This randomized controlled trial investigates the neurophysiological, physiological, and attentional effects of Cognitive-Behavioral Therapy (CBT) in individuals with restrictive-type anorexia nervosa (AN). The study compares two groups: one receiving a 12-week CBT intervention, and one placed on a waitlist (no active treatment during the study period). All participants undergo pre- and post-intervention assessments using electroencephalography (EEG), galvanic skin response (GSR), and eye-tracking while exposed to visual stimuli related to food, body image, and self-appearance. The primary outcomes include neural changes in attention and emotional processing (P300, LPP, frontal alpha asymmetry), physiological arousal (skin conductance), and visual attention biases (fixation duration and gaze distribution). The aim is to determine whether CBT leads to measurable improvements in neurobiological and attentional mechanisms related to body image disturbance and food-related anxiety in AN, contributing to biomarker-informed psychotherapy approaches.
Anorexia nervosa (AN) is a severe psychiatric disorder characterized by distorted body image, food restriction, and intense fear of weight gain. Despite the effectiveness of Cognitive-Behavioral Therapy (CBT) in targeting maladaptive cognitions and behaviors, its underlying neurophysiological mechanisms remain insufficiently understood. This study aims to evaluate the effects of a 12-week CBT intervention on neural, physiological, and attentional responses in individuals with restrictive-type AN using a randomized controlled trial design. Sixty female participants (aged 18-35) with restrictive-type AN will be recruited and randomly assigned to one of two groups: a CBT intervention group (n = 30) and a waitlist control group (n = 30). Both groups will undergo baseline and post-intervention assessments using EEG, GSR, and eye-tracking. The CBT intervention will consist of weekly 60-minute sessions for 12 weeks, delivered by trained therapists, and will target body image distortion, cognitive restructuring, exposure to food-related stimuli, emotional regulation, and avoidance behaviors. During the experimental task, participants will view a series of visual stimuli including (1) self-images (unaltered, altered-thin, altered-overweight), (2) food images (low- vs. high-calorie), and (3) images of other female bodies (thin vs. normal weight). EEG markers of interest include P300 (attentional salience), Late Positive Potential (LPP; sustained emotional reactivity), and frontal alpha asymmetry (indicative of affect regulation and self-referential processing). It is hypothesized that CBT will lead to reductions in P300 and LPP amplitudes and an increase in left-frontal cortical activity, indicating enhanced emotional control and reduced fixation on thin-ideal stimuli. GSR will be used to assess physiological arousal in response to distressing stimuli. It is expected that post-CBT participants will exhibit lower skin conductance responses (SCRs) to body and food images, indicating improved autonomic regulation. Eye-tracking data will capture fixation durations and gaze patterns. Participants in the CBT group are expected to show less visual attention toward "problematic" body areas (waist, stomach, thighs) and reduced avoidance of high-calorie food images compared to the waitlist group. Participants will also complete standardized psychometric instruments including the Eating Disorder Examination Questionnaire (EDE-Q), Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory (BAI), the Yale-Brown Obsessive-Compulsive Scale for Body Dysmorphic Disorder (YBOCS-BDD), and the Cognitive Emotion Regulation Questionnaire (CERQ) at both time points. This trial will provide critical insights into the neurophysiological and attentional mechanisms of CBT in AN, aiming to identify objective biomarkers of therapeutic change. Results may inform precision-based treatment models and support the development of digitally enhanced or neuromodulation-augmented therapies for eating disorders.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
60
Manualized 12-week CBT protocol focused on reducing body image disturbance, distorted beliefs about food and appearance, and avoidance behaviors in individuals with anorexia nervosa. The intervention incorporates psychoeducation, cognitive restructuring, emotional regulation, food exposure, and body image work.
Üsküdar University Neuro Marketing Lab.
Istanbul, Turkey (Türkiye)
RECRUITINGChange in EEG P300 amplitude in response to body image stimuli
P300 amplitudes will be extracted from EEG data during visual exposure to body image stimuli. Reduced amplitudes post-CBT are hypothesized to indicate reduced attentional salience and hyperfocus on appearance-related cues. P300 amplitudes will be extracted from EEG data during visual exposure to body image stimuli. Reduced amplitudes post-CBT are hypothesized to indicate reduced attentional salience and hyperfocus on appearance-related cues.
