The study is based on mice, not people, but it indicates a mind-bone link, the researchers note.
The findings "point for the first time to depression as an important element in causing bone mass loss and osteoporosis," says Raz Yirmiya, PhD, MSc, of The Hebrew University of Jerusalem, in a university news release.
"The connection between the brain and the skeleton in general, and the influence of depression on bone mass in particular, is a new area of research about which we still know very little," says Yirmiya, a psychology professor and one of the researchers on the study.
Their findings appear in Proceedings of the National Academy of Sciences.
Depression & Bones
But, they say, until now it hasn't been clear which comes first -- depression or osteoporosis.
Yirmiya's team studied the link in male mice. Some of the mice lived in stressful conditions, with dirty cages, bright lights, or loud noises. The other mice lived in clean cages without those stresses.
The stressed-out mice acted depressed. Compared with the nondepressed mice, they drank less of the sugary water in their cages and didn't respond as much when the scientists put a young mouse in their cage.
After four weeks, the depressed mice had lost bone density, the study shows. The problem: They had a drop in bone-building cells called osteoblasts.
The nondepressed mice had no such bone problems.
Bones are always remodeling themselves. They build themselves up and break themselves down over and over again.
If that process goes awry, and the breakdown outpaces the buildup, bones become less dense.
Such porous bones are less supportive than denser bones. Osteoporosis and serious breaks can be the result.
When the depressed mice drank water laced with imipramine, their depressioneased and their bone loss stopped.
The researchers found that the depressed mice that hadn't gotten imipramine had high bone levels of the stress hormone norepinephrine.
When the scientists blocked norepinephrine in those mice, their bone loss also stopped.
The findings suggest a link between the bones and the brain, Yirmiya's team concludes – albeit one not studied in people yet.
The researchers aren't suggesting any particular treatment for depression or osteoporosis. Your doctor can provide information on treatments if needed.