Longevity Briefs: How Can We Measure Biological Age?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: If we want to measure whether an anti-ageing treatment has worked, we need to be able to measure biological age. Biological age is a measure of a person’s health relative to the population average – if you have a biological age of 30, your body functions about as well as that of the average 30 year-old. In theory, any factor that reflects the biological processes of ageing (known as biomarkers of ageing) can be used to estimate biological age, from grip strength to epigenetic alterations. The problem with these methods is that ageing is driven by many processes, and no single method measures all of them at once. What’s more, ageing doesn’t occur at the same rate in all cells, tissues and organs – you could have the skin of a 40 year-old but the brain of a 50 year-old. This means that even the most widely respected methods of measuring biological age, such as methylation clocks, cannot be entirely trusted when it comes to studying rejuvenation treatments.

What did the researchers do: In this article, researchers review the most promising biological age measurement techniques that could soon be used in routine clinical practice. They discuss what makes a given technique promising, what needs to be improved for them to reach widespread clinical use, and how they have been used during the COVID-19 pandemic.

Key takeaway(s) from this research: Methylation clocks are currently the most widely accepted method of measuring biological age. In this technique, a person’s biological age is estimated based on the pattern of DNA methylation, a chemical modification to DNA that affects the regulation of gene expression. Studies have shown that methylation age can be used to predict disease severity and mortality in COVID-19 patients. This demonstrates the clinical potential of knowing someone’s biological age, as most diseases are more severe in older people. Other notable markers include blood biochemistry, microbiome composition and even behavioural markers, though these are currently understudied.

Many biomarkers of ageing work in large study populations because, on average, they correlate with biological age over thousands of participants. However, to be effective in a clinical setting, we need much more precise measurements. What’s more, a single biomarker of ageing doesn’t work well in people who already have a condition affecting that biomarker. For example, levels of inflammatory molecules won’t accurately reflect biological age in a person with a chronic inflammatory condition. This means that a good measurement of biological age needs to take multiple biomarkers into account. Artificial intelligence is proving valuable in developing calculators that amalgamate many different measurements, but these are still in development and are much more expensive.