Comparison of Ketamine-Induced Thought Disorder in Healthy Volunteers and Thought Disorder in Schizophrenia

Abstract

These data suggest that ketamine-induced thought disorder in healthy volunteers is not dissimilar to the thought disorder in patients with schizophrenia and provide support for the involvement of the NMDA receptor in a cardinal symptom of schizophrenia.

Clinical and Sensorimotor Gating Effects of Ketamine in Normals

“…Adler et al (1998) have quantified thought disturbance more thoroughly by means of more sensitive instruments and found significant increases. Furthermore, the ketamine-induced thought disorder scores did not differ from scores in stable schizophrenics (Adler et al 1999).…”

“…PCP and ketamine bind to the PCP site in the channel of the NMDA receptor complex, resulting in noncompetitive inhibition of NMDA type neurotransmission (Javitt and Zukin 1990). This induces a transient state in normals characterized by positive and negative symptoms and cognitive dysfunction which is similar to what is commonly observed in schizophrenics (Luby et al 1959;Davies and Beech 1960;Bakker and Amini 1961;Allen and Young 1978;Krystal et al 1994;Malhotra et al 1996;Adler et al 1999). Schizophrenics in remission experience a resurgence of symptoms characteristic of their decompensation when given ketamine (Ban et al 1961;Itil et al 1967;Lahti et al 1995;Malhotra et al 1997).…”

Effects of Ketamine in Normal and Schizophrenic Volunteers

“…With respect to hallucinations, the NVs experienced mostly perceptual changes, but in more than 70% of patients the positive symptoms included previously experienced symptoms such as hallucinations and delusions. Others have also reported the similarity between normal and SVs in positive symptoms with ketamine (Adler et al 1999). Thus, ketamine appears to induce hallucinatory and delusional symptoms along a gradient of intensity.…”

Effects of the NMDA Antagonist Ketamine on Task-Switching Performance: Evidence for Specific Impairments of Executive Control

“…NMDA antagonists are known to mimic the neurobehavioral correlates of schizophrenia in healthy humans. For example, Adler et al (1999) found thought disorders in ketamine-treated healthy individuals that were indistinguishable from those of schizophrenic patients (but see also Krystal et al, 1999;Morgan et al, 2004). Schizophrenia-like saccadic disturbances were also observed in healthy subjects (Radant et al, 1998;Avila et al, 2002) and in monkeys (Condy et al, 2005) following ketamine treatment.…”