Table 2.

Guiding principles for ENHANCE (Tailored Intervention for Brain Health and Cognitive Enrichment for Cognitive Health) intervention development.

Sources and key findings	Design objective	Intervention features
From the literature, behavior change theory, and usability testing, BCTsa have been shown to improve behavior change outcomes	Integrate evidence-based BCTs in the app and coaching	Goal setting and action planning: joint goal setting with the coach SMARTb goals are achievable within 6 weeks Focus on 1 risk factor at a time Self-monitoring and feedback: activity logging with feedback from app and coach Social support: regular coach contact (meetings and messaging) and Family and friend involvement encouraged Knowledge and skills: clear and practical information Step-by-step brief rehearsing (eg, blood pressure monitoring and exercise demonstrations)
From literature, theory, usability testing, and PPIc: positive framing sustains behavior change	Use strengths-based and positive reinforcement	Encouragement and rewards Strength-based language Emphasis on short-term gains and long-term benefits Relatable success stories
From literature, PPI, and usability testing: overburden—whether from multiple simultaneous behavior changes or complex app design—undermines engagement and sustained behavior change	Minimize cognitive and digital burden	Single active risk-factor module at a time Sequential progression guided by participant priorities and the coach Module completion before starting next Simple language Clear and simple in-game instructions and feedback Icons and videos prioritized over text A ≤12-year reading level Clear navigation Coach support for basic app use Jargon and text-heavy information avoided
From usability testing: gamification features—including progress tracking, personal rewards, and familiar or classic games with adaptive difficulty—enhanced engagement; competitive scoring relative to others was not preferred	Use of gamification features and familiar or classic games	Unified visual theme Positive reinforcement (messages, stars, and virtual meadow) Classic cognitive games with adaptive difficulty, personal progress rewards only; no competitive leaderboards
From PPI discussions: early, visible improvements are motivating and self-reinforcing	Design for rapid and observable progress	Components with effects within 6 weeks Trackable metrics (eg, blood pressure and steps) Early positive feedback
From PPI discussions: keeping the intervention “in-house” reduces participant and coach burden	Minimize external navigation	Most activities are delivered within the app Clear signposting to essential in-person care (eg, general practitioner and smoking cessation)
From literature, PPI, and usability testing: participants valued personalization, choice, and flexibility, and had heterogeneous physical abilities, needs, and preferences	Promote autonomy and tailor to diverse capabilities	Participant choice of risk factor module order and goals Multiple activity options and difficulty and mobility levels per module (eg, exercise videos) Customizable app settings (eg, sound and volume) One-to-one coaching to address individual needs

^aBCT: behavior change technique.

^bSMART: Specific, Measurable, Achievable, Relevant, and Time-Bound.

^cPPI: patient and public involvement and engagement.