Effects of tDCS on Cognitive Flexibility and EEG Oscillations in Orthorexia Nervosa

NCT07141979 | Recruiting

• 1 other identifier: E-10840098-202.3.02-35.59
• Study Type: interventional
• Target: 48
• Locations: 1 country
• Sites: 1

Brief Summary

Orthorexia Nervosa (ON); is a condition characterized by individuals being overly focused on healthy eating habits, constantly checking and classifying the foods they will consume. ON has not yet been clinically defined as an eating disorder or in a different category, and has not been included in DSM-5. Cognitive flexibility can be defined as a person's ability to quickly change their thinking and behaviors to adapt to different situations and changing conditions. It has been reported that cognitive flexibility skills are impaired in ON. There is evidence that tDCS, a neuromodulation method, increases cognitive flexibility skills. On the other hand, although there are EEG studies on eating disorders, there is no EEG study directly studying ON, and there is no information on the EEG profiles of individuals with high ON scores. For this reason, EEG studies on eating disorders and obsessive behaviors are generally generalized to orthorexia nervosa and are interpreted. This study aims to compare the EEG oscillations and cognitive flexibility skills of individuals with high ON scores with a control group and to examine the effects of anodal tDCS application on these two variables. For this purpose, a total of 48 individuals, 24 healthy and 24 high ON scores, will be included in the study. Participants will be randomly assigned to tDCS experimental and control groups. Therefore, 48 participants will be divided into 4 different subgroups of 12 people each. Data collection tools will be Informed Consent Form, Demographic Information Form, Beck Depression Inventory, Orthorexia Nervosa Test (TON-17), Cognitive flexibility task. First, participants will be subjected to a cognitive flexibility task by taking simultaneous EEG recordings, then tDCS stimulation will be initiated (active or sham) and after stimulation, a cognitive flexibility task will be performed by taking simultaneous EEG recordings again. EEG analyses will be performed using the Brain-Vision Analyzer program. Repeated Measures Analysis of Variance (within-group and between-groups) will be used in statistical analyses.

Conditions

Orthorexia Nervosa

Keywords

Orthorexia Nervosa; cognitive flexibility; tDCS; EEG Oscillations

Outcome Measures

Primary Outcomes (2)

• Change in EEG Oscillations in individuals with Orthorexia Nervosa for active vs. sham stimulation

  The EEG oscillations recording the event brain oscillations during the cognitive flexibility task from pre and post measurements. There are the five frequencies band which are Delta (0.5-3,5 Hz), Theta (4-7 Hz), Alpha (8-13 Hz), Beta (15-30 Hz) and Gamma (30-100 Hz). Data will be record simultaneously and analyzed. The analysis will be done with the BrainVisionAnalyzer program and power analysis will be made in Delta, Theta, Alpha, Beta, Gamma bands and the averages will be compared. Oscillations will be evaluated in terms of averages changing as an indicator of the effect of the neuromodulation preceding it.

  Baseline, 5 minutes after completion of the active/sham stimulation

• Change in Cognitive Flexibility Task score in individuals with Orthorexia Nervosa for active vs. sham stimulation

  A structured task-switching paradigm will be used to measure cognitive flexibility skills from pre and post test score in individuals with Orthorexia Nervosa \* The paradigm consists of two conditions: trials with a task switch and trials without a task switch. The experiment will include two blocks, with a total of 320 trials. Each block will contain 160 phases, consisting of 80 trials with a task switch and 80 trials without a task switch. Score averages will compare between pre and post test. Data will be record Excel by Psychopy program simultaneously. Performance will be evaluated for accuracy as an indicator of the effect of the neuromodulation preceding it.

  Baseline, 20 minutes after completion of the active/sham stimulation

Study Arms (2)

Experimental group

ACTIVE COMPARATOR

Participants will take active tDCS stimulation

Device: Active tDCS

Control group

SHAM COMPARATOR

Participants will take sham tDCS stimulation

Device: Sham tDCS

Interventions

Active tDCS DEVICE

20 min, 2 milliampere (mA), Anodal tDCS in left DLPFC

Experimental group

Sham tDCS DEVICE

20 min, left DLPFC Sham tDCS

Control group

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Being between the ages of 18-40,
• Having a score of 17 or less on the Beck Depression Inventory
• Having a score of 61 or more on the Test for Orthorexia Nervosa (TON-17) for the orthorexia group

You may not qualify if:

• Having a history of serious neurological and psychiatric illness,
• Currently taking medication that alters the cortical excitability level,
• Having visual defects that cannot be corrected with glasses
• Use of intracranial metal objects, implanted stimulating devices or pacemakers

Sponsors & Collaborators

• Istanbul Medipol University Hospital: lead

Study Sites (1)

Istanbul Medipol University

Istanbul, Turkey (Türkiye)

RECRUITING

Related Publications (11)

• Emek Savas DD, Yerlikaya D, G Yener G, Oktem Tanor O. Validity, Reliability and Normative Data of the Stroop Test Capa Version. Turk Psikiyatri Derg. 2020 Spring;31(1):9-21. doi: 10.5080/u23549. English, Turkish.

