Hi Seeker,
you said
JWs are taught that the end is right around the corner. So in their mind, the age they are now is as old as they will ever get. To think otherwise is to lose faith in the teachings of the Society. So what happens as the years go by and no end is in sight and their bodies begin to break down? I think what is happening inside them is a psychological struggle. They perceive that their bodies are betraying them, failing in just the sort of way they thought could never happen. Yet they cannot consciously admit this to themselves, for that would be tantamount to accepting that the Society got it wrong, and that cannot be. So without consciously realizing it, they are open to anything, absolutely anything, that will restore their health. They want to deny the aging process somehow, to keep their hope alive.
You are absolutely right. I know of many people like this in the organization. They just cannot believe that the society got it wrong.