Older women who suffer from major depression are at greater risk of developing urinary incontinence than women of the same age who are not depressed, new research shows.

Since urinary incontinence and depression often occur together in women, Dr. Jennifer Melville from the University of Washington in Seattle and colleagues set out to determine if a causal relationship exists between the two conditions.

Previous studies demonstrated a high rate of depression among women being treated for urinary incontinence but none had examined whether one condition led to the other.

Melville’s team hypothesized that because the brain chemical serotonin plays a role in both depression and bladder function, the physiological changes brought on by one illness may set the stage for the other.

“We thought maybe we’d see it both ways. In some people because of chemical changes in the body, depression could lead to incontinence but in others, the cause would run the other way because of the psychologic reaction to incontinence,” Melville told Reuters Health in a telephone interview.

They scoured data gathered over six years in the ongoing Health and Retirement Study of the financial and physical health of recent retirees in 70,000 households.

The investigators conducted two analyses. In the first, women who entered study with depression were examined to see if urinary incontinence developed. The second analysis looked at women who entered the study with urinary incontinence to see if depression was reported at follow-up.

In this sample of nearly 6,000 women with an average age of 59 years, “we just saw the one pathway, very strong, leading from depression to incontinence and in fact incontinence not leading to depression,” Melville said.

The unambiguous results of the study were not expected, she admitted. “We were surprised at was how one-sided the effect looked.”

Doctors can use the findings in the current study “to counsel women with depression about a potentially increased risk for development of urinary incontinence or what to do if incontinence symptoms begin to emerge,” Melville and her colleagues write in the American Journal of Obstetrics and Gynecology.

The loss of bladder control may take a large toll emotionally because of the impact it can have on daily life, they note in their report. Many people feel humiliated and helpless about their condition and restrict social and work activities as a result.

The findings, Melville and colleagues add, also highlight “the importance of addressing depression urgently as a public health priority,” because of the effect it may have on other biological functions.

SOURCE: American Journal of Obstetrics and Gynecology, November 2009.