“These ‘silent strokes’ are more significant than the name implies, because they have been associated with an increased risk of falls and impaired mobility, memory problems and even dementia, as well as stroke,” said study expert Joshua Z. Willey. The research was also completed at the Univeristy of Miami in Florida. “Encouraging older people to take part in moderate to intense exercise may be an important strategy for keeping their brains healthy.”

The study involved 1,238 people who had never had a stroke. Participants completed a questionnaire about how often and how intensely they exercised at the beginning of the study and then had MRI scans of their brains an average of six years later, when they were an average of 70 years old.

A total of 43 percent of the participants reported that they had no regular exercise; 36 percent engaged in regular light exercise, such as golf, walking, bowling or dancing; and 21 percent engaged in regular moderate to intense exercise, such as hiking, tennis, swimming, biking, jogging or racquetball.

The brain scans showed that 197 of the participants, or 16 percent, had small brain lesions, or infarcts, called silent strokes. People who engaged in moderate to intense exercise were 40 percent less likely to have the silent strokes than people who did no regular exercise. The results remained the same after the researchers took into account other vascular risk factors such as high blood pressure, high cholesterol and smoking. There was no difference between those who engaged in light exercise and those who did not exercise.