Flowers for Algeron by Daniel Keyes
1960 Hugo Award for best short story
1966 Nebula Award for best novel
Charley is a 32 year old man with an IQ of 68. He has a job and his own place. And he is desperate to learn to read. He's taking a course at a college for the retarded. His teacher is so impressed with his enthusiasm she submits him as a candidate for a experiment. He has brain surgery that increases his IQ tremendously. But once his IQ eclipses that of the scientists trying to cure retardation, he realizes the boost in brain power is only temporary.
This is a wonderful book. It began life as a short story and was so popular, it was rewritten as a novel. It's written as a journal the doctors ask Charley to keep so they can monitor his progress. In the beginning he writes like a 6 year old. But as his IQ goes up, so do his abilities. But then everything begins to regress. It's a sad story. It actually brought tears to my eyes at the end.