"Dr. Kawas’s group has found that some people who are lucid until the end of a very long life have brains that appear riddled with Alzheimer’s disease. In a study released last month, the researchers report that many of them carry a gene variant called APOE2, which may help them maintain mental sharpness.
Dr. Nir Barzilai of the Albert Einstein College of Medicine has found that lucid Ashkenazi Jewish centenarians are three times more likely to carry a gene called CETP, which appears to increase the size and amount of so-called good cholesterol particles, than peers who succumbed to dementia."