A new study has found that people over 80 who keep their minds sharp have a genetic advantage. These individuals are significantly less likely to carry the APOE4 gene, which is most associated with Alzheimer's disease risk, even compared to other healthy seniors of the same age. The researchers also identified higher levels of a protective gene variant in this group that provides additional protection. Together, these genetic factors help explain why some people age with remarkably youthful minds and avoid the cognitive decline that affects most older people. The findings indicate that genetic predisposition plays an important role in preserving cognitive function in old age.