Even in the most recent, supposedly well-researched books about FDR, there is virtually no mention of his medical condition, status, or treatment. He needs to rest a lot, but you never hear that he was visited by a doctor several times a day, and often travel to Bethesda Naval Hospital and other hospitals and clinics, some out of town, secretly. Perhaps this is because it took a physician to sort out the available, published facts, and discover new ones by research and interviews of the involved persons still alive today.
The thesis is that FDR died of cancer, or complications therefrom. Yes, he had a "terrible headache" and, no doubt, a brain hemmorage, but why has until now never been thoroughly documented. It's a great medical detective story, with the subtext being that dozens and hundreds of people participated in the cover-up (in public, FDR was as healthy as a man under the circumstances could be, supposedly). Yeah, right.
Of course, like many well-researched history books, the most interesting parts are the "other" things you can learn about the subject or topic that the author managed to discover along the way.
But were it not for this not-so-silent, but non-public (albeit self-serving) conspiracy of silence regarding FDR's actual health condition, history might have played out drastically differently than it actually did. Whether or not we would have been better off is a question for the political sphere, and each will no doubt have his or her own opinion, but one thing is clear: what FDR endured in his self-appointed task of sheperding this country through World War II is both humbling and amazing.