Population-level interventions for dementia prevention: a systematic review.

Nearly half of dementia cases are potentially preventable through modifiable risk factors, yet few population-level interventions have been evaluated. This systematic review identified 12 studies from eight countries (Australia, Belgium, Chile, China, Denmark, the Netherlands, Puerto Rico, and the USA; sample size: 51-8360) evaluating population-level interventions focused on communicating dementia-specific risk reduction and prevention messaging. Intervention effectiveness varied. Mass media campaigns achieved broad reach but only marginal knowledge gains. Educational and interactive interventions, including personalised risk profiling, online courses, e-learning programmes, and community-based approaches, showed more consistent improvements in knowledge and risk-reducing behaviours. The most promising intervention combined risk assessment with structured education, achieving a 26% improvement in modifiable risk factor status over 3 years. Most studies had insufficient follow-up to assess long-term impact. Behaviour change barriers included insufficient knowledge and motivation and time and financial constraints. Future strategies should prioritise long-term engagement, co-design with under-represented communities, and scalable implementation across diverse populations.