According to researchers, knee OA affects some 55 percent of people over age 40 in Japan. A research team from the country recently published a study in the Journal of the American Geriatrics Society examining the effects of knee pain on depression since, until now, few studies have focused on how knee pain and impaired knee function relate to depression.

To learn more, the researchers examined information from 573 people aged 65 or older who participated in the Kurabuchi Study, an ongoing look at the health of older adults living in central Japan.

When the study began (between 2005 and 2006) none of the participants had symptoms of depression. Two years later, nearly all of them completed follow-up interviews. The participants answered questions about their knee pain and were evaluated for symptoms of depression.

Nearly 12 percent of the participants had developed symptoms of depression. People who experienced knee pain at night while in bed, while putting on socks, or while getting in or out of a car were more likely to report having symptoms of depression, noted the researchers.

The researchers concluded that asking older adults with knee pain whether they have pain at night in bed, when putting on socks, or while getting in or out of a car could be useful for helping to screen people at risk for developing depression.