Researchers Explore Link Between Low Bone Mineral Density and Stroke Risk in Women

Several risk factors for stroke have been clearly identified, including age, family history of stroke, smoking, lack of physical activity, and high blood pressure. Now, a new study published in the medical journal, Stroke, finds that women who have strokes tend to have lower bone mineral density (BMD) measurements than women who do not suffer strokes, suggesting that low BMD may predict stroke risk in women. However, the study did not find a relationship between low BMD and stroke in men.

Bone mineral density (BMD) measures the amount of calcium in the bones. A patient’s BMD can be measured by taking dual energy x-rays (DEXA) or CT scans (Osteo CT or QCT) of bones at several sites of the body, such as the spinal column, wrist, arm or leg. Low BMD is a sign of osteoporosis, a degenerative bone disease, and can increase the risk of bone fractures.

In the study, Dr. Torgeir Engstad and his colleagues from Norway took BMD measurements from the femoral necks of 63 stroke patients (33 women and 30 men) and 188 patients who do not have strokes. All of the patients were at least 60 years of age. BMD measurements were taken on the stroke patients six days after the onset of stroke. After analyzing the results, the researchers found that the BMD measurements for female stroke patients were 8% lower than the BMD measurements of patients who did not suffer strokes. However, Dr. Engstad and his colleagues did not find any differences in BMD measurements between male stroke patients and men who did not suffer strokes, suggesting that BMD may not play a key role in stroke risk for men.

The researchers also found that women who had the lowest BMD measurements (indicating the most bone loss) had a higher risk of stroke than women who had the highest BMD measurements. According to Dr. Engstad, it is unclear whether having low bone mineral density increases the risk of stroke or whether it indicates overall poor health, which can put patients at risk for stroke and other problems. While further studies are needed to help clarify the relationship between low BMD and stroke risk in women, Dr. Engstad believes that because female stroke patients have lower BMD, they should receive aggressive treatment after the stroke to prevent further complications.

Previous research has shown that stroke patients are at a higher risk of hip fractures. Another study conducted by Norwegian researchers and published in the journal, Osteoporosis International, found that a lack of mobility and weight-bearing activities can lead to significant bone loss in patients who have suffered strokes. The study also found that among the patients who were initially wheelchair bound after their strokes, learning to walk again within the first two months of the stroke, even if that meant depending on others for physical support, reduced bone loss after immobilization.

Low bone mineral density (BMD) can lead to symptoms of osteoporosis, including back pain, height loss due to a curved spine, broken bones, tooth loss, etc. It is estimated that osteoporosis accounts for more than 1.5 million bone fractures each year. Before a woman reaches her mid-30s, her body gains more bone than it loses. Around age 35, this process balances out. However, the onset of menopause (and a decrease in the female hormone, estrogen) around 50 years of age may speed up the rate of bone loss. If bone loss becomes severe, a woman may develop osteoporosis.

There are several ways women can increase their bone mineral density:

Maintain a diet rich in calcium and vitamin D
Engage in weight-bearing exercises
Do not smoke and limit alcohol intake
Consider taking hormone replacement therapy (HRT) or other drug therapies, such as raloxifene (brand name, Evista), alendronate (brand name, Fosamax), calcitonin (brand name, Miacalcin), risedronate sodium (brand name, Actonel)
Click here to learn more about increasing bone mineral density.

Additional Resources and References

The study, "Bone Mineral Density in Acute Stroke Patients: Low Bone Mineral Density May Predict First Stroke in Women," is published in the January 2001 issue of Stroke. An abstract of the study is available at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd
=Retrieve&db=PubMed&list_uids=11136913&dopt=Abstract
The study, "Walking after Stroke: Does it Matter? Changes in Bone Mineral Density within the First 12 Months after Stroke. A Longitudinal Study," is published Volume 11, Issue 5 of Osteoporosis International. An abstract of the study is available at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd
=Retrieve&db=PubMed&list_uids=10912838&dopt=Abstract
To learn more about stroke, please visit http://www.imaginis.com/stroke/
To learn more about osteoporosis, please visit http://www.imaginis.com/osteoporosis/osteo_whatis.asp

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