The secrets to happiness and depression for the oldest among us has been uncovered by Iowa State researchers.
In a study of 158 Georgia centenarians, the researchers found that past satisfaction with life-even if it's simply recalling isolated career accomplishments-is the key to happiness in our oldest years.
"The past is the best predictor of the future, so you're not going to turn your life around at 85 or 90," said Peter Martin, director of Iowa State's gerontology program and a professor of human development and family studies (HDFS), who collaborated on both studies. "But it's also good to know that past accomplishments and the happiness that you had-looking back at your past-carries you through these very last years."
For the depression study, researchers added 78 octogenarians (people 80 or older) to the happiness centenarian sample. They found that diminished cognitive problem-solving ability was a significant predictor of depressive symptoms in octogenarians, while living in a nursing home and greater neurotic tendencies increased depression among centenarians.
Both studies were published online in the Jan. 26 issue of the journal Gerontology. Jennifer Margrett, an assistant professor of HDFS, was the lead author on the depression study. Alex Bishop, an assistant professor of human development and family studies at Oklahoma State University (who was a doctoral student at Iowa State), was lead author of the happiness study.
In one study, researchers analyzed the subjects' responses to a series of questions that assessed their happiness, perceived health, social provisions, economic security and life satisfaction. While there was no indication that resources affect happiness, past life satisfaction-even individual achievements-was found to have a direct association.
"You can be not overly satisfied with your overall current capacity and physical well-being, but you can still be a very happy person because there's a lot you can contribute just by sharing some of the things that nobody knew because it was 80 or 90 years ago," said Martin, who is also in the second year of a three-year study of Iowa centenarians.
In the second other study, researchers measured depressive symptoms, demographics and functional indicators, cognition and personality in the subjects. They then compared the ability of cognition, personality, and demographic and functional indicators in explaining depressive symptoms in the octogenarians and centenarians respectively.
They were surprised to learn that overall cognition was not a stronger predictor of depressive symptoms at either age. Rather, it was the loss of the subject's control-problem-solving in the octogenarians, and choosing where they lived in the centenarians-that tended to depress them.
"In the case of the octogenarians, it's not so much your intellectual ability as it is the ability to come up with a solution to a particular task that you used to be able to solve in your 60s and 70s," Martin said. "And so for the first time, you realize that there may be decline in being able to manage tasks.
"And at 100, it's not so much the surrounding of the nursing home that gets you depressed," he added. "But in a nursing home, two things have changed. First, there's a sign that you cannot take care of yourself anymore. And then there's the sign that you know you only have limited time to live, which is different for an 80-year-old."
The research also confirmed that worry and anxiety contribute to depression in centenarians.