Objective: Mindfulness training can relieve posttraumatic stress disorder (PTSD) symptoms in military veterans and others but is inconsistently accessible. Self-guided mobile apps could improve access but their acceptability, feasibility, and benefits for veterans with PTSD have not been established. We conducted a pilot randomized trial of Mindfulness Coach (MC), a free, publicly available, trauma-informed mobile app tailored to veterans.

Method: U.S. veterans with PTSD (n = 173) were randomized to self-guided use of MC or waitlist control (WLC) with 8-week follow-up. Clinical outcomes were PTSD symptoms (PTSD Symptom Checklist-5), depression symptoms (Patient Health Questionnaire, nine item), and psychosocial functioning (Brief Inventory of Psychosocial Functioning). Primary analyses were intent-to-treat using linear mixed models with maximum likelihood estimation. App uptake, objective usage, and usability ratings measured acceptance and feasibility.

Results: Participants varied in age, gender, and ethnoracial identity; most reported recent mental health care utilization. Although study attrition was high (68.4% overall) due to participant dropout (treatment: 43.0%; control: 43.7%) and technical study issues (23% overall), diagnostic tests showed no evidence of bias due to missingness. Study completers (MC: n = 19; WLC: n = 37) showed medium effects on PTSD symptoms (b = -9.31, d = -0.69) and depression (b = -3.10, d = -0.52). Higher-intensity users showed greater benefits. App engagement trended lower for women and minoritized subpopulations. No changes were observed in psychosocial functioning. Usability and helpfulness ratings were favorable.

Conclusions: Transdiagnostic clinical benefits indicate promise for MC as a public health resource for veterans with PTSD. Further study is warranted to confirm these benefits and ensure consistent engagement across subpopulations. (PsycInfo Database Record (c) 2024 APA, all rights reserved).