Scientists are finding that people who feel younger than their chronological age are typically healthier and more psychologically resilient than those who feel older. They perform better on memory tasks and are at lower risk of cognitive decline. In a study published in 2018, a team of South Korean researchers scanned the brains of 68 healthy older adults and found that those who felt younger than their age had thicker brain matter and had endured less age-related deterioration. By contrast, people who feel older than their chronological age are more at risk for hospitalisation, dementia and death. "We have found many, many predictive associations", says Yannick Stephan, an assistant professor of health and ageing psychology at the University of Montpellier in France who has been at the forefront of subjective age research. If you're over 40, chances are you feel younger than your driver's license suggests. Some 80 percent of people do, according to Dr. Stephan. A small fraction of people - fewer than 10 percent - feel older. The discrepancy between felt and actual age increases with the years, Dr. Terracciano said. At age 50, people may feel about five years, or 10 percent, younger, but by the time they're 70 they may feel 15 percent or even 20 percent younger. Most of the research on subjective age is based on associations between how old people feel and their health status, so it cannot establish cause and effect. It's not clear, for example, whether feeling younger actually makes people healthier, or whether people who are already healthy tend to feel younger. But by simply asking people how old they feel, Dr. Stephan says, doctors might be able to identify who is most at risk for health problems.