Tailored implementation of multidomain intervention to prevent cognitive impairment in community-dwelling older adults (Timi-Cog): A study protocol for a hybrid type 2 trial effectiveness-implementation study

Background & Objectives Despite growing recognition of multidomain non-pharmaceutical interventions (NPIs) for preventing cognitive impairment, their scalable implementation remains underdeveloped in China. This hybrid type 2 effectiveness-implementation study aims to bridge this gap by identifying implementation determinants, developing tailored strategies, and evaluating both implementation or health outcomes for multidomain NPIs and tailored strategies. Methods This protocol describes the design of an ongoing study. The formative phase has been completed: guided by Consolidated Framework for Implementation Research (CFIR), we integrated the COM-B model from the Behaviour Change Wheel (BCW) and the Theoretical Domains Framework (TDF) into an interview guide. Key informant interviews and focus groups identified barriers/facilitators, and the CFIR-ERIC matching tool finalized the implementation strategies. Subsequently, a hybrid type 2 cluster RCT will be conducted (or is currently underway) across 13 districts in Changxing County, Zhejiang. A total of 1170 older adults and 273 community health workers (CHWs) - including general practitioners, social workers, and volunteers - will be randomized into three study arms: Arm 1 will receive evidence-based practices (EBP) combined with intrinsic motivation; Arm 2, EBP with implementation strategies; and Arm 3 (control), health education with implementation strategies. The EBP package includes cardio-metabolic risk management, cognitive training, physical activity, and nutritional counseling. Implementation uses three bundles: (1) Capacity Building and Professional Support, (2) Collaborative Implementation and Network Building, and (3) an AI-enabled WeChat mini-program (Timi-Cog). Outcomes will be assessed using the Re -AIM framework over 18 months. Statistical analysis will employ mixed-effects linear models, adjusted for baseline characteristics and clustering effects. Conclusions & Implications This theory-informed initiative addresses the dementia prevention implementation gap in China. By combining BCW/TDF frameworks with implementation science methods and employing a hybrid design, the study will generate robust evidence on both clinical effectiveness and practical implementation, informing the integration of multidomain NPIs into China’s primary care system. Trial Registration Chinese Clinical Trial Registry (ChiCTR2500098587).