My best friend some years ago, actually decades ago, knew and played with him. He said they regularly shot up heroin together. Of course he’s going to deny it - it would be bad for publicity.
Maybe, but it's hard to imagine a heroin addict living to age 83, and still in good enough physical condition to do nearly 100 performances in 2024 -- in 33 US states, 4 Canadian provinces, plus six European countries.
So, I don't know what fuels all that energy but doubt if it's heroin.