Cognitive, dissociative and psychotogenic effects of ketamine in recreational users
on the night of drug use and 3 days later
Authors: Curran H.V.; Morgan C.
Source: Addiction, Volume 95, Number 4, 1 April 2000 , pp. 575-590(16)
Publisher: Carfax Publishing, part of the Taylor & Francis Group
Aims. Recreational use of the N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine,
is increasing. The present study aimed to examine both the acute and residual effects
of this drug on cognitive function, dissociation and schizotypal symptomatology inrecreational users . Design and participants. A parallel group design was used to
compare 20 volunteers who reported having taken ketamine with 19 volunteers who reported
no consumption of ketamine on the relevant night (day 0). All 39 participants were
tested on day 0 and again 3 days later. On each test occasion a battery of tests
was administered which tapped a wide range of memory functions, attention, dissociation,
schizotypal symptomatology and mood. Findings. Groups were broadly matched for polydrug
use apart from ketamine. Acute effects on day 0 replicated previous laboratory studies
showing a broad spectrum of cognitive impairments following ketamine administration
as well as marked dissociative effects and schizotypal symptomatology. Three days
later, ketamine users had significantly higher scores than controls on both dissociation
and schizotypal symptomatology. On some cognitive measures there were no group differences
on day 3; however, on tests tapping semantic memory, the ketamine users showed persisting
impairments compared with controls. Conclusions. Ketamine appears to induce acute
and severe impairments of working, episodic and semantic memory as well as psychotogenic
and dissociative effects. Three days after drug ingestion, recreational users display
semantic memory impairment and dissociative and schizotypal symptomatology which
could reflect chronic or residual effects of taking the drug or pre-existing differences
in ketamine users.
Pomarol-Clotet, E., Honey, G.D., Murray G.K., et al (2006) Psychological effects
of ketamine in healthy volunteers. British Journal of Psychiatry, 189, 173-179.
Conclusions Ketamine does not reproduce the full picture of schizophrenia. The main
point of similarity concerns referential thinking. Phenomena resembling negative
symptoms are also seen but the distinction of these from the drug’s sedative effects
require further elucidation.