Memory Priming in General Anesthesia

September 4, 2019 updated by: Eleonora Orena, Fondazione I.R.C.C.S. Istituto Neurologico Carlo Besta

Memory Priming for Abstract and Concrete Words in General BIS Guided Propofol vs. Sevoflurane Anesthesia

Memory priming under general anesthesia is a phenomenon of incredible interest in the study of consciousness and unconscious cognitive processing, and for clinical practice.

However results from anesthesiological literature are divergent and methodologies vary.

To overcome these limits, the present study aims at better defining the phenomenon of memory priming under general anesthesia, manipulating as experimental variables both the anesthetic drug used and the stimuli primed.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Some patients may develop serious psychological sequelae after surgical intervention under general anesthesia due to implicit memory formation of intraoperative events.

A number of studies in the field of anesthesiology have tried to better define the phenomenon of implicit memory in general anesthesia, with conflicting results. While some studies demonstrated the existence of unconscious memory formation also under adequate general anesthesia (BIS ranging 40-60), others state that implicit memory formation is possible only during light sedation, and that, therefore, traumatic disorders due to unconscious intraoperative memories are imputable to inadequate anesthesiological intraoperative management. The methodologies used by these studies, however, are very heterogeneous, and often inaccurate from a cognitive point of view. Data from cognitive neuroscience, in fact, demonstrate that different linguistic material, e.g. abstract and concrete words, are processed and retrieved via different networks in the brain. Then, since different anesthetics are known to target different areas of the brain, it is assumable that implicit memory formation is influenced both by the specific drug used and by the type of stimuli primed.

Therefore in this experiment, the investigators aim at testing implicit memory for different word category, abstract vs. concrete words, in patients undergoing either propofol or sevoflurane general anesthesia. Also, a very strict methodology was used both for the construction of the stimuli and the stimulation and testing procedure, in order to maximize the priming effect and exclude the risk of false positive results. The investigators hypothesize that, considering the existing data on propofol and sevoflurane effects on the brain, and the known neural correlates for abstract and concrete word processing, the priming effect would be different for abstract and concrete words between patients under propofol or sevoflurane anesthesia.

Study Type

Interventional

Enrollment (Actual)

102

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Italy
      • Milan, Italy, 20133
        • Fondazione IRCCS Istituto Neurologico Carlo Besta

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • patient undergoing general anesthesia for back surgery
  • American Society of Anesthesiology (ASA) physical status classification I or II
  • Italian native speaker
  • right handed (assessed with the Edinburgh Handedness Inventory)
  • not to suffer from memory deficits, hearing impairment or any other medical/psychiatric condition that could affect the memory performance or hearing

Exclusion Criteria:

  • to develop a postoperative cognitive dysfunction or delirium or any other medical complication that could prevent the memory testing or that could affect memory performance

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Propofol Abstract Priming
Patients undergoing propofol general anesthesia and stimulation with a list of abstract words
Behavioral: Abstract priming
Patients were primed with a list of abstract during their general anesthesia
Drug: Propofol
Propofol general anesthesia
Experimental: Propofol Concrete Priming
Patients undergoing propofol general anesthesia and stimulation with a list of concrete words
Drug: Propofol
Propofol general anesthesia
Behavioral: Concrete priming
Patients were primed with a list of concrete during their general anesthesia
Active Comparator: Propofol Controls
Patients undergoing propofol anesthesia without any intraoperative priming
Drug: Propofol
Propofol general anesthesia
Behavioral: Controls
Patients did not receive any specific stimulation with words during their general anesthesia
Experimental: Sevoflurane Abstract Priming
Patients undergoing sevoflurane general anesthesia and stimulation with a list of abstract words
Behavioral: Abstract priming
Patients were primed with a list of abstract during their general anesthesia
Drug: Sevoflurane
Sevoflurane general anesthesia
Experimental: Sevoflurane Concrete Priming
Patients undergoing sevoflurane general anesthesia and stimulation with a list of concrete words
Behavioral: Concrete priming
Patients were primed with a list of concrete during their general anesthesia
Drug: Sevoflurane
Sevoflurane general anesthesia
Active Comparator: Sevoflurane Controls
Patients undergoing sevoflurane general anesthesia without any intraoperative priming
Behavioral: Controls
Patients did not receive any specific stimulation with words during their general anesthesia
Drug: Sevoflurane
Sevoflurane general anesthesia

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Implicit score
Time Frame: 24 hours
Implicit memory is tested through a word stem completion test, in which the participant has to complete a three-letter stem with the first word that comes to mind. The completion test comprises both target stems (stems of word primed intra-operatively) and foils. The number of correct completions of target stems and foils is recorded as target and non target hits. The implicit score is then calculated as (target hits - nontarget hits)/total target stimuli. The score can therefore range (absolute values) from -1 to +1, where a positive score indicates memory priming.
24 hours

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Explicit recall of intraoperative words
Time Frame: before discharge from the Recovery Room and at 24 hours
The number of intraoperative primed words that the patient is able to recall without any cue
before discharge from the Recovery Room and at 24 hours
Explicit recall of intraoperative events
Time Frame: before discharge from the Recovery Room and at 24 hours
The explicit recall of intraoperative events assessed with the Brice Interview
before discharge from the Recovery Room and at 24 hours
Target hits
Time Frame: 24 hours
The number of correct stem completions (hits) with target words (i.e. words heard intraoperatively)
24 hours
Nontarget hits
Time Frame: 24 hours
The number of correct stem completions (hits) with nontarget words (i.e. words not heard intraoperatively)
24 hours

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Fondazione I.R.C.C.S. Istituto Neurologico Carlo Besta

Collaborators

University of Milano Bicocca

Investigators

  • Principal Investigator: Eleonora F Orena, PhD, Fondazione IRCCS Istituto Neurologico Carlo Besta

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 7, 2013

Primary Completion (Actual)

September 15, 2016

Study Completion (Actual)

September 15, 2016

Study Registration Dates

First Submitted

October 30, 2018

First Submitted That Met QC Criteria

October 30, 2018

First Posted (Actual)

November 1, 2018

Study Record Updates

Last Update Posted (Actual)

September 6, 2019

Last Update Submitted That Met QC Criteria

September 4, 2019

Last Verified

September 1, 2019

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • AR-INNCB-PRIMING-2012

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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