Psychological and Lifestyle Factors That Predict Adherence of Multi-domain Interventions for Promoting Brain Health

ToBrainHealth Intervention Trial - Three-arm personalised lifestyle optimisation study The ToBrainHealth intervention trial is an 8-week, three-arm controlled study designed to evaluate the impact of personalised, technology-supported strategies on adherence to healthy lifestyle recommendations in community-dwelling adults. The study is embedded in the Barcelona Brain Health Initiative (BBHI), a large longitudinal cohort that investigates determinants of brain health across ageing. The trial addresses a crucial challenge in brain-health promotion: despite strong evidence that modifiable lifestyle factors positively influence resilience and reduce the risk of cognitive decline, long-term adherence to lifestyle interventions remains low. Background and Rationale Ageing is associated with increasing prevalence of neurological disorders, particularly dementia, which represent the leading cause of disability globally. Cognitive decline is not inevitable; \~20% of older adults maintain youthful cognitive performance, reflecting brain resilience processes. Research from the BBHI cohort (\>6,000 adults aged 40-75 years) demonstrates that lifestyle quality, psychological wellbeing, sleep, social engagement and physical activity predict brain health trajectories. However, substantial variability exists between individuals. To better understand this variability, latent profile analysis of lifestyle and psychosocial data from the BBHI cohort identified three behavioural-psychological profiles: High Risk, Moderate Risk and Low Risk. High- and Moderate-Risk individuals exhibit poorer habits and lower levels of protective traits such as sense of coherence, self-reflection or emotional wellbeing, all of which influence adherence. These profiles provide an empirical basis for targeted interventions. Lifestyle interventions often fail due to barriers such as lack of personalisation, limited feedback, insufficient motivational support, technical difficulties, and fluctuating emotional states. Evidence shows that technology-supported programmes can enhance adherence when they provide clear guidance, personalised content, adaptive strategies, monitoring features, and-when appropriate-professional supervision. The ToBrainHealth digital solution operationalises this knowledge to deliver multimodal lifestyle recommendations tailored to each participant's psychological and behavioural profile. Study Objectives Primary objective: To determine whether digital personalisation and professional coaching improve adherence to a lifestyle-optimisation intervention. Secondary objectives: 1. Evaluate whether personalisation delivered through the ToBrainHealth platform increases adherence compared to generic, non-personalised education. 2. Assess the added value of intensive health coaching when combined with a personalised digital intervention. 3. Measure clinical impact via pre- and post-intervention medical, neuropsychological and psychosocial assessments. 4. Assess feasibility and acceptability of the ToBrainHealth platform as a remote monitoring and intervention tool. 5. Analyse adherence patterns and identify demographic, psychological and motivational factors influencing response to different intervention intensities. Study Design This is a controlled, three-arm intervention trial lasting 8 weeks. A total of 120 participants will be selected from the BBHI cohort among those classified into the High-Risk and Moderate-Risk latent profiles based on recent lifestyle, personality, and psychological questionnaires. Sixty individuals from each risk profile will be randomly selected. They will then be pseudo-randomised, stratified by age and biological sex, and psychological profile into one of the three study arms (n=40 per arm). Allocation will be concealed until the first visit, where each participant receives the appropriate study documentation. Intervention Arms 1. Control group - Generic lifestyle education (no technology) Participants receive non-personalised educational materials on healthy lifestyle habits. They periodically complete online questionnaires but do not receive any personalised recommendations or digital-driven adaptive strategies. 2. Personalised Digital Intervention - ToBrainHealth platform (no personal coach) Participants use the ToBrainHealth platform, a technology-based solution developed by Institut Guttmann and the Universidad Politécnica de Madrid, which allows: * Personalised lifestyle recommendations based on behavioural and psychological profiles. * Adaptive intervention strategies that evolve according to user engagement and progress. * Remote, asynchronous monitoring of behavioural changes. * Integration of multimodal lifestyle information (cognitive activities, nutrition, sleep, socialisation, psychological state, physical activity). Participants also wear a Fitbit HR device, synchronised with the platform to collect activity and sleep metrics. The device is loaned exclusively for study participation and must be returned upon completion. 3. Personalised Digital Intervention + Intensive Coaching - ToBrainHealth platform This arm receives exactly the same personalised digital intervention described in Arm 2, complemented by intensive professional health coaching. Coaching aims to enhance motivation, address barriers to engagement, reinforce adherence, and support the adoption of long-lasting healthy behaviours. Outcome Measures Primary Outcome: Adherence Adherence is quantified as the percentage of recommended lifestyle actions completed during the 8-week intervention. The study will evaluate: * Whether personalised digital guidance enhances adherence compared to the generic control group. * Whether intensive coaching produces additional improvements beyond digital personalisation alone. Secondary Outcomes: Clinical Impact and Behavioural Change Before and after the 8-week intervention, all participants undergo standardised assessments, including: Medical evaluation * General health status, anthropometry (weight, height) and blood pressure. Neuropsychological evaluation * Computer-based tasks measuring attention, memory, processing speed and executive function. Motivational and lifestyle assessment \- Used to refine personalised recommendations and characterise motivational profiles. Results from these evaluations will be integrated with the extensive longitudinal information already available from the BBHI cohort, allowing analysis of changes in cognitive performance, psychological wellbeing and lifestyle patterns. Sample Size and Statistical Considerations The total sample size (n=120) reflects power calculations based on expected small-to-moderate intervention effects (d≈0.3) observed in previous coaching-based lifestyle studies. With α=0.05 and power of 80%, the required sample is \~110 participants; 120 are recruited to compensate for an estimated 10% attrition rate. Planned analyses include repeated-measures ANOVAs and general linear models to compare intervention effects within and between groups. Data Management and Confidentiality All data will be managed using dedicated REDCap electronic case-report forms. Data will be pseudonymised using unique participant codes. Identifiable information will be stored separately with restricted access and password-protected systems. Audit trails will document all modifications. Data export for statistical analysis will follow controlled procedures and comply with GDPR (Regulation EU 2016/679) and Spanish data-protection legislation (LO 3/2018). Fitbit data synchronisation requires explicit participant authorisation. Regular data backups and REDCap system audits are performed at Institut Guttmann to guarantee data integrity and security. Ethical Considerations Participants receive detailed written and verbal information about the study, including procedures, duration, potential risks, benefits, and data-protection safeguards. Participation is voluntary, and withdrawal may occur at any moment without explanation or consequences. No participant can be included without providing signed informed consent. The study protocol is submitted to the corresponding Research Ethics Committee (CER) prior to initiation, and any non-administrative protocol amendments require CER approval. Implementation Schedule The project includes: * Parallel implementation of the three intervention arms, including baseline assessments, 8-week intervention period and follow-up evaluations. * Data analysis and preparation of scientific publications. Expected Scientific and Societal Impact The ToBrainHealth digital solution aims to advance understanding of resilience mechanisms and behaviour-change processes relevant to brain health. By combining personalisation, remote monitoring, digital phenotyping and intensive coaching, the study aspires to produce evidence-based, scalable strategies for maintaining brain health across the lifespan. Findings are expected to inform the development of personalised preventive programmes and guide public-health approaches aimed at reducing long-term risk of cognitive decline in ageing populations.