What is strange about the period that Jimmie is stuck in from Dr. Sacks' perspective?

Jimmie G. is stuck in the year 1945. By all appearances, however, he remained functional in the military until leaving the Navy in 1965. His records indicate that he may have alcohol-related brain damage. After he leaves the Navy, he begins to downward spiral only then. But Sacks asks why Jimmie got stuck in 1945 and not 1965, when he actually started to become much worse. The strange thing is that one would expect Jimmie to get stuck in 1965, when his downward spiral began.