DALLAS, July 3 -- High blood pressure, prior stroke and having an irregular heartbeat are all risk factors for stroke. An Australian study examining stroke risk, however, suggests that impaired breathing may increase stroke risk, while being married may lower it.
In this month's Stroke: Journal of the American Heart Association, Australian researchers examined hospital and death records of 2,805 men and women over the age of 60 during an eight-year period.
While the scientists substantiated many previously-held beliefs about stroke risk, they also discovered that people who were married had a 30 percent lower risk of stroke. Married women, in particular, had a 46 percent lower risk of stroke. It may not be time to run out and buy the engagement ring, however, since the scientists say more research will be needed to explain the findings about marriage.
"The reasons for this are unclear," says the study's lead author Leon A. Simons, M.D., of St. Vincent's Hospital, Darlinghurst, New South Wales, Australia. "It may relate to differential benefits from social support in marriage."
The scientists also found that those whose breathing -- peak expiratory flow -- was most impaired by chronic bronchitis had a 77 percent higher risk for having a stroke when compared to those whose breathing was the least impaired.
"The relationship between impaired peak expiratory flow and ischemic stroke has not, to our knowledge, been previously reported," says Simons. "A suggested link between inflammation and atherosclerosis is very topical, especially with recent research on the link between respiratory infection and heart disease. Our data allows the possibility of speculation and extrapolation, but more specific research needs to be done on this link."
The scientists were looking for reasons why some people were more susceptible than others of having an ischemic stroke, which occurs when the blood supply to the brain is cut off. Nearly 80 percent of strokes are ischemic.
People in the study who had a prior stroke had a 227 percent higher risk of having another stroke. In addition, those who had the highest blood pressure readings had a 67 percent higher risk of a stroke, and people who had an irregular heartbeat -- a condition known as atrial fibrillation -- had a 58 percent higher risk of a stroke.
While the researchers did not make a direct link between depression and stroke risk, they say their study has raised the possibility that clinical depression and stroke may share a common development.
"There is evidence from studies that changes in the brain are associated with onset of depression in late life," says Simons. "These changes appear to be associated with vascular risk factors such as hypertension or diabetes, but this will require confirmation in future studies."
The study found that women had a 48 percent lower risk of having a stroke and those who had high blood levels of good, high-density lipoprotein (HDL) cholesterol also had a reduced risk. People who were physically disabled had a 59 percent higher risk of stroke.
"These findings suggest that death and illness associated with ischemic stroke can be predicted by various clinical indicators, some of which may be amenable to intervention," says Simons.
Co-authors include John McCallum, D.Phil.; Yechiel Friedlander, Ph.D.; and Judith Simons, M.A.C.S.
For copies of the study, please telephone: 214-706-1173
NR 98-4918 (Stroke/Simons)
Media advisory: Dr. Simons can be reached by phone 61 2 9361 2301 at fax
at 61 2 9361 2234 or by or by e-mail at exb0072@vmsuser.acsu.unsw.edu.au.
(Please do not publish numbers.)