Biofeedback Digital para Veteranos de Combate Diagnosticados com TEPT

The intervention is an 8-week hybrid program designed to reduce symptoms of PTSD and improve mental health. The program includes weekly online sessions (via Zoom) with a specialist psychologist experienced in biofeedback and trauma therapy. These sessions guide participants through the program, provide education on trauma and autonomic system and explain the biofeedback exercises. In addition to the weekly group sessions, participants engage in a dailyself-practice delivered through the NeuroBrave Sense mobile application, utilizing the provided wearable device ( Garmin watch) for real time biofeedback practices. Supplementary mental practice assignments are also delivered to participants via WhatsApp.

Participants in this arm will initially serve as a no-intervention control group for a period of 8 weeks, during which they will continue with their Treatment as Usual (TAU). Following this 8-week period, they will receive the full 'Mental Gym®' intervention, identical to the experimental group, including the mobile application, and weekly sessions.

The primary outcome is the change in the total score of the Posttraumatic Stress Disorder Checklist for DSM-5 (PCL-5). The PCL-5 is a 20-item self-report measure; items are rated on a 0-4 point scale. Total score ranges from 0 to 80, where higher scores indicate greater symptom severity. PCL scores are expected to reduce in the intervention but not in the control groups.

To assess long term improvement trajectories and retention, we will combine all intervention arm participants and conduct longitudinal within subjects analysis on primary and secondary change measures at post intervention, as well as 1.5-month Follow-up (Week 14), and 3-month Follow-up (Week 20). This analysis will also be used to identify subpopulations within our sample for whom the treatment was more or less beneficial.

We expect the clinical improvement to remain significant through the follow up time points.

change in resting heart rate variability (HRV) will be used as a physiological marker of autonomic regulation. HRV will be derived from inter-beat interval data collected during 5 min resting conditions during the first and the last group sessions using a wearable device and summarised using standard time-domain metrics (e.g., RMSSD). Higher HRV values and lower heart rate (HR) reflect greater parasympathetic activity and improved autonomic regulation. Resting HRV scores are expected to increase and resting HR to decrease in the intervention but not in the control groups.

Generalized anxiety symptoms will be assessed using the Generalized Anxiety Disorder 7-item questionnaire (GAD-7), a validated self-report measure of anxiety severity. Total scores range from 0 to 21, with higher scores indicating greater anxiety symptoms. Generalized anxiety symptoms are expected to reduce in the intervention but not in the control groups.

Depressive symptoms will be measured using the Patient Health Questionnaire-9 (PHQ-9), a validated self-report instrument assessing the severity of depressive symptoms over the past two weeks. Total scores range from 0 to 27, with higher scores indicating greater depressive symptom severity. Depressive symptoms are expected to reduce in the intervention but not in the control groups

Psychological resilience will be assessed using the 10-item Connor-Davidson Resilience Scale (CD-RISC-10), a validated self-report measure of perceived resilience and stress coping capacity. Total scores range from 0 to 40, with higher scores indicating greater resilience.Psychological resilience is expected to reduce in the intervention but not in the control groups.

Sleep quality will be measured using the Insomnia Severity Index (ISI), a validated self-report questionnaire assessing subjective sleep quality. The total SQS score will be used, with higher scores indicating poorer sleep quality. Sleep quality is expected to reduce in the intervention but not in the control groups.

The PTSD Checklist - 6-item version (PCL-6) is a validated self-report screening tool for Post-Traumatic Stress Disorder. It assesses symptoms such as intrusive thoughts, avoidance, and hyperarousal. Total scores range from 6 to 30, with higher scores indicate greater symptom severity. A decrease in scores over time represents clinical improvement.

The Outcome Rating Scale (ORS) is a 4-item visual analogue scale designed to measure change in three areas of client functioning: individual (personal well-being), interpersonal (family/close relationships), and social (work/school/friendships), as well as overall well-being. Total scores range from 0 to 40, with higher scores indicate better psychological wellbeing and functioning. An increase in scores over time represents improvement.