Ninety-seven-year-old Scott Hughes and her identical twin sister Virginia were always close. When Virginia started having trouble with her memory and thinking, Scott knew something wasn’t right. Virginia was later diagnosed with. “It was heartbreaking because she was so outgoing and loving,” Scott Hughes told CBS News. “She wasn’t going to be who she was before. And that is tragic to see in someone you love.” With one twin having Alzheimer’s and the other healthy, researchers at Duke Eye Center who are studying the link between eye and brain health thought the sisters were a good case to examine. They took images of their eyes and discovered the twin with Alzheimer’s disease had significantly decreased blood vessel density in the retina. That finding spurred a new study of more than 200 people.