or fragility fractures, which are breaks that can occur after relatively minor injuries because the bones have become weakened.
The records covered the period from 2005 through 2020, allowing the team to investigate how different osteoporosis treatments were associated with dementia risk over time.
The results revealed a notable difference. Patients taking NBPs had a 16% lower risk of developing Alzheimer’s disease and related dementias compared with patients who received no osteoporosis medication.
The association was even stronger when NBP users were compared with patients taking other types of osteoporosis drugs. In that comparison, dementia risk was 24% lower among those receiving NBPs.
Women and patients who had experienced hip fractures appeared to show particularly strong associations between NBP treatment and reduced dementia risk.
The researchers also estimated that treating 48 patients with NBPs over five years could potentially prevent one case of dementia. If future research confirms that the medications directly reduce dementia risk, the implications could be substantial, particularly for older adults who already need treatment for osteoporosis.
Because the findings come from an observational study, they do not establish that the drugs themselves prevent dementia. However, they provide evidence supporting further investigation into whether these medications could help delay or prevent cognitive decline.
Could Existing Osteoporosis Drugs Help Prevent Alzheimer’s?
Professor Cheung Ching-lung, Associate Professor in the Department of Pharmacology and Pharmacy at HKUMed, believes the findings highlight the possibility that a familiar osteoporosis treatment could deliver two important health benefits.
“Our study provides evidence that NBPs may offer dual benefits in strengthening bones and reducing fracture risk, as well as potentially preventing ADRD. Their potential neuroprotective role provides an empirical basis and supports future research on the actual effectiveness of this medication in preventing or delaying cognitive decline associated with ADRD.”
The potential advantage of this approach is that NBPs are already widely available and have an established history of use in treating osteoporosis. Rather than developing an entirely new medication from scratch, researchers could investigate whether these existing treatments offer additional protection for people at elevated risk of dementia.
The findings are particularly relevant as populations around the world grow older and the number of people affected by dementia continues to rise.
“These findings are significant as they demonstrate a potential approach for reducing dementia risk in a vulnerable population using safe and widely available NBPs. In our rapidly aging society, these findings suggest that while waiting for the novel therapies, existing medications can also provide additional protection for high-risk populations,” said Professor Cheung.
Further studies will be needed to determine whether NBPs can directly prevent or delay Alzheimer’s disease and related dementias. Nevertheless, the results suggest that medications already prescribed to protect aging bones may also have an important role to play in protecting brain health.
About the Research Team
The research was led by Professor Cheung Ching-lung of the Department of Pharmacology and Pharmacy at HKUMed. Dr Sing Chor-wing, from the same department, served as the study’s first author.
Additional researchers included Professor Chan Koon-ho, Dr Patrick Chiu Ka-chun, and Professor Kathryn Tan Choon-beng, all from the Department of Medicine in the School of Clinical Medicine at HKUMed.
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