A theory-driven mobile application based on iterative collaborative design principles to support depression self-management in older adults: development and usability evaluation of “Mind Garden”

Older adults with late-life depression can experience substantial barriers to self-management. Mobile health applications may provide accessible support, but few applications have been developed specifically around the needs of this heterogeneous population. This study aimed to describe the theory-informed, iterative development of “Mind Garden,” a mobile application designed to support depression self-management among adults aged 60 years and older, and to conduct a descriptive usability evaluation. The Behavior Change Wheel (BCW) served as the overarching intervention-development framework. Its Capability–Opportunity–Motivation–Behaviour (COM-B) model was used for behavioral diagnosis, the Theoretical Domains Framework (TDF) supported determinant mapping, the Behaviour Change Technique Taxonomy version 1 (BCTTv1) specified intervention content, and the APEASE (affordability, practicability, effectiveness and cost-effectiveness, acceptability, side-effects and safety, and equity) criteria supported selection decisions. Development comprised three iterative phases: understanding the problem and user needs; translating findings into application features; and evaluating and refining the prototype. Evidence synthesis, focus groups with older adults and a multidisciplinary expert group, a 10-day prototype trial, qualitative content analysis, and perceived usability was assessed using the Chinese version of the mHealth App Usability Questionnaire (MAUQ), with responses ranging from 1 (“extremely strongly agree”) to 7 (“extremely strongly disagree”); lower mean scores indicate more favorable perceived usability. The behavioral diagnosis identified capability-, opportunity-, and motivation-related barriers and facilitators, together with motivational, educational, supportive, technology-adaptation, and safety needs. Seven intervention functions and 22 behavior change techniques were translated into nine application modules. Following the 10-day trial, participants described the prototype as useful and generally easy to use and suggested refinements to eight modules. Among 14 participants, the mean MAUQ total score was 3.08 (SD = 0.55). This formative development study shows how the BCW and related specification tools can be used to translate evidence, stakeholder input, and behavioral determinants into a mobile application for older adults with late-life depression. The study provides qualitative and descriptive usability findings from a prototype evaluation, but it does not establish clinical effectiveness; larger and longer studies are required.