"Counter-Clock World" by Philip K. Dick (1967)
"'What a thing to look forward to: childhood. Being a baby again, being helpless, waited-on. Every day I try to be more grown up; I fight all the time against it, the way ladies used to fight being old, getting middle-aged, fat, with wrinkles. Well, I don't have to worry about that. But see, Sebastian will be an adult when I'm still a child, and that's good; he can be my father and protect me. But you're the same age as I; we'd just be children together, and what's in that?'"
"Counter-Clock World" is an expanded version of a story that first appeared in Amazing Stories. It was published during a very productive period in PKD's career, between "The Unteleported Man" (a.k.a. Lies, Inc.) and "The Three Stigmata of Palmer Eldritch."
In a future 1998. a phenomenon known as "The Hobart Phase" is making time run backward. People age from death to birth, they disgorge meals they've already eaten, and they unsmoke packs of cigarettes. In the midst of this phenomenon Thomas Peak, a messiah figure, returns to life. Uncertain as to the true nature of his message, several factions compete to acquire him.
It's a really short book, so I can't hold too much of a grudge against it, but PKD wrote much better. The biggest problem with this book is causality, because aside from very trivial matters the world of "Counter-Clock World" seems to be moving firmly forward. And how could it not? Otherwise it wouldn't make sense as a story, and it would have been even less satisfying than it is.
Even without the causality issue, this book is a disappointment. There is no real climax to the story, and no adequate resolution to the characters' dilemmas is ever reached. The love triangle (or perhaps I should say love quadrangle) at the center of the story seems forced, if not unlikely. To find paper-thin characters in a PKD novel is of course nothing unusual, but in this instance he fails to make them resonate within a larger, slightly surreal reality.
Completists will naturally seek this one out, but if you're new to PKD I could recommend a host of other, better written novels. Counter-Clock World just isn't very good.