A genetic component?
With Alzheimer's, there is a genetic component that scientists and researchers are still trying to understand. For Alzheimer's to develop as a result of a genetic mutation, it means that there are abnormal precursors that aid in this buildup of amyloid protein, and also for the tau protein to tangle.
Based on this, researchers are trying to understand how Alzheimer's can be prevented. If those with a family history of Alzheimer's are aware that they inherited the gene, they can look at their options. But, for the most part, the onset is inevitable and they can only delay its symptoms for so long.