They turned these cells into two different kinds of brain cells and also examined brain tissue from specially bred mice carrying the human APOE genes. The experiments showed that neurons carrying APOE2 accumulated much less DNA damage than cells carrying APOE3 or APOE4. Since DNA damage builds up naturally with age, stronger repair systems could help brain cells survive for much longer. When the scientists exposed brain cells to radiation and another DNA-damaging treatment, APOE2 cells recovered much better than the others. For more health information, please see recent studies that high-fiber diet could help lower the dementia risk, and these antioxidants could help reduce dementia risk.