Primary care brief mindfulness training for veterans with psychological distress: Protocol for a hybrid type I effectiveness-implementation randomized controlled trial.

Psychological distress, encompassing PTSD, depression, and anxiety-is highly prevalent among Veterans receiving care in Veterans Health Administration (VHA) primary care settings, yet it frequently goes untreated or undertreated. Traditional psychotherapies and psychiatric medications are often misaligned with Veterans' preferences for self-reliance, low-stigma formats, and skill-based approaches. Primary Care Brief Mindfulness Training (PCBMT) was developed as a brief, transdiagnostic, group-based mindfulness intervention co-facilitated by licensed mental health providers and Veteran peer specialists in VHA primary care. Two preliminary randomized controlled trials (RCTs) demonstrated reductions in PTSD and depression severity relative to control conditions. An ongoing study extends this work through a Hybrid Type I effectiveness-implementation trial at three geographically and demographically diverse VHA sites (Phoenix, San Diego, St. Louis). Three hundred primary care patients with clinically significant psychological distress are being randomized 1:1 to PCBMT or Moving Forward (MF), a transdiagnostic problem-solving group that serves as an active comparison condition. The primary outcome is change in total psychological distress as measured by the Depression Anxiety and Stress Scale (DASS-21) from baseline to post-intervention (8 weeks). Secondary aims will test transdiagnostic mediators (mindfulness, emotion regulation, psychological flexibility, thought suppression) and explore social determinants of health (SDOH) as potential moderators of initiation, completion, and clinical benefit. A qualitative implementation aim, guided by the Consolidated Framework for Implementation Research (CFIR), will characterize barriers and facilitators to support future scale-up. This protocol describes participant selection criteria, intervention conditions, facilitator training, outcome measurement, and analytic strategy. Trial Registration:ClinicalTrials.gov Identifier: NCT-06162741.