Dementia is a leading cause of death worldwide. Cognitive Stimulation Therapy (CST) is recommended to enhance cognition and quality of life in people with dementia. Despite clinical evidence, how CST works and why benefits vary remain unclear. Theories and early evidence suggest that the group- based, conversational nature of CST is key. Group diversity (differences among group members) may promote richer exchanges of ideas for cognitive stimulation, which can be reflected in lexical diversity (word variety in conversation). This research examines whether group diversity and lexical diversity help explains the benefits of CST.
Study 1 is a meta-analysis of individual participant data from multi-country CST studies (estimated
12 trials). By extracting group diversity markers (e.g., gender, education), their impacts on intervention outcomes will be evaluated using effect modification analyses.
The findings will inform Study 2, a feasibility randomised controlled trial of diverse versus
non-diverse CST in 56 participants, to understand the feasibility of arranging diverse CST groups
based on diversity markers, and estimate the effects of group diversity on cognition, quality of
life. A built-in intensive longitudinal data analysis using speech samples collected in CST
sessions will investigate whether group diversity predicts lexical diversity, and whether higher
lexical diversity during earlier intervention sessions predict further changes in lexical diversity
and outcomes over time, during the 7 weeks of CST and immediately after the intervention.
With public involvement throughout, this research will help guide CST practice internationally,
improve understanding of non-drug approaches in dementia care, and support better methods in
clinical research.