My first taste of acid was at about 16 and pretty inconclusive. But I have a friend, a hippie tattoo guy, who was raised by hippie tattoo parents. His father offered him his first taste of acid at 10, and after that went well he started having it regularly, often without adult supervision.
Now, this was a pretty loose family, really no rules or anything. At the time they lived in Goa with no power or plumbing, and ran their tattoo operation off car batteries. Anyway, one day this ten-year-old takes a hit of acid and walks down to the Ganges to watch people burning their dead. He parked himself in a spot where he could get a really good view of a particularly fancy funeral pyre setup, just as they were lighting the fire. At this point he's starting to peak pretty hard. The family is milling around the deceased man, pretty much ignoring the tripping ten-year-old hovering nearby. The fire quickly overwhelms the fabric dressings and a wave of flame comes and goes; as it settles the body starts smoldering.
At this point my friend is entirely focused on the man's head. The hair has been burned away and the skin is tightening and darkening. Suddenly it gives way, breaking apart into animated black ornamental fractal spirals curling around the face. Next the fat starts to boil, becoming infinitely intricate churning golden ornament, morphing and crawling over the face in rapid motion, a mask of living jewelry. Finally the fats dry up and give way to layers of white spiraling Art Neuveau embellishments.
Ever since he told me this story I've wondered how it must have effected him as an adult. No doubt there were many other occasions as well. He is now a brilliant and successful artist, who specializes in (among other things) jeweled skulls. Other artists draw them too, but his have far more life and vitality, more personality. As far as how all that acid at a young age might have effected him outside his art, that's impossible to say- so many things about his upbringing were just completely outside the normal definitions. Acid or not, he was destined to be a bit different.
And yes, he still trips. He's now I'm his late forties.