According to the researchers, this new knowledge further emphasizes the importance of health professionals paying attention to their patients family history to prevent stroke.
“Patients in the risk zone of getting a heart attack or a stroke should be made aware that a genetic predisposition exists”, says Erik Ingelsson, Professor of Cardiovascular Epidemiology at Karolinska Institutet. “However, the increased familial risk may not solely be due to genetics. Similar lifestyle within families could also be involved, and lifestyle can of course be modified.”
Ischemic strokes are caused by blood vessel occlusion that cuts off blood flow to parts of the brain, causing reduced supply of oxygen. The current findings, which are published in the scientific journal Circulation: Cardiovascular Genetics, come from the first large study to examine the combined influence of age, gender and sibling history on stroke risk. The analysis included hospital discharge and cause of death records in 30,735 people who had a sibling with a stroke, and 152,391 adults of a similar age with no history of a sibling having a stroke. For each stroke diagnosed, researchers tracked whether a sibling had a stroke during the remainder of the study period.
The results of the study show that if your brother or sister had had a stroke, you may be at least 60 percent more likely to have one too. Half-siblings of stroke patients were 41 percent more likely to get a stroke themselves. If the sibling was 55 or younger at the time of the stroke, the risk almost doubled for having one yourself at 55 or younger. However, the gender of either sibling did not influence the inherited stroke risk.
Because there was no information on other medical risk factors for ischemic stroke, such as high blood pressure and abnormal lipid levels, the researchers could not determine whether the familial influence increased stroke risk directly or through intermediate factors.
“But either way, if your sibling has had a stroke, it may be a good idea to pay more attention to lifestyle habits such as diet and exercise, and to have your blood pressure checked at regular intervals”, says Professor Ingelsson.
The study was supported by a grant from the Swedish Research Council within the Swedish Initiative for research on Microdata in the Social and Medical Sciences (SIMSAM).
Familial Effects on Ischemic Stroke The Role of Sibling Kinship, Sex, and Age of Onset
Circulation: Cardiovascular Genetics, an American Heart Association journal, online 10 April 2012, DOI: 10.1161/CIRCGENETICS.111.96224