Everyone dies, but a new study says feeling sprightly might suggest a person has more time left than people who feel their age or older.
Older people in the UK who felt at least three years younger than their chronological age were less likely to die over the next eight years than those who felt equal to or older than their actual age, researchers found.
"This relationship has been shown before, but not in such a large scale study in which we were able to look at such a range of possible explanations," said co-author Andrew Steptoe of the epidemiology and public health department at University College London. "We still don't understand what the explanation really is."
Using data from a previous study on ageing, Steptoe and his co-author Isla Rippon analysed more than 6 000 adults who were at least 52 years old.
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In 2004 or 2005, researchers asked the participants how old they felt.
More than two-thirds felt at least three years younger than their real age, while a quarter felt their real age, and less than five percent felt more than a year older, according to the research letter in JAMA Internal Medicine.
Following the group through March 2013, the authors found that about 14 percent of those who felt younger had died, compared to about 19 percent of those who felt their age and about a quarter of those who felt older.
"The first thing we thought of is that people who feel older than their chronological age are sicker, and that is why they are at greater risk of dying," Steptoe told Reuters Health by email.
To account for that, the authors measured pre-existing health conditions including cancer, heart disease, diabetes, stroke, arthritis and other illnesses, which explained some of the link.
"But when we had taken these illnesses into account in our statistical models, the relationship with perceived age remained quite strong," Steptoe said. "We also measured mobility problems, lifestyle factors such as smoking, depression, and cognitive function. But none of these explained the relationship we saw."
Self-perceived age was associated with death from heart disease, but not from cancer, the authors found.
Great deal of variation in feelings
In the second half of life, most people feel younger than they are, averaging about nine years younger, Steptoe said.
"But there is a great deal of variation in these feelings," he said.
"The study is important because it provides further evidence that perceptions of ageing can have real consequences for the health of older individuals," said Becca R. Levy, associate professor of epidemiology and psychology at the Yale School of Public Health in New Haven, Connecticut.
"The findings show the need for society, which often influences these perceptions, to concentrate its efforts on enabling older individuals to view the process of growing old in a more positive light," Levy, who was not part of the new study, told Reuters Health by email.
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People who feel older are less likely to go out and about, are lonelier, less mobile and less physically active, Steptoe noted.
People shouldn't worry about how old they feel, he said.
"But it's certainly something that we as medical researchers should try and understand," Steptoe said. "Perhaps the beliefs and feelings that people have tell us something that our other measures of health and well-being do not capture."