According to the American Stroke Association, silent strokes raise your risks for having a more damaging stroke and for developing dementia.

Published: December 26, 2023 | Updated: March 12, 2024

Not all strokes cause the classic symptoms: weakness in an arm or leg, difficulties speaking, or drooping of one side of the mouth or another part of the face.

You can have a stroke and not know it. These so-called silent strokes can result in no noticeable symptoms at all, but they are not harmless.

According to the American Stroke Association, silent strokes raise your risk for having a more damaging, symptomatic stroke in the future. They also increase your chance of developing dementia.

Most strokes — including silent strokes — are caused when a clot blocks a blood vessel in the brain. As a result, blood and oxygen don’t reach part of the brain, and nearby brain cells die.

“If the area of the brain that is damaged is small or happens to occur in a part of the brain that doesn’t control any vital functions like speech or mobility, the stroke can go unnoticed,” said Tamika M. Burrus, M.D., a neurologist and stroke specialist with Norton Neuroscience Institute.

The way most people find out they’ve had a silent stroke is when they happen to have brain imaging such as an MRI or CT scan for another condition and it reveals the small areas of the brain that have been damaged.

Even though someone having a silent stroke may not realize what has happened, these strokes may result in subtle issues with thinking and mobility. Though a single silent stroke may appear harmless, the neurological damage from several silent strokes can add up.

Silent strokes put you at greater risk for vascular dementia, which can cause memory issues, changes in the way you walk, getting lost in places familiar to you, trouble making decisions, laughing or crying at inappropriate times, and losing bladder or bowel control.

Silent strokes are surprisingly common. An estimated 1 in 4 people over age 80 have had at least one silent stroke. If you’ve had several silent strokes, you may begin noticing neurological issues such as having trouble remembering things or concentrating.

Risks for silent strokes — high blood pressure, smoking, heart disease and diabetes — are the same as risks for strokes that come with symptoms. Also, atrial fibrillation, an irregular heartbeat more common in people over 65, triples the chance of having a silent stroke.

If silent strokes are discovered, treatment can be the same as for people who have had more harmful strokes. This can include blood thinners and cholesterol medications to lower harmful low-density lipoprotein or LDL cholesterol, which can reduce the chance of future strokes.

Getting regular exercise, limiting alcohol intake, lowering your salt intake and following a diet that includes whole grains, fruits, nuts and vegetables can lower your chance of having any kind of stroke.

According to the American Stroke Association, for every symptomatic stroke, there are about 10 that are silent and occur without the person knowing it.

“Given what we know now about how common silent strokes are and that the harm from them can accumulate over time, adopting positive lifestyle changes becomes more important than ever,” Dr. Burrus said.