Elton John may have been friends with the late Michael Jackson for a while, but according to his new memoir, Me, things changed as the years went on.

As the British singer writes in an excerpt published by The Independent, “I’d known Michael since he was 13 or 14. He was just the most adorable kid you could imagine. But at some point in the intervening years, he started sequestering himself away from the world, and away from reality the way Elvis Presley did.”

“God knows what was going on in his head,” he added, “and God knows what prescription drugs he was being pumped full of, but every time I saw him in his later years I came away thinking the poor guy had totally lost his marbles. I don’t mean that in the light-hearted way. He was genuinely mentally ill, a disturbing person to be around. It was incredibly sad.”

In the book, Elton talks about a dinner party he once hosted, which Michael had been invited to. He recalled that the Thriller singer dismissed himself from the table and they later found him with their housekeeper and her 11-year-old son.

“For whatever reason, he couldn’t seem to cope with adult company at all,” Elton wrote.

Read more of these crazy revelations at The Independent.