A good mood, gratitude and even pessimism about the future are all credited with making aging more tolerable and lifespans longer.

A spate of research has surfaced recently analyzing the relative health effects of having a good mood as an older adult, with conflicting studies suggesting either a longer lifespan or increased risk of disabilities. So, what gives?

The first study, conducted by Ohio State University in conjunction with researchers from the University of Michigan, Linköping University in Sweden and Cornell University, showcased the power of positive moods in helping older people with brain tasks. In a study of 46 people aged 63 to 85, half were put into a good mood by receiving a thank-you card and two small bags of candy when they arrived at the lab for the experiment. The “neutral mood” participants did not receive any tokens of thanks. The participants in this study then completed games on a computer, which tested decision-making and working memory, and in both, the optimistic group scored better than the neutral group (mood had no effect on some measures, such as speed of processing or vocabulary).

Also on the “pro good-mood” side, a recent University College London study revealed that elderly people who were happy with their lives lived up to 20-35 percent longer than unhappy contemporaries. Cardiologist Dr. Cynthia Thaik penned a Huffington Post column explaining this was significant because gratitude “reminds you of what truly matters in life…[and] makes your problems seem less daunting and more manageable.” In fact, she notes, according to the Centers for Disease control and Prevention, up to 90 percent of all illness and disease may be stress-related.

But another study, published by the American Psychological Association and conducted by researchers from the University of Erlangen-Nuremberg in Germany, claims that the key to a longer life is actually managing expectations. “Our findings revealed that being overly optimistic in predicting a better future was associated with a greater risk of disability and death within the following decade,” said lead author Frieder R. Lang, Ph.D. In fact, Lang added, “Pessimism about the future may encourage people to live more carefully, taking health and safety precautions.”

In the study, the researchers measured volunteers’ current and future life satisfaction on a scale of 0 to 10 and measured the difference between their anticipated life satisfaction reported in 1993 and actual life satisfaction reported in 1998. They analyzed the data to determine age differences in estimated life satisfaction and rates of disability and death reported between 1999 and 2010. But, Lang said, the findings do not contradict theories that unrealistic optimism about the future can sometimes help people feel better when they are facing inevitable negative outcomes, such as terminal disease. “These findings shed new light on how our perspectives can either help or hinder us in taking actions that can help improve our chances of a long, healthy life.”

What do you think about the abundance of stories that measure good mood, gratitude and pessimism as contributing factors to living better and longer? Would research on pessimism and longevity make you dial back your optimism, or will all the research in the world leave you determined to keep your same outlook?

For more information about personality and longevity, we invite you to visit our Be Well for Life page and watch a series of short videos.