NCT05907369

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

Status unknown NA Last updated 28 February 2024

What this trial tests

NA trial testing Active EC training in Obsessive-Compulsive Disorder in 55 participants. Status unknown.

Timeline

20 January 2023

Primary endpoint
30 December 2023

29 March 2024

Quick facts

Lead sponsor	Ferdowsi University of Mashhad
Phase	NA
Status	Status unknown
Study type	INTERVENTIONAL
Allocation	randomized
Design	factorial
Masking	single
Primary purpose	treatment
Enrollment	55
Start date	20 January 2023
Primary completion	30 December 2023
Estimated completion	29 March 2024
Sites	1 location across Iran

Drugs / interventions tested

• Active EC training
• Sham EC training
• Active tDCS
• Sham tDCS

Conditions studied

• Obsessive-Compulsive Disorder — all drugs for Obsessive-Compulsive Disorder →

Sponsor

Ferdowsi University of Mashhad

Who can join

Adults 18 to 55, any sex, with Obsessive-Compulsive Disorder. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

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.

Publications & conference data

3 peer-reviewed publications reference this trial (live from Europe PMC):

1. Disgust-reduction evaluative conditioning (DREC) and brain stimulation in patients with contamination-based obsessive-compulsive disorder: a protocol for a randomized control trial.
   Al Mohaddesin FR, Moghimi A, Moghimi A, Fadardi JS. · · 2023 · cited 3× · PMID 38001473 · DOI 10.1186/s13063-023-07791-2
2. Disgust-reduction evaluative conditioning (DREC) and tDCS in contamination-based OCD: a randomized controlled trial.
   Raeis Al Mohaddesin F, Moghimi A, Kobravi H, Yaghoubian E, et al · · 2026 · PMID 41942946 · DOI 10.1186/s12888-026-07934-0
3. Disgust-Reduction Evaluative Conditioning (DREC) and tDCS in Contamination-Based OCD: A Randomized Controlled Trial
   Mohaddesin FRA, Moghimi A, Kobravi H, Yaghoubian E, et al · · 2025 · DOI 10.1101/2025.06.04.25328293