Being overweight or obese is associated with a number of known risk factors for stroke. However, new research shows that excess weight has varied effects on different types of stroke.
When blood flow to the brain is cut off, it is referred to as a strokeand is a medical emergency.
Without blood and the oxygen it carries, parts of the brain begin to die.
The long-term effects of a stroke depend on which parts of the brain are damaged and how large the area of damage is.
Stroke is a leading cause of death in the United States, killing almost130,000 Americans each year; that equates to 1 in 20 deaths.
On average, one person in the U.S. dies of a stroke every 4 minutes.
These shocking figures are the reason that stroke is a hot area of medical research. Understanding the risk factors and how different types of stroke affect different people is essential and potentially life-saving information.
Types of stroke
There are three main types of stroke:
Ischemic stroke: This is the most common form, accounting for 87 percent of all strokes. It occurs when there is an obstruction in a blood vessel supplying blood to the brain.
Hemorrhagic stroke: Occurs when a weakened blood vessel ruptures, releasing blood into the brain. The most common cause of hemorrhagic stroke is high blood pressure(hypertension).
TIA (transient ischemic attack): Sometimes called a ministroke, TIAs are caused by a temporary clot and are regarded as a warning sign.
As investigators delve into the growing pool of data, they have discovered that the risks for stroke types vary between subsets of individuals. These differences have sparked a wealth of research.
Overweight, obesity, and stroke
A recent study, published in Neurology, investigated the prevalence of different stroke types in overweight and obese women.
The investigation used data from 1.3 million women in the United Kingdom with an average age of 57. Over the course of the 12-year study, 20,549 had a stroke.
Among women with a healthy weight – body mass index (BMI) 22.5-25 – 0.7 percent had an ischemic stroke and 0.5 percent had a hemorrhagic stroke.
Within the 228,274 obese women (BMI 30 or above), 1 percent had an ischemic stroke and 0.4 percent had a hemorrhagic stroke.
“We found that the risk of ischemic stroke […] is increased in overweight and obese women. By contrast, the risk of hemorrhagic stroke […] is decreased in overweight and obese women.
Our findings add to the growing body of evidence that different types of stroke have different risk profiles.”
Gillian Reeves, Ph.D., University of Oxford, U.K.
The findings show that for every five-unit increase in BMI, the ischemic stroke risk increased by 21 percent. For hemorrhagic stroke, every five-unit increase in BMI gave a 12 percent decrease in risk.
Adding to our knowledge of stroke
Combining results from a host of previously published studies, the U.K. researchers were able to add rigidity to their findings. They showed that, globally, risks associated with excess weight are significantly stronger for ischemic than hemorrhagic stroke.
An accompanying editorial, written by Dr. Kathryn Rexrode, MPH, at Brigham and Women’s Hospital in Boston, MA, added a note of caution when interpreting the data. The findings do not mean that obese women have a reduced risk of stroke overall.
Dr. Rexrode writes:
“Higher body mass index, or BMI, was associated with increased risk of total stroke in every category and the number of ischemic strokes was higher than the number of hemorrhagic stroke in every category. So higher BMI was not associated with protection or reduced risk of total stroke. Obesity is a substantial stroke risk factor for all ages and even more alarming for young adults.”
The current findings add to the wealth of knowledge currently being generated about the risk factors for stroke and how it can be better managed.
Written by Tim Newman