More than 10 percent of the adult population could unknowingly suffer from silent strokes that damage the body without producing any telltale signs, according to a study published by BU researchers.
MRI scans from 2,040 healthy Framingham Offspring Study participants showed 10.7 percent of them had unknowingly suffered from silent, asymptomatic strokes, likely caused by brain-based blood clots, said study co-author Sudha Seshadri, a BU assistant professor of neurology.
“The MRIs do not look different from what we would see if they really had a clinical stroke, but we followed them very carefully, and they never had any symptoms,” Seshadri said.
The study was published in Stroke: Journal of the American Heart Association June 26 as a continuation of the Framingham Heart Study, a broad-based survey researchers began in 1948 to identify the risk factors, determinants and outcomes of cardiovascular disease.
Since it began 60 years ago, the study has gone on to examine the descendants of the original participants who signed up in 1948. But even after following participants’ health for their entire lives, researchers never noticed the stroke symptoms, Seshadri said.
Though the signs of these silent strokes remained hidden, their side effects were not so subtle, she added.
“When we do detail testing, as it looks, people with silent [strokes] tend to not do quite as well as people without them,” she said. “It may not be completely without symptoms.”
The extent of damage depends on where the silent stroke hits, Seshadri said.
“If it is in an expressive area, like in the middle of the speech center or in the part of the brain that controls the hand, then the person would probably develop a weakness of the hand or a speech problem,” she said. “Some of these are so small or so deep, though, that they don’t show up immediately.”
Since having a silent stroke increases the risk of having a clinical stroke as well as progressive brain damage, paying attention to the well-known risk factors is advisable, Seshadri said.
Some stroke risk factors, such as genetics, age and gender, cannot be helped according the American Heart Association’s website. Still, people can reduce their risk of suffering a stroke by choosing healthy lifestyles, Seshadri said.
High blood pressure is the single most important risk factor for silent strokes, followed by diabetes and obesity, health experts say.
“Knowing your numbers for blood pressure, cholesterol and weight is the key to preventing stroke,” American Heart Association/American Stroke Association spokeswoman Angela Minardi said. “By making a lifestyle change, you can modify your risk, such as quitting smoking, being physically active or reducing alcohol intake.”