A two-arm parallel group randomized feasibility trial of a mobile application-delivered mindfulness exercise in distressed adults: Dropping anchor presented as an annotated image sequence

Mobile apps show promise for teaching mindfulness skills, but poor engagement limits their therapeutic impact. Most apps rely on audio-guided meditations, highlighting the need to explore novel delivery methods. This study evaluated the feasibility of delivering the dropping anchor mindfulness exercise as an annotated image sequence via the ACTaide prototype app. This 4-week, parallel two-arm randomized feasibility trial was conducted virtually from October to December 2024. Distressed Canadian adults were recruited through Prolific. Participants were randomized (blinded) using a computer-generated allocation sequence to the ACTaide prototype (annotated image sequence plus reminders) or a control app (reminders only). Both conditions included a 1-hour workshop introducing the exercise and two weeks of practice using their assigned app. Primary feasibility outcomes include app acceptability, adherence, and retention. Over one month, 296 Prolific members completed screening and 82 were eligible. Of these, 77 were randomized and N = 62 received the intervention (intervention n = 30; control n = 32). Acceptability: 85.71% (95% CI [0.69, 0.94]) of intervention participants rated the ACTaide prototype as sufficiently acceptable. Participants described the image sequence as a helpful tool for focus and memory. Adherence: Despite technical issues with reminders, 73.33% (95% CI: [0.56, 0.86]) of intervention and 81.25% (95% CI: [0.65, 0.91]) of control participants practiced at least once daily on average. Retention: Among participants who received the intervention, 96.77% (95% CI: [89%, 99%]) completed the follow-up. Overall, progression criteria were met and no adverse events occurred. The ACTaide prototype demonstrated feasibility, with participants highlighting the image sequence as an effective tool for learning, remembering, and practicing the mindfulness exercise. Findings support advancement to future trials and provide guidance for assessing efficacy. • Novel visual approach for mobile mindfulness exercise showed high feasibility • Users described image sequence as a helpful aid for memory and focus • Intervention achieved high acceptability, promising adherence, and exceptional retention • First study to investigate dropping anchor as standalone mindfulness intervention