How not to outlive our brains, and stop dying overhealthy

Medicine can extend the life of our bodies but not of our brains, which remain quite impermeable to drugs. Thus, we are harvesting generations of brainless old persons, who are out living their minds, because of dementia, alzheimer and the like.
The proper way to correct this is not to euthanise old people, but a braver path: to reduce the medical expenses in our society, so that we  stop becoming over-healthy, and our brain and body die together, peacefully and naturally.