Feeling faint, dizzy or lightheaded when standing up might mean you’re at greater risk of stroke or dementia in older age, according to a new study.

Dizziness can be caused by a sudden drop in blood pressure called orthostatic hypotension, researchers said, and it’s this drop among middle-aged people which has been linked to both illnesses.

A major study involving 11,700 people found those with orthostatic hypotension had a 54% higher risk of developing dementia and twice the risk of ischemic stroke, which is caused by a blood clot in the brain, than those who did not have it.

Lead author Andreea Rawlings of Johns Hopkins Bloomberg School of Public Health said: “Orthostatic hypotension has been linked to heart disease, fainting and falls, so we wanted to conduct a large study to determine if this form of low blood pressure was also linked to problems in the brain, specifically dementia.”

The study involved 11,709 people with an average age of 54 who were followed for an average of 25 years and met with researchers up to five times over the course of the study. None had a history of heart disease or stroke at the beginning of the study.

During the initial exam, participants were screened for orthostatic hypotension. They were instructed to lie down for 20 minutes and then stand up in a smooth, swift motion. Blood pressure was taken five times upon standing.

Researchers found 552 participants had orthostatic hypotension at the start of the study. All participants were monitored throughout the study for dementia and stroke, during which 1,068 people developed dementia and 842 people had an ischemic stroke.

Researchers found those who had orthostatic hypotension at the beginning of the study had a 54% higher risk of developing dementia than those who did not. Those with orthostatic hypotension also had twice the risk of having an ischemic stroke. Researchers said there was no association with bleeding strokes.

“Measuring orthostatic hypotension in middle-age may be a new way to identify people who need to be carefully monitored for dementia or stroke,” said Rawlings. “More studies are needed to clarify what may be causing these links as well as to investigate possible prevention strategies.”