Description

Background Dementia affects tens of millions of people and no curative therapy exists. Non-pharmacological interventions that are safe, scalable, and acceptable are therefore essential to delay decline and preserve functioning. Positive Psychology Interventions (PPIs) have shown promising effects on wellbeing and, more recently, on cognitive performance and neural markers in older adults with early cognitive decline. Positive Neuropsychology proposes that cultivating positive traits and eudaimonic wellbeing may support brain plasticity and cognitive control through multiple pathways, including increased engagement, motivation, and adoption of protective lifestyles. Building on this framework, the present trial tests an online, multi-component PPI tailored for adults with Subjective Cognitive Decline (SCD) or Mild Cognitive Impairment (MCI). The program is designed to be feasible, scalable, and low-risk, and to generate clinically relevant outcomes on cognition and brain functioning.

Objectives and Hypotheses Primary objective: determine whether the PPI produces greater improvements than Treatment As Usual (TAU) in (a) cognitive performance and (b) neurophysiological indices of brain functioning at post-intervention and at 9-month follow-up. Secondary objectives: evaluate effects on wellbeing and related psychosocial constructs (character strengths, mindfulness), and assess feasibility, adherence, and safety of online delivery. We hypothesize larger gains with PPI at 16 weeks and sustained benefits at follow-up, with potentially stronger effects in SCD than MCI.

Study Design and Setting Randomized, parallel-group, superiority behavioral trial with two diagnostic groups (SCD, MCI) recruited via Alzheimer Hellas. Within each cohort, participants are randomized 1:1 to PPI or TAU, yielding four arms (SCD-PPI, SCD-TAU, MCI-PPI, MCI-TAU). Randomization is concealed and performed by site personnel who are not involved in outcome assessment. The trial is minimal risk, uses no FDA-regulated products, and is approved by the Bioethics Committee of Alzheimer Hellas (Approval No. 99/5-6-2024). Outcome assessors are trained and, where feasible, blinded to assignment.

Participants Community-dwelling older adults with a documented diagnosis of SCD or MCI from Alzheimer Hellas according to site procedures are eligibl. Key capabilities include informed consent, sufficient sensory ability for testing, and access/ability to join online groups. Major neurological/psychiatric conditions that would confound outcomes, severe sensory impairment preventing testing, and concurrent participation in similar psychological programs during the trial are excluded. After consent, participants receive unique study IDs; identifiers are stored separately, with controlled access, and destroyed after data lock.

Intervention: Multicomponent Positive Psychology Program Delivery: weekly small-group videoconference sessions (\~60 minutes) for 16 weeks led by trained psychologists.

Assessment schedule and procedures

Assessments occur at four time points:

T0 baseline (pre-randomization); T1 mid-intervention (\~6 weeks); T2 post-intervention (\~16 weeks; primary endpoint); T3 follow-up (\~9 months post-T2). Attendance and home-practice adherence are tracked. Adverse events (AEs) are monitored each visit and during sessions per institutional policy.

Outcomes and Data Acquisition

Primary outcomes (analyzed from T0 to T3):

Cognitive performance: a composite derived from the REMEDES4Alzheimer computerized battery capturing episodic memory, working memory, attention subdomains, and executive functions, with minimized demographic bias.

Brain functioning: EEG and functional near-infrared spectroscopy (fNIRS) markers obtained during standardized cognitive tasks using harmonized acquisition and artifact-handling protocols.

Secondary outcomes: validated indices of wellbeing (PERMA-Profiler; PANAS) measured at all time points to model trajectories. Exploratory psychosocial measures include character strengths (VIA-114GR) and mindfulness (MAAS). Feasibility metrics include recruitment and retention, session attendance, and self-reported practice.

Sample Size and Power Four arms (SCD-PPI, SCD-TAU, MCI-PPI, MCI-TAU). A priori power calculations indicate a minimum of 32 participants per arm; target enrollment N=128.

Data management and quality control Data are captured on secure, password-protected platforms under unique study IDs; personally identifying information is maintained in a separate, access-restricted file. Quality procedures include range and logic checks, double verification of key variables, and standardized preprocessing pipelines for EEG/fNIRS feature extraction. After database lock, the re-identification log is destroyed. De-identified data may be shared as described in the IPD plan.

Statistical analysis Analyses follow the intent-to-treat principle with participants analyzed as randomized. For longitudinal outcomes, linear mixed-effects models estimate change and Arm×Time interactions, with random intercepts for participants and adjustment for diagnosis cohort (SCD/MCI) and prespecified covariates (e.g., age, sex, baseline value). The two primary outcomes will be tested with appropriate multiplicity control. EEG/fNIRS features are derived via prespecified pipelines and analyzed analogously. Exploratory mediation models will assess whether changes in mindfulness or strengths use relate to cognitive and neural changes.

Safety and ethics Risks are minimal (time burden; potential fatigue during EEG and fNIRS). Standardized procedures and scheduled breaks mitigate burden. AEs are recorded, assessed for relatedness and severity, and reported to the ethics committee per policy. The study complies with the Declaration of Helsinki and applicable data-protection laws.

Implementation and expected impact Remote delivery enhances access for older adults with mobility or caregiving constraints and lowers cost for participants and providers. If efficacious, the program can be scaled across community and clinical settings through brief facilitator training and manualized materials. The trial will provide mechanistic evidence on whether cultivating character strengths and mindfulness improves cognitive functioning and alters neural activity in early decline. Demonstration of sustained benefits at nine months would support PPIs as practical, low-risk adjuncts to usual care for SCD and MCI, with potential to delay progression.

Follow-up and data sharing All participants are invited to T3 follow-up to assess durability. De-identified datasets may be shared on reasonable request after publication, subject to approvals and data-use agreements, consistent with the IPD sharing plan.