"The research evidence suggests that there are differences when the psychosis is seen as a whole syndrome when compared with schizophrenic syndromes. The literature then is ambiguous about whether these prolonged psychoses are related specifically to LSD (that is an LSD psychosis) or to an
occurrence of Schizophrenia."
http://www.maps.org/research/abrahart.html

"Well, there's the study by Sidney Cohen which was cited here recently, Journal of Nervous and Mental Disease, 130, 1960. The following is from Jay Stevens' Storming Heaven: "Cohen surveyed a sample of five thousand individuals who had taken LSD twenty-five thousand times. He found and average of 1.8 psychotic episodes per thousand ingestions, 1.2 attempted suicides, and 0.4 completed suicides. 'Considering the enormous scope of the psychic responses it induces,' he concluded, 'LSD is an astonishingly safe drug.""'

Because the "LSD psychosis" is not distinguishable from non-drug-induced psychosis, we have reasonable evidence to conclude that LSD was not the sole cause of psychosis. Instead, it would seem that the drug brought on the problems in vulnerable individuals. Interestingly, the rate of parental alcoholism was found to be much higher in LSD patients than in other patients or in the general population by one study (Vardy and Kay, Arch-Gen-Psych, 1983 40(8): 877-83).

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