Now I don't claim to know a lot about LSD as it was one of the few drugs I never tried 30 years ago that along with coke, crack, heroine or any other street or "designer" drugs. What I do know it seems acid did have a mental effect a lot of the artists back then. Most notably Brian and Dennis Wilson, Peter Green, Syd Barrett causing severe mental issues after multiple trips and on the following artists , but long term will never be know as they never made it out of their early to mid twenties dying from drug over doses Jim Morrison, Jimi Hendrix, Brian Jones, Graham Parsons, Janis Joplin and many others from back then. Also seemingly John too, but not to the point of say Brian Wilson, but it did seem to alter his personality some. The weaker pysche, the more pronounced the permanent effect was.