Two years ago, the novelist John Green was unable to control his thoughts. His mind played relentlessly over the same fears and anxieties. At times, he couldn’t focus enough to read a menu or follow the plot of a television show, much less write a book.
It was a terrifying feeling, but a familiar one. Mr. Green, the author of the best-selling novel “The Fault in Our Stars,” has struggled with severe anxiety and obsessive compulsive disorder for about as long as he can remember. He keeps it in check with medication and therapy, but every once in a while, it consumes him.
“I couldn’t escape the spiral of my thoughts, and I felt like they were coming from the outside,” Mr. Green said in an interview.
When he recovered after a few months, he started writing “Turtles All the Way Down,” a wrenching and revelatory novel that provides a window into what it’s like to live in constant fear of your own mind.
“Coming out of that, it was difficult to write about anything else,” he said. “The topic demanded itself.”
“Turtles All the Way Down,” published on Tuesday, Oct. 10, is Mr. Green’s most personal book yet. Its narrator, Aza Holmes, is a 16-year-old girl in Indianapolis who wrestles with anxiety and obsessive thought spirals. Aza has normal teenage preoccupations, and struggles to navigate the rites of adolescence: dating, fretting about college, calming her overbearing mother, appeasing her demanding best friend.
But she is also frequently overcome by extreme dread. She’s certain that she’s contracted an intestinal bacteria that can be fatal. She worries that a cut on her finger, which she presses on uncontrollably, will become infected and kill her. She starts drinking hand sanitizer. She often wonders if she is fictional: If she can’t direct her own thoughts, who is really in control?
“Turtles All the Way Down” is an emotionally fraught project for Mr. Green, whose young adult novels are beloved for their quirky humor and sharp, sensitive teenage protagonists. His books have more than 50 million copies in print worldwide; two have been adapted into films. Mr. Green, 40, who lives in Indianapolis with his wife, Sarah Urist Green, and their two children, Henry, 7, and Alice, 4, is one of the publishing industry’s biggest stars, and over the past decade, he and his brother Hank have built an online video business with 16 educational shows that have collectively drawn more than two billion views on YouTube.
Mr. Green’s onscreen persona for YouTube shows like “Crash Course” is ceaselessly energetic and positive. But he has wrestled with weighty subjects in his books — his young characters battle illness and mortality, depression and bullying — and has occasionally addressed his own mental health issues. In a video posted this summer, he discussed how difficult it is to talk about his experience of obsessive compulsive disorder, in part because language so often fails to capture abstract feelings.