Last July, Steven Miller, a university librarian, came across an article about a set of neurological conditions he had never heard of called autistic spectrum disorders. By the time he finished reading, his face was wet with tears. "This is me," Mr. Miller remembers thinking in the months of eager research that followed. "To read about it and feel that I'm not the only one, that maybe it's O.K., maybe it's just a human difference, was extremely emotional. In a way it has changed everything, even though nothing has changed." Mr. Miller, 49, who excels at his job but finds...