To cope with Trump's erratic behavior, his chief of staff secretly bought a book written by mental health experts who scrutinized Trump's decisions: book

• Trump's former chief of staff consulted a book to help him cope with the former president's erratic behavior.
• The book features examinations of Trump's behavior from 27 mental health professionals.

Trump's former chief of staff John Kelly purchased a book to learn how to cope with the former president's erratic behavior, according to an upcoming book written by two journalists.

Kelly bought the book "to understand the president's particular psychoses," according to a report from The Guardian, which has obtained an advance copy of the upcoming book from journalists Susan Glasser and Peter Baker.

The book — called The Dangerous Case of Donald Trump — features examinations of Trump's behavior from 27 psychiatrists and mental health professionals.

Kelly "consulted it while he was running the White House, which he was known to refer to as 'Crazytown,'" Glasser and Baker's book says.

The editor of The Dangerous Case of Donald Trump described the book as a collection of "observations of a person's patterns of responses, of media appearances over time, and from reports of those close to him."

"Indeed, we know far more about Trump in this regard than many, if not most, of our patients," Yale psychiatrist Bandy Lee said of the book. "Nevertheless, the personal health of a public figure is her private affair – until, that is, it becomes a threat to public health."

Glasser and Baker write in their upcoming book, slated to be released to the public later this month, that The Dangerous Case of Donald Trump helped Kelly navigate the White House.

"Kelly told others that the book was a helpful guide to a president he came to consider a pathological liar whose inflated ego was in fact the sign of a deeply insecure person," the book says.

Senior officials serving in the White House agreed with Kelly, Glasser and Baker reported in their book.

"I think there's something wrong with [Trump]," one senior official said in the book. "He doesn't listen to anybody, and he feels like he shouldn't. He just doesn't care what other people say and think. I've never seen anything like it."