The Effect of the Safe and Sound Protocol on Depression and Anxiety Symptoms

Primary outcomes

1. PHQ-9

   Time frame: 10 minutes at enrollment visit and 10 minutes at final study visit 3 weeks after enrollment

   The 9-question Patient Health Questionnaire (PHQ-9) is a self-report screening tool for adults in primary care settings for assessing the presence and severity of depression symptoms. Items are aligned with the DSM-5 diagnostic criteria for MDD and queries the individual's experience in the past two weeks. Likert-type responses range from 0 ("Not at all") to 3 ("Nearly every day"). Good reliability and validity have been demonstrated. The PHQ-9 score is the key outcome variable for MDD symptoms.

   The total score is obtained by summing the values of the seven items. The total score ranges from 0 to 27, with higher scores indicating greater severity of depressive symptoms.

2. GAD-7

   Time frame: 10 minutes at enrollment visit and 10 minutes at final study visit 3 weeks after enrollment.

   The Generalized Anxiety Disorder 7 (GAD 7) is a self-administered measure of the frequency and severity of generalized anxiety disorder symptoms based on seven DSM-5 diagnostic criteria for GAD. It is typically used in outpatient and primary care settings. Response options are a Likert-type scale ranging from 0 ("Not at all") to 3 ("Nearly every day"). An additional question is a global rating of the severity of the patient's anxiety over the past 2 weeks. The measure is considered sensitive and has shown adequate internal consistency reliability and validity for assessing anxiety across a wide range of samples and settings. The GAD-7 score is the key outcome variable for GAD symptoms.

   The scoring involved summing the values of all seven items to obtain a score between 0 and 21. Higher scores indicate greater severity of anxiety symptoms.

3. BPQ-SF

   Time frame: 10 minutes at enrollment visit and 10 minutes at final study visit 3 weeks after enrollment.

   The Body Perception Questionnaire - Short Form (BPQ-SF) is an abbreviated version of the original self-report measure of body awareness and autonomic reactivity. The questionnaire consists of two subscales, Body Awareness (26 items) and Autonomic Nervous System Reactivity (20 items). The Likert-type scale answers range from 1 ("Never") to 5 ("Always"). Total scores for each subscale, which are key outcome variables, are summed and compared to T-scores in the BPQ Manual.

4. Heart Period and Respiratory Sinus Arrhythmia

   Time frame: 10 minutes at enrollment visit and 10 minutes at final study visit 3 weeks after enrollment.

   Heart period will be recorded at 1000 Hz using a Polar H10 chest strap device. This device has shown strong agreement and small bias compared to electrocardiogram (ECG) recordings. It has been chosen as it is minimally invasive and easy for participants to put on.

   RSA and heart period will be used to calculate the vagal contribution to regulation of the heart, i.e., vagal tone.