Older Adults Often Underestimate How Long They'll Actually Live

Older people often have a good idea of how long they have left to live, and those who get it wrong tend to err on the pessimistic side, researchers say. A study using data from the long-running National Survey of the Japanese Elderly found that people who believed they'd live longer generally did, even after researchers adjusted for age, sex, income, education, and health, ScienceAlert reports. Out of around 2,400 people asked in 1996 what age they expected to live to, almost 400 said they didn't know. Over the next 28 years, almost 60% of those who gave an answer outlived their forecasts, researchers say.

Many appeared to latch onto 80 as a target age, a figure close to Japan's life expectancy at birth in 1996, though researchers say that's a poor guide for someone who has already made it to older age. The study, led by Shohei Okamoto of the University of Tsukuba, doesn't claim positive thinking adds years; it suggests people draw on subtle cues about their health, habits, and family history.

Women and better-educated participants were especially likely to underestimate their remaining years. Those in poorer health, however, were more likely to overestimate how many years they had left. That guesswork has real-world stakes, the authors note. "Underestimating life expectancy may lead to insufficient retirement funds, while overestimating it could result in unnecessary frugality or even poverty," they wrote.