Joey Ramone was diagnosed with schizophrenia at a young age and battled the illness all his life, the punk icon’s younger brother details in a new book.

In “I Slept With Joey Ramone: A Family Memoir,” out in December, Joey’s brother Mickey Leigh, who co-wrote the book with journalist Legs McNeil, chronicles how serious Ramone’s mental illness was.

After pulling a knife on Mickey and his mother as a teenager, Joey was admitted to St. Vincent’s Hospital for a month. The book excerpts the official report:

“The patient essentially sees himself with low self-esteem, as a combination of being both dangerous and in danger, approaching the unfamiliar with considerable caution and suspicion, frequently employing poor judgement in the process.

“His sense of self is of a passive, dependent person with ambivalent sexual identification, against which he is inclined to defend himself by means of distancing maneuvers to the point of estrangement . . .”

The report concluded: “His view of authority is markedly fearful, feeling his life to be in danger . . . The patient’s personality structure is consistent with diagnosis of schizophrenia, paranoid type with minimal brain damage (the latter probably of long-standing duration).”

The book says Joey was a huge admirer of Charles Manson, once saying of the mass-murderer, “He’s like Hitler, only cooler.” “It scared me,” Mickey says.

Fox Searchlight is reportedly in talks to turn the book into a movie. Rory Rosegarten, a former executive producer of “Everyone Loves Raymond,” snapped up the screen rights and rights to the Ramones’ music catalog after negotiating a deal with the Ramones’ mother, Charlotte Lesher, who died in 2007. Joey died of lymphatic cancer in 2001 at 49.