Abstract
Systematic scientific interest in psychedelic substances has a tradition of about
100 years. Numerous human experimental studies have confirmed the existence of a common
nucleus of experiences in hallucinogen-induced states and the acute stages of schizophrenic
psychoses. However, the degree of resemblance between endogenous and drug-induced
psychotic states has been an issue of controversial debate. After the scheduling of
psychedelics in the 1960s, human research became highly restricted worldwide and scientific
interest in this field faded. The debate about the appropriateness of the psychedelic
state as a model for endogenous psychosis therefore seemed to have little practical
relevance. Currently there is a revival of scientific interest in human experimental
psychedelic research. Consequently, the appropriateness of hallucinogen-induced states
as models for psychosis needs to be reappraised. The arguments for and against are
summarized in this paper. In conclusion, the drug-induced model psychosis is shown
to be a useful model for acute psychotic stages, but not for the nosological entity
schizophrenia.
