You could give my favorite novel a try. It's "Flowers for Algernon" by Daniel Keyes. It's a book, set in the 60's, about a mentally disabled man named Charlie Gordon who is picked to undergo a revolutionary new medical procedure involving transplanting stem cells into the brain as a means to improve mental capability. The book follows his adventures, via journal entries he writes, as he increases in mental ability, eventually becoming a super genius. His best friend throughout the book is a lab mouse named Algernon, whom he meets at the lab where his procedure is preformed.

I won't spoil the ending, but grab a box of tissues. The book tends to be very heavy on the emotions, being that it deals with heavy subject matter.