Dr. Andrew Steptoe of University College London assessed the enjoyment of life of 3,199 men and women age 60 and older in Britain over eight years.
The study participants were divided into three age categories -- 60 to 69, 70 to 79 and 80 and older -- and asked the following four questions to assess their enjoyment of life on a four-point scale: "I enjoy the things that I do," "I enjoy being in the company of others," "On balance, I look back on my life with a sense of happiness" and "I feel full of energy these days."
Researchers used personal interviews to determine whether participants had impairments in daily activities such as getting out of bed, getting dressed, bathing or showering. They gauged walking speed with a gait test.
"The study shows that older people who are happier and enjoy life more show slower declines in physical function as they age," Steptoe said in a statement. "They are less likely to develop impairments in activities of daily living such as dressing or getting in or out of bed, and their walking speed declines at a slower rate than those who enjoy life less."
Participants in the 60- to 69-year bracket had higher levels of well-being as did those with higher socioeconomic status and education and those who were married and working. Not surprisingly, people with chronic illnesses such as heart disease, diabetes, arthritis, stroke and depression had lower levels of enjoyment of life, Steptoe said.
The study, published in the Canadian Medical Association Journal, found people with low well-being were more than three times as likely as their positive counterparts to develop problems in their daily physical activities.
"This is not because the happier people are in better health, or younger, or richer, or have more healthy lifestyles at the outset, since even when we take these factors into account, the relationship persists," Steptoe explained. "Our previous work has shown that older people with greater enjoyment of life are more likely to survive over the next eight years; what this study shows is that they also keep up better physical function."