Why do some people seem to age slower than others?

One way researchers approach this question is to look beyond a person’s age in years at their “biological age”, which reflects the health of cells and organs. But what’s the best way to measure biological age? Well, in a new study published in Science Advances, researchers from Japan report that blood markers of stress might be the answer.

The scientists studied more than 100 people, and they developed an AI model that estimates biological age by analyzing hormones involved in stress responses, metabolism, and immune function. The hormones themselves are nothing new, but they can vary significantly from one person to the next, making their effects on health and aging hard to interpret. However, the researchers’ AI engine took into account ratios and combinations of hormone levels, which allowed them to compare individuals and get a more personalized measure of biological age. One of their most striking findings involved cortisol, the body’s primary stress hormone, which played a big role in the AI model. In fact, they found that when cortisol levels doubled, biological age increased by about 50%! This finding lines up with lots of other evidence that chronic stress can accelerate aging, making stress management a critical factor in healthy aging.

Beyond stress, the researchers’ AI model also revealed that as people grow older, differences in biological age generally widen. This means that while some people age at a typical or “normal” rate, others may experience significantly accelerated aging due to factors like lifestyle, genetics, and environmental influences (and stress, of course). But there’s good news, too—because the opposite is also true. That is, at any given time, some people are aging slower than others, and for the same reasons (including stress!).

What does this mean for you?

Well, this new study is important because any improvements in our ability to measure biological age could lead to earlier disease detection, customized wellness plans, and even targeted interventions to slow aging. It also points to the idea that AI-driven health monitoring and personalized recommendations for reducing biological age could be on the horizon. But for now, this research primarily points to the idea that stress really plays an important role in shaping how quickly our bodies deteriorate over time. The good news is that we know at least some ways to deal with this. The National Council on Aging has some great tips on reducing stress here, and the National Institute on Aging has some additional, evidence-based suggestions here.