Time frame: aseline and Week 12
Change in Late Positive Potential (LPP) amplitude to body and food stimuli
LPP amplitudes will be measured during viewing of thin, overweight, and food-related images. A reduction post-CBT suggests decreased sustained emotional reactivity to distressing visual input.
Time frame: Baseline and Week 12
Change in frontal alpha asymmetry during self-image viewing
Frontal alpha asymmetry (FAA), computed from EEG data, will be used to index emotional regulation. An increase in left-dominant FAA is expected post-CBT, reflecting enhanced emotional control and positive self-perception.
Time frame: Baseline and Week 12
Change in skin conductance response (SCR) to body and food stimuli
Skin conductance responses will be measured via GSR during visual exposure to self-body, other-body, and food stimuli. Decreased SCR amplitudes post-CBT will indicate reduced physiological arousal and distress.
Time frame: Baseline and Week 12
Change in fixation duration on weight-related body areas
Eye-tracking will assess gaze fixation duration on areas of interest (waist, thighs, stomach). Post-CBT reductions in fixation on these regions suggest reduced attentional bias toward body dissatisfaction zones.
Time frame: Baseline and Week 12 Baseline and Week 12
Change in Eating Disorder Examination Questionnaire (EDE-Q) scores
The EDE-Q assesses eating disorder symptoms across four subscales: Restraint, Eating Concern, Weight Concern, and Shape Concern. Each item is rated from 0 (no pathology) to 6 (high pathology). Global score ranges from 0 to 6. Higher scores indicate greater eating pathology. A reduction in post-treatment scores indicates improvement in eating disorder symptoms.
Time frame: Baseline and Week 12
Change in Beck Depression Inventory-II (BDI-II) scores
The BDI-II consists of 21 items scored from 0 to 3, yielding a total score between 0 and 63. Higher scores reflect more severe depressive symptoms: 0-13: minimal 14-19: mild 20-28: moderate 29-63: severe A decrease in BDI-II score post-CBT is expected, reflecting reduced depressive symptoms.
Time frame: Baseline and Week 12
Change in Beck Anxiety Inventory (BAI) scores
The BAI includes 21 items rated from 0 to 3, with a total score ranging from 0 to 63. Higher scores indicate more severe anxiety: 0-7: minimal 8-15: mild 16-25: moderate 26-63: severe Post-CBT reductions in BAI scores suggest improved anxiety regulation.
Time frame: Baseline and Week 12
Change in Yale-Brown Obsessive Compulsive Scale - Body Dysmorphic Disorder Version (YBOCS-BDD) scores
The YBOCS-BDD contains 12 items rated from 0 to 4, yielding a total score range of 0 to 48. Higher scores reflect greater severity of body image-related obsessions and compulsions. Scores ≥ 20 are considered moderate to severe. Post-treatment reductions reflect decreased symptom severity.
Time frame: Baseline and Week 12
Change in Cognitive Emotion Regulation Questionnaire (CERQ) scores
The CERQ includes 36 items rated from 1 (almost never) to 5 (almost always), across 9 subscales (e.g., catastrophizing, reappraisal, rumination). Subscale scores range from 4 to 20. Higher scores in adaptive subscales and lower scores in maladaptive subscales post-CBT indicate improved emotional coping. The CERQ includes 36 items rated from 1 (almost never) to 5 (almost always), across 9 subscales (e.g., catastrophizing, reappraisal, rumination). Subscale scores range from 4 to 20. Higher scores in adaptive subscales and lower scores in maladaptive subscales post-CBT indicate improved emotional coping.
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Time frame: Baseline and Week 12
Change in subjective distress ratings on Visual Analog Scale (VAS)
The VAS is a self-reported 0-10 scale used to assess momentary emotional distress following exposure to visual stimuli. 0 = no distress 10 = extreme distress Lower VAS scores after CBT indicate increased emotional tolerance of body and food-related images.
Time frame: Immediately after the experimental task at both baseline and Week 12