Tuesday, April 26, 2005

The Leg Bone is Connected to the Jaw Bone

Found via Psychiatry Source, here is an article that indicates a possible connection between the hormonal changes associated with depression, and loss of bone mineral density.  It was a small study, consisting of 19 humans, and it is not sufficiently detailed to allow clinically meaningful conclusions.  Thus, it is of interest more from a basic science perspective than a medical perspective:
The role of stress-induced cortisol in the relationship between depression and decreased bone mineral density
Biological Psychiatry, Volume 57, Issue 8, Pages 911-917 (15 April 2005)
Patricia M. Furlan, Tom Ten Have, Mark Cary, Babette Zemel, Felix Wehrli, Ira R. Katz, David R. Gettes, Dwight L. Evans

This study was designed to test the hypothesis that cortisol mediates the relationship between bone density and depression in postmenopausal women.

Nineteen women aged 52–79 who had been assessed for bone mineral density by dual-energy x-ray absorptiometer (DEXA) were evaluated for depression and anxiety. Diurnal and stress-induced measures of salivary cortisol were obtained during the following week and at a laboratory session involving a speech task.

Nine volunteers reported depression while 10 were never depressed. Ever depressed women had significantly lower total lumbar and right femur DEXA Z scores than never depressed (t(17) = 2.5, p = .019 and t(17) = 2.06, p = .05, respectively). Ever depressed women demonstrated a significant increase in salivary cortisol (area under the curve (AUC) = 27.83, SD = 37.64) compared to never depressed women (AUC = -13.34, SD = 19.55) (t(17) = -3.041, p = .007) during a psychological challenge. There were significant inverse relationships between salivary cortisol AUC values and bone density Z scores at every measured bone site. Mediation analyses suggest that 51 – 67% of the association between depression and bone density could be attributed to stress-induced changes in cortisol.

Cortisol hypersecretion in response to stress may, in part, explain the impact of depression on bone density in post-menopausal women.

Although there are numerous potentially-confounding variables, this study shows that depression is a complex phenomenon.  For those who may be tempted to think it is "all in the head," please realize that this is not the case.  We can't be sure that it is the changes in cortisol regulation that result in changes in bone mineral density, but we can be sure that depression is associated with changes in the endocrine and skeletal systems.