For adult children, understanding that their parents may no longer be able to care for themselves can be quite a shift in their thinking. For as long as they can remember, their parents have been these pillars of independence. They raised them when they were children, and they certainly always seemed like they could take care of themselves. They helped the adult children grow up and learn how to navigate the world, and it's strange to see their abilities decline to the point that they may now need the assistance they once provided.
However, for many families, this is a reality. A disorder like Alzheimer's Disease can make it so that even physically healthy parents cannot take care of themselves. A stroke or a similar issue can limit physical abilities so that parents who still have a firm mental grasp on the world need daily assistance with even simple tasks. For some parents, both these physical and mental issues collide and they need care on both fronts. Every situation is unique.