Can your biological age predict Alzheimer's risk?

by Sarah Knapton for The Telegraph:

A blood test which shows how well people are ageing can predict the onset of diseases like Alzheimer’s, researchers believe.

Scientists have identified a set of genes which must be functioning properly for ‘healthy ageing’ in 65-year-olds.

How well those genes are working can be added up into a ‘healthy age gene score.’ The lower the score the more likely disease is present or likely to develop.

Given that early intervention is important in Alzheimer’s, scientsts at Kings College London say the test will help doctors decide which middle-aged subjects could be offered preventative therapies before the first symptoms of dementia begin to appear.

Although there are no drugs which stop dementia, new treatments which slow down the disease if given early enough, are showing early promise in trials.

It is also the first practical and accurate test for the rate at which individual bodies are ageing.

“Most people accept that all 60 year olds are not the same, but there has been no reliable test for underlying 'biological age',” said lead author James Timmons, from King’s College London.

“Our discovery provides the first robust molecular ‘signature’ of biological age in humans and should be able to transform the way that 'age' is used to make medical decisions.

“This includes identifying those more likely to be at risk of Alzheimer’s, as catching those at 'early' risk is key to evaluating potential treatments.

“This also provides strong evidence that dementia in humans could be called a type of ‘accelerated ageing’.”

The seven-year collaborative study at King’s College London, Karolinska Institutet in Sweden and Duke University in the USA, used a process called RNA-profiling to measure and compare gene expression in thousands of human tissue samples.

Scientists compared tissue from 25-year-olds to that of 65-years-olds and identified a pattern of activation in 150 genes which needed to be in place for healthy ageing.

The researchers found big differences in the age scores of people born within a year of each other, suggesting that ‘biological age’ differs considerably from ‘chronological age.’

Those with the worst ‘health age gene score’ were far more likely to suffer from mental decline and poor health such as loss of renal function.

In particular, they demonstrated that patients diagnosed with Alzheimer’s Disease had much lower scores, suggesting significant association with the disease.

There are 850,000 people currently suffering from dementia in the UK, with Alzheimer's disease being the most common type. The disease kills at least 60,000 people each year.

Dr Neha Issar-Brown, programme manager for population health sciences at the Medical Research Council, which funded the research added: “Whilst it is natural for our bodies and brains to slow down as we age, premature ageing and the more severe loss of physical and cognitive function can have devastating consequences for the individual and their families, as well as impact more widely upon society and the economy.

“This new test holds great potential as with further research, it may help improve the development and evaluation of treatments that prolong good health in older age.”

Charities said any test which could spot Alzheimer’s early was critical to stopping the disease.

Dr Doug Brown, Director of Research at Alzheimer’s Society said: “Given the need for early intervention, many of the current drugs in development for Alzheimer’s are being tested in the earliest stages of the disease, sometimes even before symptoms begin.

“With further development this research could help in our quest to find new treatments for the condition, by identifying people who are more likely to develop Alzheimer’s disease so that they can participate in clinical trials.”

Dr Eric Karran, Director of Research, Alzheimer’s Research UK, added: “This study suggests a way to measure a person’s ‘biological age’ and could reveal insights into the ageing process and why some people are more susceptible to age-related health conditions.

“There is much interest in developing a blood test for diseases like Alzheimer’s but such a test would need rigorously validating to show it was accurate and sensitive before it could be used in the clinic.”

The research was published in the journal Genome Biology.

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