Impact of different degrees of social engagement interventions (DDSEIs) on cognitive performance and brain activity in community-dwelling adults with subjective cognitive decline in Nanjing, China: a randomised controlled trial protocol.

introductionSocial isolation may have adverse effects on incidence and severity of cognitive impairment including subjective cognitive decline (SCD). An increase of environmental variety and social interactions may furthermore reduce progression from SCD to dementia. Research evaluating respective interventions is limited, particularly as regards studies comparing different degrees of social engagement interventions. We thus developed a clinical trial protocol to determine the efficacy of social interventions with different intensities in protecting cognitive function and white matter integrity in socially isolated adults aged 45-85 with SCD. METHODS AND ANALYSIS: This is a single-centre, three-arm randomised controlled trial with a 1:1:1 randomisation ratio, conducted from 1 December 2023 to 30 December 2026. The trial evaluates three study arms over a 12-week period: two social intervention arms (a social group intervention and a one-to-one social interaction intervention), both of which adopt a comprehensive model centred on social interaction and integrated with structured aerobic exercise and cognitive training; and a usual care arm in which participants receive only weekly health education. The sample size is estimated at 132 participants with SCD aged 45-85 years residing in Nanjing communities, China. Participants will be assigned to one of the three study groups via block randomisation stratified by gender. The principal outcome is improvement in mnemonic performance with delayed recall in the HuaShan version of the auditory verbal learning test between baseline and week 12. Secondary outcomes include improvement in white matter integrity measured by fractional anisotropy, along with changes in executive function, behavioural indicators and serum biomarkers assessed at baseline and week 12. Furthermore, follow-up evaluations with cognitive scales and serological data will take place at 3 months post-intervention. ETHICS AND DISSEMINATION: Ethical approval for this trial has been obtained from the Ethics Committee of the First Affiliated Hospital of Nanjing Medical University (approval No. 2023-SR-726.A1). Written informed consent will be secured from all participants before they are enrolled in the study. Findings from the trial will be submitted for publication in peer-reviewed academic journals. TRIAL REGISTRATION NUMBER: ChiCTR2400080312.