Bibliotherapy: How Books Can Treat Anxiety & Depression

I've always known that reading books for pleasure and relaxation has been helpful in making me a better, more well-rounded person. Additionally, reading is both entertaining and educational. So, the benefits of reading is no surprise to me. But can reading truly be used to treat or even cure depression & anxiety?

The term "Bibliotherapy" is a new one to me. I came across "Bibliotherapy" in an article titled Bibliotherapy: How Books Can Treat Anxiety, Depression recently published on the Huffington Post website. According to the article Bibliotherapy: How Books Can Treat Anxiety, Depression:

This is the idea behind Bibliotherapy, a supposed cure for depression and anxiety being implemented by author Alain De Botton at his London company, The School of Life. De Botton is the author of "How Proust Can Change Your Life," a book that blends literary fiction and self-help. He says academics "could never forgive [him]" for making Proust accessible, but personally believes books are more than works of art to be admired.

Whether or not a book can single-handedly tackle a person's depression is difficult to determine, but positive thinking has been proven to help. According to a Psychology Today article titled "Depression Doing the Thinking," "One of the most powerful actions you can take in combating depression is to understand how critical the quality of your thinking is to maintaining and even intensifying your depression—and that the quickest way to change how you feel is to change how you think." The article goes on to explain how negative thoughts can enter one's mind subconsciously, and therefore seem more raw or true to the depression sufferer than their own moods and feelings. 

Bibliotherapy is an interesting concept/therapy. I wonder how successful it is in treating those suffering from depression & anxiety?