Depression Linked with Low Bone Density
Premenopausal women struggling with depression have lower bone mass than do non-depressed women in the same age range, according to a report in the Archives of Internal Medicine.
The bone loss was most pronounced in certain regions of the hip, which is troubling given that hip fractures are one of the most serious - and potentially fatal - consequences of osteoporosis.
The level of bone loss seen in the depressed women was the same or higher than that associated with other, established risk factors for osteoporosis, including smoking, low calcium intake, and lack of physical exercise, the researchers say.
The findings could have implications for the prevention of osteoporosis.
Osteoporosis, or porous bone, is a disease in which there is a loss of bone mass and destruction of bone tissue. This process causes weakening of the bones and makes them more likely to break. The bones most often affected are the hips, spine, and wrists.
Osteoporosis affects over 10 million Americans, with women four times more likely to develop osteoporosis than men.
Another 34 million people have low bone mass and therefore have an increased risk for osteoporosis. Estrogen deficiency is one of the main causes of bone loss in women during and after menopause. Women may lose up to 20 percent of their bone mass in the five to seven years following menopause.
"Premenopausal women with depression should be screened for low bone mass," says Dr. Giovanni Cizza, senior author of the study who conducted the research while at the National Institute of Mental Health (NIMH).
"They should do a bone mineral density measurement, because osteoporosis is a silent condition,” he says. “Until someone fractures, you don't know you have osteoporosis."
Dr. Cizza is now at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
A woman's bone mass peaks during youth and then thins after menopause. Previous preliminary studies had suggested that depression might be a risk factor for low bone mass in older women.
For this study, Dr. Cizza and his colleagues looked at 89 women with depression and 44 women without depression. The women ranged in age from 21 to 45. The depressed women were taking antidepressant medications.
Seventeen percent of the depressed women had thinner bone density in the femoral neck, a vulnerable part of the hip. Only 2 percent of non-depressed women, by contrast, had thinner bone in this area.
Twenty percent of depressed women also had low bone density in the lumbar spine, compared with 9 percent of the non-depressed women.
Blood and urine samples also revealed that the depressed women had lower levels of "good" proteins called cytokines. "The bad cytokines that may cause bone loss are higher," says Dr. Cizza.
It is not clear what role antidepressants might play, but by relieving the depression, the medications may also help bone mineral density, the researchers say.
Always consult your physician for more information. |
Bone densitometry (or bone density) testing is primarily performed to identify persons with osteoporosis and osteopenia (decreased bone mass) so that the appropriate medical therapy and treatment can be implemented.
Early treatment helps to prevent future bone fractures. It may also be recommended for persons who have already fractured and are considered at risk for osteoporosis.
The bone densitometry test determines the bone mineral density (BMD). Your BMD is compared to two norms - healthy young adults (your T-score) and age-matched (your Z-score).
First, your BMD result is compared with the BMD results from healthy 25- to 35-year-old adults of your same sex and ethnicity. The standard deviation (SD) is the difference between your BMD and that of the healthy young adults. This result is your T-score. Positive T-scores indicate the bone is stronger than normal; negative T-scores indicate the bone is weaker than normal.
According to the World Health Organization, osteoporosis is defined based on the following bone density levels:
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A T-score within 1 SD (+1 or -1) of the young adult mean indicates normal bone density.
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A T-score of 1 to 2.5 SD below the young adult mean (-1 to - 2.5 SD) indicates low bone mass.
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A T-score of 2.5 SD or more below the young adult mean (> - 2.5 SD) indicates the presence of osteoporosis.
In general, the risk for bone fracture doubles with every SD below normal. Thus, a person with a BMD of 1 SD below normal (T-score of -1) has twice the risk for bone fracture as a person with a normal BMD. A person with a T-score of -2 has four times the risk for bone fracture as a person with a normal BMD.
When this information is known, people with a high risk for bone fracture can be treated with the goal of preventing future fractures.
Secondly, your BMD is compared to an age-matched norm. This is called your Z-score. Z-scores are calculated in the same way, but the comparisons are made to someone of your age, sex, race, height, and weight.
Always consult your physician for more information.
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