The late Pink Floyd star SYD BARRETT retired from the music scene after LSD caused an "explosion" in his head, according to his sister Rosemary.
The singer left the band in 1968 and had a fleeting solo career before eventually quitting the music scene altogether.
And his sister claims it was his experimentation with acid that turned him into a recluse.
She says, "People ask me why Syd withdrew and I think it was a combination of too much LSD and a very eccentric creative brain.
"If you're very tired and put a load of acid into the mix you've got chaos haven't you? It was all very nasty but it was inevitable. When you put those three factors together you are going to have an explosion aren't you?"
Barrett died in 2006 aged 60 from pancreatic cancer.