Psychedelics can dissolve more than the mind's conceptual prisons, perhaps much more of the mind than one would like. How did the hippie-era stereotype of the burned out acid head disappear so quickly from popular culture?

Kary Mullis is known to have used a lot of it and discovered PCR while off psychedelics. There's also the famous Hoffman's bycicle day. The stereotype is just that, and might be a result of lack of mental stimulation rather than LSD abuse, which is possibly the safest drug in terms of toxicity.