I am no expert, but I get the impression that chronic diseases—and neurodegenerative diseases in particular—cannot be cured by a molecular drug targeting a single biological process.

This is largely because, in the case of Alzheimer’s, Parkinson’s, and many other neurodegenerative conditions, the brain has undergone atrophy: neurons and glial cells have died off, and the bulk of the brain cannot regenerate, even if a miracle were to restore healthy conditions (with the possible exception of a tiny area like the hypothalamus; however, one should not expect septuagenarians to possess a vast reservoir of stem cells ready to generate new cells).

I place more hope in regenerative strategies, such as those aimed at reverting specialized cells (particularly glial cells) to a more youthful state while preserving their specialization.