September 7, 2015

expert reaction to study reporting a potential molecular test for biological ageing

Publishing in the journal Genome Biology, a group of scientists has described their identification of an “RNA signature” from a person’s blood sample, which they report can be used to predict future health.

Dr Doug Brown, Director of Research, 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.

“Previous studies have identified sets of markers in the blood of people with Alzheimer’s but they have not yet been accurate enough to be used regularly in research or in the clinic. This study takes a novel approach, using healthy older people to identify a pattern of ‘healthy ageing’ markers and then showing that people with Alzheimer’s deviate from this pattern.

“People shouldn’t take these findings to mean that most cases of Alzheimer’s are inherited as this is not true. The markers identified in this study are affected by the complex interaction between genetic and environmental factors and we’ll need further research to fully understand what they are telling us about the disease process.

“We do urgently need better ways to accurately diagnosis Alzheimer’s and other dementias and need to see more research like this to ultimately develop new tests that can be used in the clinic.”

Dr Tara Spires-Jones, Reader and Chancellor’s Fellow, Centre for Cognitive and Neural Systems, University of Edinburgh, said:

“This is a very interesting study that looked for a molecular signature of ageing in muscle from 15 young and 15 older people. The molecular signature that the authors found in these 30 people was then examined in brain and blood sample molecular data from hundreds of people published in several previous studies. Lower “scores” on this molecular signature of healthy ageing were found in patients with dementia compared to healthy controls. This is one of a number of recent studies aiming to develop a blood test capable of detecting the early stages of dementia. This is important because early detection will be critical to effective treatments for dementia.

“While this study looks promising, it is worth noting that it is not yet a fool proof blood test for dementia. While an improvement over many studies, it appears from the data that people with dementia would not always be different from controls on this test. There will also need to be further validation from independent groups.”

Dr Eric Karran, Director of Research, Alzheimer’s Research UK, said:

“Advances in genetic technologies over the past decades are now allowing scientists to profile the complexities of the human body in more detail than ever before. One of the biggest questions in human biology is how we age, and how this process impacts our wider health and risk for conditions like Alzheimer’s. 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. The ‘biological age’ measured by this test did not seem to be altered by important health parameters such as blood pressure, which we know can be risk factors for dementia. It will be important to determine how the ‘biological age’ score interacts with known population genetic risk factors for diseases like Alzheimer’s.  Much of the data in the study represents a snapshot in time, and it will be important to explore further how a person’s biological age score correlates with their health and survival in later life.

“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. Furthermore, tests that confirm actual pathological changes in the brain will continue to be used for confirming or ruling out clinical diagnoses. This study will need to be repeated and validated in a larger group of people to know whether it could be a useful clinical test for Alzheimer’s or how it could improve current research practices. With an increasingly ageing population in the UK and around the world, it’s important to invest in research in this area to help understand and improve health today and for future generations”

‘A novel multi-tissue RNA diagnostic of healthy ageing relates to cognitive health status’ by Sood et al. published in Genome Biology on Monday 7th September. 

Declared interests

Dr Doug Brown: Nothing to declare

Dr Tara Spires-Jones: I don’t have any conflicts.  

Dr Eric Karran: ARUK were listed funders on this study, but Eric doesn’t have any other conflicts that would be relevant.