Disgust Reduction Through Evaluative Conditioning (DREC) and tDCS in Contamination-Based OCD

February 26, 2024 updated by: Ali Moghimi, Ferdowsi University of Mashhad

Disgust Reduction Through Evaluative Conditioning and tDCS in Patients With Contamination-Based OCD

Obsessive-compulsive disorder (OCD) is a debilitating health condition that is known by intrusive and unwanted thoughts and repetitive behavioral or mental acts. 2-3% of the population suffers from OCD in their lifetime. The most common OCD subtype is contamination. The Serotonin-selective reuptake inhibitors (SSRIs) and cognitive-behavioral therapy (CBT) based on exposure and response prevention (ERP) technique are the first-line treatments for OCD. The challenge is that nearly half do not respond to the first-line treatments or have residual symptoms after completion of treatments. However, the prevalence of the disorder, diversity of symptoms, inadequate response rate, and necessity of having long-lasting treatment effects make the treatments of OCD more challenging.

It seems that abnormal, more intense disgust experience has a prominent role in developing and maintaining OCD symptoms, particularly the contamination subtype. Evaluative conditioning (EC), defined as transferring the value of the US to the CS through pairing them, is the most common way of establishing disgust responses. The present study aims to develop an emotion-based intervention technique using EC targeting disgust emotion in contamination-based OCD (C-OCD). The hypothesis is that EC training may modify disgust experiences. Disgust may be the culprit, at least in part, of cognitive deficiencies in OCD. The other hypothesis is whether disgust reduction-focused EC may improve cognitive function, such as attention bias and inhibitory control.

The orbitofrontal cortex (OFC) is one of the brain areas engaged in disgust processing and is mostly hyperactive in OCD patients. Cathodal transcranial direct current stimulation (tDCS) over OFC is one of the helpful neuromodulation methods in treating OCD. We aim to see if this method may help to regulate disgust experiences in combination with EC. The participants may be referred by psychiatrists or psychotherapists or be self-referred due to online advertisements or paper flyers. They will be randomly assigned to one of for arms of the study for sham or active EC training along with sham or active tDCS, to which they are blind. The novelty of the present study is the application of EC training in the clinical OCD population in combination with a neuromodulation method.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Disgust as a primary emotion has evolved to protect our lives by driving dirt and disease avoidance behaviors and motivating for cleaning and hygienic behaviors. In recent years, many studies have focused on the role of disgust in psychiatric disorders such as anxiety disorders, eating disorders, body dysmorphic disorders, and phobias. Nowadays, we have robust evidence of the correlation between disgust and the etiology and treatment of OCD symptoms, particularly the contamination subtype. The principal explanation for the insufficient treatment effect of ERP is that disgust is resistant to extinction.

Since evaluative conditioning is one of the main sources of disgust feeling, the same process may effectively reduce disgust. The present trial will try to pair contamination-related pictures that are disgust-eliciting with positive, pleasant pictures in order to modify their disgust valence. We also will administer this EC training plus to OFC cathodal tDCS to see if the EC effect becomes more significant than EC alone.

Study Type

Interventional

Enrollment (Estimated)

55

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 Contact

Study Contact Backup

  • Name: Faezeh Raeisalmohaddesin, MsC
  • Phone Number: 0098 09151232724
  • Email: fh.raeesi@gmail.com

Study Locations

  • Iran, Islamic Republic of
    • Khorassan Razavi
      • Mashhad, Khorassan Razavi, Iran, Islamic Republic of, 91779 48974
        • Recruiting
        • Ferdowsi University of Mashhad
        • Contact:
        • Principal Investigator:
          • Faezeh Raeisolmohaddesin, MsC
        • Contact:

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

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • The Diagnostic criteria of OCD in the Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5-TR) with the symptoms of contamination subtype
  • Able to read, write and do computerized tasks
  • Stable medication for at least the last three months
  • Filling out the written consent

Exclusion Criteria:

  • Severe physical illness
  • Severe other mental disorders
  • Alcohol and drug dependence
  • A history of epilepsy or seizure
  • Have metal or electronic implants in the head or use a cardiac pacemaker
  • History of head trauma or neurological disorders
  • Women who are pregnant or may be pregnant
  • Unable to complete questionnaires, computerized tasks, or informed consent