  PMID: 32594475 RESULT

• Du M, Peng Y, Li Y, Zhu Y, Yang S, Li J, Zou F, Wang Y, Wu X, Zhang Y, Zhang M. Effect of trait anxiety on cognitive flexibility: Evidence from event-related potentials and resting-state EEG. Biol Psychol. 2022 Apr;170:108319. doi: 10.1016/j.biopsycho.2022.108319. Epub 2022 Mar 22.

  PMID: 35331781 RESULT

• Dong G, Wang Y, Chen X. Anodal occipital tDCS enhances spontaneous alpha activity. Neurosci Lett. 2020 Mar 16;721:134796. doi: 10.1016/j.neulet.2020.134796. Epub 2020 Jan 30.

  PMID: 32006627 RESULT

• Donaldson PH, Kirkovski M, Yang JS, Bekkali S, Enticott PG. High-definition tDCS to the right temporoparietal junction modulates slow-wave resting state power and coherence in healthy adults. J Neurophysiol. 2019 Oct 1;122(4):1735-1744. doi: 10.1152/jn.00338.2019. Epub 2019 Aug 28.

  PMID: 31461371 RESULT

• Darna M, Stolz C, Jauch HS, Strumpf H, Hopf JM, Seidenbecher CI, Schott BH, Richter A. Frontal theta oscillations and cognitive flexibility: Age-related modulations in EEG activity. Aging Brain. 2025 Jun 24;8:100142. doi: 10.1016/j.nbas.2025.100142. eCollection 2025.

  PMID: 40620518 RESULT

• Chrysikou EG, Hamilton RH, Coslett HB, Datta A, Bikson M, Thompson-Schill SL. Noninvasive transcranial direct current stimulation over the left prefrontal cortex facilitates cognitive flexibility in tool use. Cogn Neurosci. 2013;4(2):81-9. doi: 10.1080/17588928.2013.768221.

  PMID: 23894253 RESULT

• Cavinato M, Genna C, Formaggio E, Gregorio C, Storti SF, Manganotti P, Casanova E, Piperno R, Piccione F. Behavioural and electrophysiological effects of tDCS to prefrontal cortex in patients with disorders of consciousness. Clin Neurophysiol. 2019 Feb;130(2):231-238. doi: 10.1016/j.clinph.2018.10.018. Epub 2018 Nov 29.

  PMID: 30580246 RESULT

• Borwick C, Lal R, Lim LW, Stagg CJ, Aquili L. Dopamine depletion effects on cognitive flexibility as modulated by tDCS of the dlPFC. Brain Stimul. 2020 Jan-Feb;13(1):105-108. doi: 10.1016/j.brs.2019.08.016. Epub 2019 Aug 31.

  PMID: 31494070 RESULT

• Berchio C, Annen LC, Bouamoud Y, Micali N. Temporal dynamics of cognitive flexibility in adolescents with anorexia nervosa: A high-density EEG study. Eur J Neurosci. 2023 Mar;57(6):962-980. doi: 10.1111/ejn.15921. Epub 2023 Feb 7.

  PMID: 36683346 RESULT

• Alizadehgoradel J, Nejati V, Sadeghi Movahed F, Imani S, Taherifard M, Mosayebi-Samani M, Vicario CM, Nitsche MA, Salehinejad MA. Repeated stimulation of the dorsolateral-prefrontal cortex improves executive dysfunctions and craving in drug addiction: A randomized, double-blind, parallel-group study. Brain Stimul. 2020 May-Jun;13(3):582-593. doi: 10.1016/j.brs.2019.12.028. Epub 2020 Jan 3.

  PMID: 32289681 RESULT

• Aboulafia-Brakha T, Manuel AL, Ptak R. Prefrontal transcranial direct current stimulation facilitates affective flexibility. Neuropsychologia. 2016 Jun;86:13-8. doi: 10.1016/j.neuropsychologia.2016.03.030. Epub 2016 Mar 30.

  PMID: 27039163 RESULT

MeSH Terms

Conditions

Orthorexia Nervosa

Condition Hierarchy (Ancestors)

Feeding and Eating Disorders; Mental Disorders

Central Study Contacts

Saliha Şahintürk Şentürk, PhD

CONTACT

+90 531 566 03 22; salihasahinturk@gmail.com

Melek Özden, PhD

CONTACT

+90 5079771646; melekozden1@gmail.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Masking Details: Participants will not know that which group they will be in
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Prof. Dr., Principal Investigator

Model Details: It is an experimental, randomised controlled trial. The data will be collected with the convenience sampling method from volunteer healthy people and individuals with orthorexia nervosa. The matched-group design method will be used.

Study Record Dates

• First Submitted: August 18, 2025
• First Posted: August 26, 2025
• Study Start: November 1, 2025
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): July 1, 2027
• Last Updated: April 1, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)