"People ask, How did you get in there? What they really want to know is if they are likely to end up in there as well. I can't answer the real question. All I can tell them is, It's easy." Thus begins Susanna Kaysen's notable 1993 memoir of her two-year sojourn in a mental hospital. "There" in this case is McLean, a private psychiatric hospital near Boston, Massachusetts, where Kaysen, then a teenager, was sent following a suicide attempt. Twenty years in the mulling-over stage, Kaysen's book of her experiences, Girl, Interrupted, found an eager audience upon publication, and with the advent of a movie adaptation in 1999 starring Winona Ryder, the book and its message reached an even wider audience, rising to the top of the charts of most popular books on college campuses around the country. The popularity of Kaysen's book, which some compare to Sylvia Plath's The...