Use of Bone Biopsy to Better Understand the Causes of Decreased Bone Mineral Density in Depression

Overview

In this study researchers would like to learn more about the low levels of bone mineral density seen in approximately half of women in their forties diagnosed as currently having or previously had depression. Bones are always undergoing a process of building (formation) and breakdown (resorption). This process is referred to as bone remodeling. When more bone is formed than resorbed, the density (level of calcium) in bone increases and the bones become stronger. However, if more bone is resorbed than formed the density of bone decreases and the bones become weak. This condition is called osteoporosis. It is unknown if women with depression have decreased bone mineral density as a result of too much breakdown of bone or not enough building. It is important to know the cause of low bone mineral density because it will influence the way a patient is treated. Medications like bisphosphonates are used when there is too much bone breakdown. Growth hormone replacement can be given in cases where there is not enough bone production. Presently, bone biopsy and a procedure known as histomorphometry can determine what processes are going on in bones. Researchers have decided to use a sample of bone (biopsy) from part of the hip bone (iliac crest). In addition, researchers will collect a sample of bone marrow (the soft tissue found in the center of bones) to tell them more about the biochemical, cellular, and molecular processes that may be contributing to the problem of decreased bone density in depressed premenopausal women.

We have recently found that premenopausal women with past or current depression show clinically significant decrements in bone mineral density in the hip and spine, rendering more than 40% at present risk for osteoporotic fracture. Recent pharmacologic advances provide the opportunity to ameliorate or reverse this clinically significant loss of bone mineral density. Available agents such as bisphosphonates or growth hormone are each preferentially effective in the contexts of increased and decreased bone turnover, respectively. It is currently not known whether the decrease in bone mineral density in depression is associated with increased or decreased bone turnover because the many endocrine changes associated with depression of possible relevance to decreased bone mineral density have disparate effects on bone turnover dynamics. At present, the only definitive way to determine the status of bone turnover in humans is via bone biopsy and histomorphometric evaluation. In addition, bone marrow routinely obtained during standard bone biopsy would provide the opportunity to culture osteoblast and osteoclast progenitor cells to determine possible abnormalities in differentiation and function as a means of exploring the cellular and molecular mechanisms of decreased bone mineral density in depression. In light of the high incidence of depression in women, decreased bone mineral density in patients with past or current depression has considerable public health implications.