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Placebo-mediated, Naloxone-sensitive suggestibility of short-term memory performance


Stern, J; Candia, V; Porchet, R I; Krummenacher, P; Folkers, G; Schedlowski, M; Ettlin, D A; Schönbächler, G (2011). Placebo-mediated, Naloxone-sensitive suggestibility of short-term memory performance. Neurobiology of Learning and Memory, 95(3):326-334.

Abstract

Physiological studies of placebo-mediated suggestion have been recently performed beyond their traditional clinical context of pain and analgesia. Various neurotransmitter systems and immunological modulators have been used in successful placebo suggestions, including Dopamine, Cholecystokinin and, most extensively, opioids. We adhered to an established conceptual framework of placebo research and used the μ-opioid-antagonist Naloxone to test the applicability of this framework within a cognitive domain (e.g. memory) in healthy volunteers. Healthy men (n=62, age 29, SD=9) were required to perform a task-battery, including standardized and custom-designed memory tasks, to test short-term recall and delayed recognition. Tasks were performed twice, before and after intravenous injection of either NaCl (0.9%) or Naloxone (both 0.15mg/kg), in a double-blind setting. While one group was given neutral information (S-), the other was told that it might receive a drug with suspected memory-boosting properties (S+). Objective and subjective indexes of memory performance and salivary cortisol (as a stress marker) were recorded during both runs and differences between groups were assessed. Short-term memory recall, but not delayed recognition, was objectively increased after placebo-mediated suggestion in the NaCl-group. Naloxone specifically blocked the suggestion effect without interfering with memory performance. These results were not affected when changes in salivary cortisol levels were considered. No reaction time changes, recorded to uncover unspecific attentional impairment, were seen. Placebo-mediated suggestion produced a training-independent, objective and Naloxone-sensitive increase in memory performance. These results indicate an opioid-mediated placebo effect within a circumscribed cognitive domain in healthy volunteers.

Physiological studies of placebo-mediated suggestion have been recently performed beyond their traditional clinical context of pain and analgesia. Various neurotransmitter systems and immunological modulators have been used in successful placebo suggestions, including Dopamine, Cholecystokinin and, most extensively, opioids. We adhered to an established conceptual framework of placebo research and used the μ-opioid-antagonist Naloxone to test the applicability of this framework within a cognitive domain (e.g. memory) in healthy volunteers. Healthy men (n=62, age 29, SD=9) were required to perform a task-battery, including standardized and custom-designed memory tasks, to test short-term recall and delayed recognition. Tasks were performed twice, before and after intravenous injection of either NaCl (0.9%) or Naloxone (both 0.15mg/kg), in a double-blind setting. While one group was given neutral information (S-), the other was told that it might receive a drug with suspected memory-boosting properties (S+). Objective and subjective indexes of memory performance and salivary cortisol (as a stress marker) were recorded during both runs and differences between groups were assessed. Short-term memory recall, but not delayed recognition, was objectively increased after placebo-mediated suggestion in the NaCl-group. Naloxone specifically blocked the suggestion effect without interfering with memory performance. These results were not affected when changes in salivary cortisol levels were considered. No reaction time changes, recorded to uncover unspecific attentional impairment, were seen. Placebo-mediated suggestion produced a training-independent, objective and Naloxone-sensitive increase in memory performance. These results indicate an opioid-mediated placebo effect within a circumscribed cognitive domain in healthy volunteers.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Dental Medicine > Clinic for Masticatory Disorders and Complete Dentures, Geriatric and Special Care Dentistry
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2011
Deposited On:06 Feb 2011 15:08
Last Modified:05 Apr 2016 14:41
Publisher:Elsevier
ISSN:1074-7427
Publisher DOI:10.1016/j.nlm.2011.01.005
PubMed ID:21277984
Permanent URL: http://doi.org/10.5167/uzh-44037

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