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NCT Number: NCT07141979

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

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.

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Key information

Conditions

Orthorexia Nervosa Feeding and Eating Disorders Mental Disorders

Age range

18 year–40 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Istanbul Medipol University

Istanbul, Turkey (Türkiye)

Location status: Recruiting

Location contact

Saliha Şahintürk Şentürk, PhD

CONTACT

[email protected]

+90 531 566 03 22

About this study

Measurement instruments:

Informed Voluntary Consent Form Demographic Information Form Edinburgh Hand Preference Survey Beck Depression Scale Test of Orthorexia Nervosa (TON-17) Cognitive Flexibility Task EEG and tDCS devices Statistics: Statistical analyses will be conducted using SPSS 25.0 (Statistical Package for Social Sciences) for Windows, and EEG data will be analyzed using the Brain-Vision Analyzer software.

Descriptive statistics for group variables such as age and education will be presented as means and standard deviations, while gender will be reported as frequency and percentage.

The normality of the distribution of variables will be assessed using the Kolmogorov-Smirnov test, and appropriate parametric or non-parametric tests will be applied based on the results.

To evaluate pre-test and post-test data for cognitive flexibility and EEG measures in the experimental and control groups, Repeated Measures Analysis of Variance (within- and between-subjects) or its non-parametric equivalent, the Friedman Test, will be used.

For all statistical tests, a significance level of p < 0.05 will be considered as the threshold for statistical significance.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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

Treatment and study plan

active tDCS

Device

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

Sham tDCS

Device

20 min, left DLPFC Sham tDCS

Primary outcomes

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

    Time frame: Baseline, 5 minutes after completion of the active/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.

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

    Time frame: Baseline, 20 minutes after completion of the active/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.

Study contacts

Contact information is provided by the study sponsor or research team.

Melek Özden, PhD

CONTACT

[email protected]

+90 5079771646

Saliha Şahintürk Şentürk, PhD

CONTACT

[email protected]

+90 531 566 03 22

Sponsors and collaborators

Lead sponsor

Istanbul Medipol University Hospital

Other

Registry information

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Aug 26, 2025
Registry last updated
Apr 1, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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