Having an optimistic spouse predicted better mobility and fewer chronic illnesses over time, even above and beyond a person's own level of optimism, according to a new University of Michigan study.

The findings appear in the current issue of Journal of Psychosomatic Research.

Researchers used data from the Health and Retirement Study, a national study of American adults over the age of 50. The study's 3,940 heterosexual adults (1,970 couples) were tracked for four years and reported on their physical functioning (mobility, motor skills), health, and number of chronic illnesses.

Past research found that social support may partly explain the link between optimism and enhanced health because optimists are more likely to seek social support when facing difficult situations, have a larger network of friends who provide social support, are more well liked by friends, and those friends also provide more support. In addition, optimists engage in healthier lifestyles that simultaneously minimize health risk factors for illness, said Eric Kim, a doctoral student in the U-M Department of Psychology and the study's lead author.

"A growing body of research shows that the people in our social networks can have a profound influence on our health and well-being. This is the first study to show that someone's else optimism could be impacting your own health," he said.

In close relationships, optimism predicts enhanced relationship satisfaction and better cooperative problem solving.

"So practically speaking, I can imagine a optimistic spouse encouraging his or her partner to go to the gym, or eat a healthier meal because the spouse genuinely believes the behavior will make a difference in health," he said. "Identifying factors that protect against declining health is important for the increasing number of older adults who face the dual threat of declining health and rising health care costs."

The study's other authors included William Chopik, a psychology graduate student, and Jacqui Smith, a professor in the Department of Psychology and Institute for Social Research.