Cognitive Conditioned Pain Modulation (CognitiveCPM)

Conditioned Pain Modulation With Ultra-Brief Conditioning Stimulus

This "pain reduces pain" study looks at how the brain reduces pain when a person feels two painful sensations at the same time. There is considerable evidence that the brain can "turn down" pain using natural endogenous pain-control systems. The current CPM study measures whether attentional processes can also make a measurable contribution to pain inhibition alongside neurochemical mechanisms.

Study Overview

• Status: Completed
• Conditions: Healthy Participants
• Intervention / Treatment: Behavioral: test stimulus; Behavioral: conditioned pain modulation

Detailed Description

Conditioned pain modulation (CPM) is a natural process where feeling pain in one part of the body (e.g., a conditioning stimulus to the wrist) can reduce pain felt in another part of the body (a test stimulus to the foot). There is considerable evidence from both animal and human studies that the painful conditioning stimulus can stimulate the brain to activate neurochemical pain-control pathways (e.g., endogenous opioids), which are believed to take 30-120 seconds to fully engage. The current CPM study measures whether attentional processes can also make a measurable contribution to pain inhibition alongside neurochemical mechanisms.

Primary measures: Graphic ratings scale "worst pain" ratings.

The primary measure of the current study graphic ratings scales (worst pain ratings) will measure how much pain participants feel on their foot during foot only (test stimulus), vs. how much pain participants feel on their foot (test stimulus during simultaneous foot (test stimulus) + wrist (conditioning stimulus).

The current investigators predict that pain (e.g., the conditioning stimulus) naturally demands attention and can pull attention away from the original pain source (the test stimulus), resulting in CPM-like reductions in pain of the test stimulus.

Secondary measure #1. Cognitive measures are introduced in the current study, to quantify how much (if at all) the conditioning stimulus reduces pain of the target stimulus via attentional mechanisms. Participants estimate what percentage of their attention was directed to their foot (the test stimulus) during foot only vs. during foot + wrist (test + conditioning stimulus). This will measure whether the conditiioning stimulus to the wrist reduces how much attention participants focus on their foot. Analyses will also measure whether the amount of attention shift away from the foot (via participants; subjective ratings) is correlated with CPM robustness (reduction in pain of foot during duel stimulation).

Secondary measure #2. As another secondary measure of attention during one vs. two simultaneous pain stimuli, this study involves a divided attention auditory listening task that becomes harder when pain demands more attention (Craik et al., odd number divided attention task during single test pain stimuli vs. simultaneous test + conditioning stimuli). The more errors the participant makes on the divided attention task, the more attention diverted away from the auditory task by pain. Analyses will measure whether the number of errors on the divided attention task is correlated with CPM robustness (reduction in pain of foot, during duel thermal stimulation).

Exploratory measures. As exploratory measures, participants will rate how distracted they were and how difficult it was to concentrate (on 0-10 rating scales during test stimulus alone verses test + conditioning noxious thermal heat stimuli).

In summary, embedding these cognitive measures into the CPM protocol may enhance mechanistic interpretation accuracy by quantifying attentional contributions to pain inhibition in specific CPM protocols, thereby complementing existing approaches to pain phenotyping and reducing unexplained variance in CPM outcomes.

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Washington
    • Seattle, Washington, United States, 98195
      • University of Washington Seattle

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion criteria:

• Only University of Washington students in eligible psychological courses are
• eligible. General public is not eligible.
• Enrolled psychology students fluent in English,
• Age ≥18 y, able to follow instructions.

Exclusion criteria:

• Seizure history,
• Migraines,
• Diabetes,
• Extreme pain insensitivity,
• Motion sickness,
• or prior participation in this protocol.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Single pain stimulus; test pain stimulus alone	Behavioral: test stimulus; single brief stimulus to foot only
Experimental: dual pain stimuli; simultaneous foot (test stimulus + wrist (conditioning stimulus)	Behavioral: conditioned pain modulation; simultaneous stimuli to foot (test stimulus) and wrist (conditioning stimulus)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
worst pain ratings of foot only	graphic rating scale from 0 (no pain) to 10 (excruciating pain)	rated immediately after each thermal stimulus
worst pain on graphic rating scale during test+conditioning stimulus	graphic rating scale from 0 (no pain) to 10 (excruciating pain)	measured immediately after the stimuli

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
% of attention devoted to foot during test stimulus only (0-100% scale)	verbal ratings where higher numbers = more attention	rated immediately after the stimuli
% of attention devoted to foot during test+conditioning stimuli (0-100% scale)	verbal ratings where higher numbers = more attention	rated immediately after the thermal stimuli
Divided attention during test stimulus only (% correct, where 100% is highest accuracy)	Accuracy monitoring a string of auditory numbers, the odd number task during test stimulus	Day 1, during the thermal stimulus
Divided attention during test stimulus + conditioning stimulus (% correct, 100% is highest )	Accuracy monitoring a string of auditory numbers, the odd number task during dual stimuli	Day 1, during the thermal stimuli

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
distraction difficulty during test stimulus only (0 to 10 scale, where 10 is most distracting)	Exploratory: Distraction during the single test stimulus (graphic rating scales)	immediately after the phase 1 thermal stimuli
distraction difficult during simultaneous test + conditioning stimuli (graphic rating scale)	Exploratory: 0-10 distraction during simultaneous test + conditioning stimulus (10 =highest distraction)	Exploratory: immediately after the phase 1 thermal stimuli
difficulty concentrating during test stimulus only (0 to 10 scale, 10 = most difficult concentr	Exploratory: difficulty concentrating during the single test stimulus (graphic scales)	Exploratory: immediately after the phase 1 thermal stimuli
difficulty concentrating during simultaneous test + conditioning stimuli (graphic rating scale)	Exploratory: difficulty concentrating during simultaneous test + conditioning stimulus, 10 = most difficult	Exploratory: immediately after the phase 1 thermal stimuli

Collaborators and Investigators

• Sponsor: University of Washington
• Collaborators: Mayday Fund
• Investigators: Principal Investigator: Hunter Hoffman, University of Washington

Publications and helpful links

General Publications

• Yarnitsky D. Conditioned pain modulation (the diffuse noxious inhibitory control-like effect): its relevance for acute and chronic pain states. Curr Opin Anaesthesiol. 2010 Oct;23(5):611-5. doi: 10.1097/ACO.0b013e32833c348b.

Study record dates

Study Major Dates

• Study Start (Actual): August 9, 2024
• Primary Completion (Actual): May 29, 2025
• Study Completion (Actual): May 29, 2025

Study Registration Dates

• First Submitted: November 14, 2025
• First Submitted That Met QC Criteria: November 14, 2025
• First Posted (Estimated): November 18, 2025

Study Record Updates

• Last Update Posted (Actual): January 7, 2026
• Last Update Submitted That Met QC Criteria: January 2, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Conditioned Pain Modulation
• Other Study ID Numbers: CPM2025

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Summary statistics will be made available to researchers upon reasonable request (e.g, for meta-analyses, etc). No individually identifiable information will be made available.
• IPD Sharing Time Frame: The de-identified summary data will be available from time of publication for at least five years after publication.
• IPD Sharing Access Criteria: The de-identified summary data will be e-mailed to researchers upon reasonable request

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No