Scientists have been looking at the connection between our muscles and our dementia risk for decades. 

A recent study, for instance, found that the size of our temporalis muscle ― which is a good way to tell how much sarcopenia, or muscle mass loss, has affected a person ― seems to be linked to our dementia risk. 

Additionally, how long you can stand on one leg as you age appears to be associated with your likelihood of developing Alzheimer’s; signs of frailty might show increased odds nine years ahead of diagnosis.

But new research says that the “biological age” of our organs might be able to tell us how large the prospect of dementia might loom in our bodies too.

How do organ ages affect dementia risk?

The study, published by The Lancet Digital Health, looked at 6,235 adults from the Whitehall II study of UK government employees. 

They looked at their health data at the start of the study, and then again 20 years later. 

Those health metrics involved looking at the protein in the participant’s blood in a process called proteomic analysis.

That way, they found the “biological age” of their brain, arteries, immune system, heart, kidneys, intestine, liver, lung, and pancreas ― this shows how the cells in those organs are faring, despite the chronological age of the participant. 

If the participants had accelerated ageing in an organ, they were more likely to develop a condition associated with it ― for instance, those with a higher heart age were more likely to develop coronary conditions, while those whose brain age was higher than it should be were more likely to develop dementia.

Interestingly, though, people who had one organ that was ageing faster than is ideal tended to experience accelerated ageing in their other organs too.

“A blood test determining how much [organs have] aged could predict the risk of conditions like lung cancer and heart disease decades later,” University College London (UCL), whose scientists were involved in the study, said.

The highest risk of dementia was found among people with ageing immune systems.

Why does that work, and what can I do about it?

Speaking to UCL, Dr Tony Wyss-Coray explained: “Organs function in close coordination, so accelerated ageing in one organ can impair the function of others, which may explain why people with a rapidly ageing organ were particularly prone to experiencing multiple age-related diseases across different organs.”

In some ways, conventional dementia prevention risk has reflected the newly-bolstered advice; Alzheimer’s experts have long maintained that what’s good for the heart is good for the brain, for instance.

Dr Kivimaki, who was also involved in the study, told UCL: “We hope our findings could contribute to new ways of helping people stay healthy for longer as they age.

“Blood tests may advise whether a person needs to take better care of a particular organ, and potentially provide an early-warning signal that they may be at risk of a particular disease.”

Until then, sticking to research-backed advice (not smoking, not drinking too much, exercising, eating well, staying social, and sleeping enough) is bound to give your entire organ system its best shot.