Real-Time EEG Neurofeedback Using a Subject-Independent Classifier in Women With Depressive Symptoms

NCT07815457 | Completed DMC

• 3 other identifiers: 1608250111211510CIN250068
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

This completed feasibility study examined whether right-handed women aged 18-35 years with mild-to-moderate depressive symptoms could use real-time electroencephalography (EEG) neurofeedback based on a subject-independent classifier to regulate brain activity toward a classifier-defined reference pattern. Participants were randomly assigned to receive either classifier-contingent visual feedback with performance-contingent monetary rewards or noncontingent sham visual feedback with yoked monetary rewards. All participants completed five training sessions over approximately 3 weeks. The primary purpose was to determine whether overall classifier accuracy during training exceeded the theoretical 50% chance level. Changes in clinician-rated and self-reported depressive symptoms, associations between classifier performance and symptom change, EEG spatial patterns, and procedural tolerability were exploratory.

Conditions

Depressive Sympotoms

Keywords

Brain-Computer Interface; Support Vector Machine; Brain Self-Regulation; Neuromodulation; EEG-Neurofeedback; neurofeedback

Outcome Measures

Primary Outcomes (1)

• Mean Overall Classifier Accuracy Across Five EEG Neurofeedback Sessions

  Classifier accuracy was the percentage of classifier outputs during regulation blocks that matched the instructed mental state. Each run contained 160 classifier outputs during regulation periods. Run-level accuracy was averaged across four runs to obtain a session-level value, and session-level accuracy was averaged across five sessions for each participant. Overall accuracy was compared with the theoretical 50% chance level within each arm and between arms.

  Across five training sessions over approximately 3 weeks

Other Outcomes (8)

• Mean Classifier Accuracy in Each EEG Neurofeedback Session

  Each of five training sessions over approximately 3 weeks

• Mean Classifier Accuracy During Early and Late Training

  Early training: Sessions 1-2; late training: Sessions 4-5, over approximately 3 weeks

• Change From Baseline in Hamilton Depression Rating Scale Score

  Baseline at 1-2 days before Session 1 to 1-2 days after Session 5; and baseline to 10-14 days after Session 5

Study Arms (2)

Contingent SIC-Based EEG Neurofeedback

EXPERIMENTAL

Participants completed five EEG neurofeedback sessions over approximately 3 weeks. During positive autobiographical memory recall and motor imagery blocks, a thermometer-like display was updated approximately once per second according to the real-time output of a pretrained subject-independent classifier. Participants received run-level classifier accuracy feedback and performance-contingent monetary rewards.

Behavioral: Contingent Subject-Independent Classifier-Based EEG Neurofeedback

Noncontingent Sham EEG Feedback

SHAM COMPARATOR

Participants completed the same five-session schedule, mental tasks, scripted instructions, and thermometer display. Display movements were randomly generated and independent of EEG activity and classifier output. Monetary rewards were yoked to the run-by-run reward sequence of the experimental-arm participant with the highest total reward, and participants were not informed that rewards were unrelated to their own classifier performance.

Behavioral: Noncontingent Sham EEG Feedback With Yoked Rewards

Interventions

Contingent Subject-Independent Classifier-Based EEG Neurofeedback BEHAVIORAL

Five sessions were delivered on separate days over approximately 3 weeks. Each session comprised four 300-second runs separated by 1-3-minute rest intervals. Each run contained four 20-second positive autobiographical memory recall blocks and four 20-second motor imagery blocks. A pretrained Filter Bank Common Spatial Pattern-linear support vector machine classifier processed 28 EEG channels in real time. The visual thermometer rose or fell by one level according to whether each classifier output matched the instructed mental state. At the end of each run, participants viewed classifier accuracy and received a prespecified performance-contingent monetary reward.

Contingent SIC-Based EEG Neurofeedback

Noncontingent Sham EEG Feedback With Yoked Rewards BEHAVIORAL

Participants received the same five-session schedule, task structure, visual display, and scripted instructions as the experimental arm. Each thermometer update was a randomly determined one-level increase or decrease and was independent of EEG activity. Rewards followed the run-by-run sequence obtained by the experimental-arm participant with the highest total reward and were not contingent on the control participant's classifier performance.

Noncontingent Sham EEG Feedback

Eligibility Criteria

• Age: 18 Years - 35 Years
• Gender Eligibility Details: Participants were required to self-identify as women and to report female sex assigned at birth during the intake interview.
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Self-identification as a woman.
• Female sex assigned at birth, reported during the intake interview
• Self-reported right-handedness
• Age 18-35 years
• Beck Depression Inventory-II score of 14-29
• Hamilton Depression Rating Scale score below 24
• Score below 2 on the suicide-related item of both the Beck Depression
• Inventory-II and Hamilton Depression Rating Scale

You may not qualify if:

• Current psychotherapy
• Self-reported history of bipolar disorder or schizophrenia
• Prior suicide attempt
• Self-reported history of post-traumatic stress disorder, obsessive-compulsive disorder, substance use disorder, or anorexia nervosa
• Neurological disorder, including dementia, brain tumor, or epilepsy
• Intellectual disability
• Regular or intermittent use of benzodiazepines, anticonvulsants, or psychostimulants
• Use of another psychotropic medication unless the medication and dose had remained unchanged for at least 3 months before enrollment

Sponsors & Collaborators

• Pontificia Universidad Catolica de Chile: lead

Study Sites (1)

Laboratory for Brain-Machine Interfaces and Neuromodulation, Pontificia Universidad Católica de Chile

Santiago, RM, 8320000, Chile

Location

Study Officials

• Sergio M Ruiz, MD, PhD

  Department of Psychiatry, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile

  PRINCIPAL INVESTIGATOR

• Ranganatha Sitaram, ME, PhD

  Department of Radiology, St. Jude Children's Research Hospital, Memphis (TN), USA.

  STUDY CHAIR

• Jaime A Pereira, MD, PhD

  Department of Psychiatry, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Participants and the trained clinical psychologists who administered the Hamilton Depression Rating Scale were masked to group allocation throughout the study. The personnel operating the neurofeedback system were not reported as masked.
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Two parallel arms with 1:1 randomized allocation. The experimental arm was implemented before the control arm only to generate the yoked reward schedule; the implementation order did not determine assignment.

Study Record Dates

• First Submitted: August 31, 2026
• First Posted: September 11, 2026
• Study Start: January 4, 2019
• Primary Completion: January 23, 2023
• Study Completion: January 30, 2023
• Last Updated: September 11, 2026

Record last verified: 2026-08

Locations

CL (1)