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: Treatment
  • Allocation: Randomized
  • Interventional Model: Factorial Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: aEC/ stDCS
Participants in this group receive active EC training but sham tDCS.
Other: Active EC training
The active EC includes pairing contamination-related pictures (CSs) with pleasant pictures (USs). The EC training takes about 15 minutes and is administered for ten sessions (5 days a week) in 4 difficulty levels.
Other: Sham tDCS
For the sham tDCS, the cathode is placed over the left OFC and the anode over the right cerebellum, the same as active tDCS. The device is on for 20 minutes, but the current intensity is under the threshold of affecting cortical activity modulation. The participants receive the sham tDCS in 10 sessions (5 days a week).
Active Comparator: sEC/atDCS
Participants in this group receive active tDCS training but sham EC training.
Other: Sham EC training
The active EC includes pairing contamination-related pictures (CSs) with neutral pictures (USs). The EC training takes about 15 minutes and is administered for ten sessions (5 days a week) in 4 difficulty levels, the same as active EC training.
Other: Active tDCS
For the active tDCS, the cathode is placed over the left OFC and the anode over the right cerebellum. The brain stimulation is delivered with a 2mA current intensity for 20 minutes in 10 sessions (5 days a week).
Experimental: aEC/atDCS
Participants in this group receive both active EC training and active tDCS.
Other: Active EC training
The active EC includes pairing contamination-related pictures (CSs) with pleasant pictures (USs). The EC training takes about 15 minutes and is administered for ten sessions (5 days a week) in 4 difficulty levels.
Other: Active tDCS
For the active tDCS, the cathode is placed over the left OFC and the anode over the right cerebellum. The brain stimulation is delivered with a 2mA current intensity for 20 minutes in 10 sessions (5 days a week).
Sham Comparator: sEC/stDCS
Participants in this group receive the sham EC training and also sham tDCS.
Other: Sham tDCS
For the sham tDCS, the cathode is placed over the left OFC and the anode over the right cerebellum, the same as active tDCS. The device is on for 20 minutes, but the current intensity is under the threshold of affecting cortical activity modulation. The participants receive the sham tDCS in 10 sessions (5 days a week).
Other: Sham EC training
The active EC includes pairing contamination-related pictures (CSs) with neutral pictures (USs). The EC training takes about 15 minutes and is administered for ten sessions (5 days a week) in 4 difficulty levels, the same as active EC training.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Disgust Feeling
Time Frame: From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)
Effect of evaluative conditioning, cathodal tDCS over OFC, and both on changing disgust feeling intensity measured by disgust rating scale. The scale rates from 0 (not disgusting) to 10 (very disgusting). Lower scores show less disgust feeling.
From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)
Clinical Symptoms Severity of Contamination-Based OCD
Time Frame: From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)
Change in Clinical symptoms of contamination-based OCD after evaluative conditioning, cathodal tDCS over OFC, and both, measured by Yale-Brown Obsessive-Compulsive scale. It is scored on a 5-point rating. The lower scores show less symptom severity.
From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The power spectrum of brain waves based on quantitative electroencephalogram
Time Frame: From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)
Effect of evaluative conditioning, cathodal tDCS over OFC, and both on power spectrum of recorded brain waves.
From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)
Attentional bias
Time Frame: From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)
Change in attentional bias toward contamination stimuli, measured by Dot-prob test, comparing evaluative conditioning, cathodal tDCS over OFC, and both.
From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)
Inhibitory control
Time Frame: From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)
Change in inhibitory control, measured by go/nogo and stop-signal tests, comparing evaluative conditioning, cathodal tDCS over OFC, and both.
From pre- to post-assessment (2 weeks after baseline assessment) and from pre- to follow-up assessment (10 weeks after baseline assessment)

Collaborators and Investigators

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

Sponsor

Ferdowsi University of Mashhad

Investigators

  • Study Director: Ali Moghimi, PhD, Ferdowsi University of Mashhad

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 20, 2023

Primary Completion (Actual)

December 30, 2023

Study Completion (Estimated)

March 29, 2024

Study Registration Dates

First Submitted

May 15, 2023

First Submitted That Met QC Criteria

June 7, 2023

First Posted (Actual)

June 18, 2023

Study Record Updates

Last Update Posted (Estimated)

February 28, 2024

Last Update Submitted That Met QC Criteria

February 26, 2024

Last Verified

September 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 3/56765
  • 100/18979 (Other Identifier: Cognitive Sciences and Technologies Council of Iran)

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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