A gene variation that helps people live to a ripe old age also appears to preserve memory and thinking power
The "longevity" gene alters the size of fatty cholesterol particles in the blood, making them bigger than normal.
This stops them causing the fatty build up in blood vessels that is linked with brain impairment, and deadly strokes and heart attacks, Neurology reports.
The study involved nearly 300 Ashkenazi Jews in their 70s, 80s and 90s.
The nonagenarians who possessed the longevity gene were twice as likely to have good brain function than those who did not have the gene variant.
Their performance on tests of memory and concentration was far superior.
Also, those who had reached a century were three times more likely to have the longevity gene variation than their 70-year-old counterparts.
Lead researcher Nir Barzilia, director of the Institute for Aging Research at Albert Einstein College of Medicine in New York, said the same gene variation might also protect against Alzheimer's dementia.
How to live to a ripe old age without losing your marbles
Longevity gene also protects memory, cognitive function