Ketamine and Psychotic Symptoms

Image: Effect of ketamine vs. psychosis on the prediction error response. Retrieved from Cambridge Neuroscience: Dr. Phil Corlett
"[The] world is ... what we make of it. Once our mould for world making is formed it most strongly resists change. The psychodelics (sic) allow us, for a little while, to divest ourselves of these acquired assumptions and to see the universe again with an innocent eye." (Osmond 1957)

Ketamine and psychotic symptoms

"Both ketamine and PCP block NMDA receptor transmission in mammalian neurons. This observation, coupled with psychopathology induced by ketamine in healthy volunteers and patients with schizophrenia, led to the development of NMDA hypofunction model of schizophrenia.
Single doses of ketamine induce a transient psychotic state in healthy volunteers characterised by perceptual aberrations, delusion-like ideas, thought disorder, blunted affect, and emotional withdrawal.
Particularly relevant to the present model, ketamine affects the intensity and integrity of the sensory experience. For both auditory and visual perception, acuity is increased and background stimuli become more salient.
In addition to impairing NMDA transmission, ketamine binds to D2 dopamine receptors and induces striatal dopamine release in healthy volunteers. The magnitude of this release correlates with the intensity of ketamine-induced psychosis. However, haloperidol, and an anti-psychotic which affords high D2 receptor blockade, fails to reverse the psychotomimetic effects of ketamine. On the other hand, compounds which reduce pre-synaptic glutamate release do attenuate the psychotic symptoms as does blockade of AMPA receptor function in experimental animals."

- pp. 519 - 520, From drugs to deprivation: a Bayesian framework for understand models of psychosis by Corrlett, P R; Firth, C D, P C in Psychopharmacology (2009) 206: 515- 530

Ketamine, Psychosis, Schizophrenia, addiction, delusion