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

Last updated: February 26, 2024
Sponsor: Ferdowsi University of Mashhad
Overall Status: Active - Recruiting

Phase

N/A

Condition

Kleptomania

Panic Disorders

Mood Disorders

Treatment

Active tDCS

Sham tDCS

Sham EC training

Clinical Study ID

NCT05907369
3/56765
100/18979
  • Ages 18-55
  • All Genders

Study Summary

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.

Eligibility Criteria

Inclusion

Inclusion Criteria:

  • The Diagnostic criteria of OCD in the Diagnostic and Statistical Manual of MentalDisorders 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

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 Design

Total Participants: 55
Treatment Group(s): 4
Primary Treatment: Active tDCS
Phase:
Study Start date:
January 20, 2023
Estimated Completion Date:
March 29, 2024

Study 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.

Connect with a study center

  • Ferdowsi University of Mashhad

    Mashhad, Khorassan Razavi 91779 48974
    Iran, Islamic Republic of

    Active - Recruiting

Not the study for you?

Let us help you find the best match. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.