Cortisol may mediate effect of depression on osteoporosis.

BALTIMORE -- Women with a history of depression appear to have increased cortisol levels in response to stress, a finding that may help explain the link between depression and osteoporosis, according to data presented at the annual meeting of the American Association for Geriatric Psychiatry.

Women with a history of depression had higher salivary cortisol levels in response to a stress-inducing situation than women without a history of depression, Patricia M, Furlan, Ph.D., of the University of Pennsylvania, Philadelphia, said in a poster presentation. The researchers also found that ever-depressed women also had lower bone mineral density (BMD) than never-depressed women.

The study involved 19 postmenopausal women (over age 50 years) recruited from a prior radiology study and who had been assessed for BMD in the past year. At the first visit, the women were assessed for a history of depression using several standardized tools. Ten of the women had no history of depression and nine did.

At the second visit, the women were asked to deliver a speech on the topic of their greatest success or failure. They were given a short period of time alone to prepare their speech and then were instructed to deliver the speech in front of a two-way mirror, knowing that they were being observed. Four saliva samples were collected before the speech task and six samples were collected after the speech at 10-minute intervals.

Women with a history of depression had significantly greater salivary cortisol levels in response to anticipatory anxiety than women who had no history of depression, measured as the area under the curve. Ever-depressed women had a mean area under the curve of 27.83, compared with -12.09 for never-depressed women. There were no differences in diurnal salivary cortisol levels between the groups.

Ever-depressed women had significantly lower lumbar and right and left femur BMD Z-scores than never-depressed women as well. More importantly, higher stress-induced cortisol levels were associated with lower BMD Z-scores. Although formal tests of mediation of cortisol on the depression effect on BMD were not statistically significant, the effect size range--37%-79%--suggests that cortisol has at least a partial mediating effect on the relationship between depression and osteoporosis, Dr. Furlan said.

Given that episodes of depression in the past appear to be associated with decreased BMD, it may be that the cumulative effects of the accompanying hormonal and nutritional abnormalities associated with depression may lead to lasting changes in peripheral tissues, such as bone.

BY KERRI WACHTER

Senior Writer