(RxWiki News) Having a brother or sister who has suffered from a stroke can exponentially increase your risk of having a stroke -- especially if the sibling suffered a stroke when they were younger than 55.
Individuals whose sibling previously suffered an ischemic stroke, the most common type which occurs when blood flow to the brain is blocked, are at a 60 percent increased risk over average of suffering a stroke themselves.
"Talk to a cardiologist about risk if a sibling suffered a stroke."
Dr. Erik Ingelsson, senior author of the study and professor of cardiovascular epidemiology at the Karolinska Institutet in Sweden, urged healthcare clinicians to give as much attention to a family history of stroke in siblings as they do to parents, and to ensure patients are aware of the genetic predisposition.
During the study investigators reviewed national hospital discharge and death records from 1987 to 2007. For each of 152,391 ischemic stroke patients, researchers traced a sibling who had suffered a stroke during the remainder of the 20-year study period.
At the time of the brother or sister's stroke, patients were an average age of 64. Researchers also examined the records of 30,735 stroke patients who did not have a sibling who suffered a stroke.
They found that if a sibling had a stroke under the age of 55, it nearly doubled the stroke risk. In addition, if a brother or sister had a stroke before 55, the risk of a stroke prior to age 55 was increased by 94 percent.
The risk also was increased for half-siblings that shared only one parent. The full siblings of a stroke patient were 64 percent more likely to suffer a stroke in comparison to a 41 percent increased risk for half-siblings. Sibling gender did not influence the risk.
Dr. Ingelsson said the added risk may not be due to genetics alone. He said similar lifestyle habits, such as diet, exercise or blood pressure control, also could play a role.
However, no information was available about other possible medical risk factors for ischemic stroke, such as elevated cholesterol or blood pressure. This means that researchers were unable to determine whether the increased risk was associated with genetic or environmental factors.
In addition, stroke subtype information was not available, which may have limited the study since certain stroke types carry higher inherited risks.
The study, funded by a grant from the Swedish Research Council, was recently published in American Heart Association journal Circulation: Cardiovascular Genetics.