Decades ago, hundreds of nuns and priests made an extraordinary decision, agreeing to donate their brains upon death to science, hoping to help solve mysteries about Alzheimer’s and other diseases.

Now, a study that used their gifts is giving some clues. It reveals that high blood pressure late in life might harm the brain.

Autopsies on nearly 1300 older people, including about 640 clergy members, found more signs of damage and one of the hallmarks of Alzheimer’s disease in the brains of those with higher blood pressure than among those with pressure closer to normal, researchers report.