A study of about 470,000 older adults showed that much of the risk of Alzheimer's disease is linked to variations in a single gene called APOE. According to the results, approximately 71.5% to 92.7% of all Alzheimer's cases were associated with APOE3 and APOE4 gene variants. At the same time, the study indicated that variations in the APOE gene also explain almost half of all dementias in the monitored population. It is therefore a gene that has a very strong influence on the probability of developing Alzheimer's disease in later life. The authors analyzed the genetic data of hundreds of thousands of elderly people and tracked the incidence of dementia and Alzheimer's disease. The main finding is that differences in a single gene can explain most of the genetic risk of this disease in a population.