Addiction Biology
October 1, 2002
Torsten Passie, Juergen Seifert, Udo Schneider et al.
465 citations
Psilocybin, the main psychoactive alkaloid in certain mushrooms found worldwide, is increasingly abused as a hallucinogenic drug. Although it was used experimentally in medicine during the 1960s, pharmacological information about it remained scarce until recently. This review compiles all available pharmacological data on psilocybin, addressing the ongoing abuse potential and the need for comprehensive knowledge.
Neuropsychobiology
January 1, 2005
Torsten Passie, Matthias Karst, Birgitt Wiese et al.
35 citations
The first neuropsychological study of the S-enantiomer of ketamine, a noncompetitive NMDA antagonist, found that low and high subanaesthetic doses produced only nonsignificant impairment on most cognitive tasks in 12 healthy male volunteers. However, tasks involving divided and sustained attention, along with objective and subjective psychopathology scores, showed significant impairment that increased with dose. These results suggest that ketamine's effects on attention may model aspects of schizophrenia.
Journal of Psychopharmacology
January 1, 2003
Torsten Passie, Matthias Karst, Mathias Borsutzky et al.
27 citations
The NMDA neurotransmitter system's role in psychoses is not fully understood, but NMDA antagonists like phencyclidine and ketamine induce psychotic states similar to schizophrenia. Binocular depth inversion, a visual illusion impaired in psychotic states, was tested in 12 healthy male volunteers using stereoscopic pictures of natural and artificial objects. Two subanaesthetic doses of the psychotomimetic S-enantiomer of ketamine were compared with placebo. Despite dose-dependent subjective and objective psychopathology, no significant impairment of binocular depth perception occurred with (S)-ketamine. The findings suggest implications for memory, perception formation, and bottom-up processing in ketamine model psychosis and schizophrenia.
Psychology Health & Medicine
November 27, 2012
Torsten Passie, Udo Schneider, Mathias Borsutzky et al.
7 citations
The binocular depth inversion test (BDIT) measures a visual illusion in which implausible objects, such as a hollow face, are perceived as normal and convex. This illusion is common and influenced by familiarity, with cognitive factors overriding binocular disparity cues. The internal mechanism balancing top-down and bottom-up perceptual processes appears disturbed in pro-psychotic states. In this pilot study, patients with anxiety disorders scored significantly higher on the BDIT than matched controls, in a range comparable to pro-psychotic conditions. The findings suggest anxiety patients may have abnormalities in central perceptual processing, top-down processing, and reality testing similar to those seen in pro-psychotic conditions.
Schizophrenia research
December 1, 2006
Dagmar Koethe, Christoph W Gerth, Miriam A Neatby et al.
In people with schizophrenia, in the prodromal phase, and in healthy volunteers given synthetic delta-9-tetrahydrocannabinol (THC), performance on a test of visual information processing (the Binocular Depth Inversion Illusion Test) was similarly impaired, and all three groups differed significantly from healthy controls who received no drug. On the Brief Psychiatric Rating Scale, the THC-treated group and the prodromal group did not differ significantly, while both differed from the schizophrenia group and from controls. The findings suggest that THC-induced altered states can model psychotic disorders, especially their prodromal states, and help explain the pro-psychotic effects of high-THC cannabis.