8 percent of the participants had the silent lacunar infarctions, small areas of damage to the brain seen on MRI that never caused obvious symptoms. They occur when blood flow is blocked in one of the arteries leading to areas deep within the brain, such as the putamen or the thalamus.

By the end of the study, an additional 1.6 percent of the participants had developed 'silent' strokes, said an UNSW statement.

People with high BP were 60 percent more likely to have silent strokes than those with normal blood pressure. Also, people with another type of small brain damage called white matter hyperintensities were nearly five times as likely to have silent strokes as those without the condition.

The study was published in Neurology journal.