A person’s real risk of dementia may depend not only on how old they are, but also on how old their body appears biologically.
That is the conclusion of a major new study led by researchers at King’s College London, which found that people whose bodies are aging faster internally face a much greater risk of developing dementia.
The findings were published in the journal Alzheimer’s & Dementia and are based on health data from more than 220,000 participants in the UK Biobank project.
Scientists say the research could eventually lead to simple blood tests that identify people at high risk of dementia years before symptoms appear.
Dementia is one of the biggest health challenges facing aging populations worldwide.
The condition affects memory, thinking, language, and the ability to carry out everyday activities. Alzheimer’s disease is the most common form, but there are several other types, including vascular dementia, which is linked to blood vessel damage in the brain.
Experts estimate that nearly one million people in the UK currently live with dementia, and that number is expected to rise dramatically in the coming decades.
While older age is the strongest known risk factor, scientists increasingly believe that dementia is influenced by many different biological processes.
Importantly, researchers estimate that up to 45% of dementia cases may potentially be delayed or prevented by reducing risk factors such as smoking, obesity, inactivity, poor diet, high blood pressure, diabetes, and social isolation.
The new study explored whether biological aging itself could help predict dementia risk.
Biological age is different from chronological age. Chronological age simply measures how many years someone has lived. Biological age attempts to measure how “old” the body appears internally.
Some people may have healthier organs, blood vessels, and metabolism than others of the same age.
To estimate biological age, the researchers studied metabolites in blood samples.
Metabolites are tiny molecules created during normal body processes such as producing energy from food.
Scientists know that patterns of metabolites change as people age and may reflect how healthy the body is overall.
The research team used these metabolite patterns to calculate something known as a metabolomic aging clock.
This type of clock estimates whether a person’s body appears biologically older or younger than expected.
Researchers then calculated the difference between biological age and chronological age, a measurement called “MileAge delta.”
A higher MileAge delta meant the body appeared older than expected for the person’s age.
The study followed participants over time to see who later developed dementia.
Nearly 4,000 participants eventually developed some form of dementia.
The results showed that people with significantly accelerated biological aging had much higher risks of dementia.
Overall, participants whose biological age was notably older than their actual age had around a 20% greater risk of developing dementia.
The connection was even stronger for vascular dementia, where the risk increase reached about 60%.
The researchers also examined genetic risk factors.
One of the strongest known genetic risks for Alzheimer’s disease is carrying the APOE ε4 gene variant.
People who inherited two copies of this gene and also showed advanced biological aging faced extremely high risk.
According to the study, these individuals were up to 10 times more likely to develop dementia than the average participant.
Researchers found that genetic risk and biological aging appeared to operate mostly independently.
This means that both inherited genes and general body aging may separately contribute to dementia development.
Lead researcher Dr. Julian Mutz explained that the findings may eventually help doctors identify high-risk individuals before memory problems begin.
The researchers believe blood-based aging clocks may one day become valuable tools for early screening and prevention.
One reason the findings are encouraging is that biological aging may potentially be influenced by lifestyle choices and medical care.
Unlike genes, which cannot be changed, biological aging may respond to healthier behaviors such as exercise, healthy eating, good sleep, stress reduction, and controlling blood pressure and diabetes.
The study also supports growing scientific interest in minimally invasive blood tests for brain diseases.
Current methods for detecting dementia risk often rely on expensive scans or more invasive procedures.
Blood tests could make large-scale screening easier and more affordable in the future.
Still, the researchers emphasize that this study only identified associations and cannot prove that faster biological aging directly causes dementia.
More research will be needed to determine whether slowing biological aging can actually lower dementia risk.
Experts also say the metabolomic aging clock technology is still developing and is not yet ready for widespread clinical use.
Even so, the findings provide another important clue about how dementia develops and why some people may face much higher risk than others.
In the future, doctors may use both genetic information and biological aging measurements together to better predict who is most likely to develop dementia and who may benefit most from prevention efforts.
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The study was published in Alzheimer’s & Dementia.
Source: King’s College London.
