As a psychology nerd, I'm always excited to read a book that explores the human mind, especially in the area of disorders. I love reading challenges and haven't seen any this year that match this topic, so I thought "well, since I'm obsessed with it anyway, why not start a challenge for even more motivation to read what I love?" And hence, what you're reading.
Fiction or nonfiction, textbook or story—whatever you wish, as long as it fits the prompt.