Cognitive Outcomes Following Physical Activity Interventions Incorporating Co-Design: A Systematic Review of...

Dementia and cerebrovascular dysfunction are growing public health challenges. Although physical activity can improve brain health, real-world adherence remains low. Co-design aims to enhance intervention relevance and engagement. This systematic review evaluated cognition outcomes following physical activity interventions incorporating co-design and determined whether cerebrovascular function was assessed. Six databases were searched until 28 August 2026 in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and PROSPERO registration (CRD420261279510). Eligible studies investigated cognition or cerebrovascular function following co-designed physical activity interventions in adults. Methodological quality was assessed using the Joanna Briggs Institute Critical Appraisal Tool, and findings were synthesised narratively. Of 757 records identified, four randomised controlled trials involving 315 participants were included. Co-design approaches varied, and adherence was favourable in three studies but lower in the refugee camp-based intervention. Global cognition and memory showed the most promising findings, although statistically significant intervention effects were limited to one study. Executive function, attention and working memory showed no consistent changes. No study assessed cerebrovascular function. Physical activity interventions incorporating co-design produced promising but inconsistent cognitive outcomes, but the independent contribution of co-design could not be determined. Future trials should integrate cerebrovascular function and cognition assessments to clarify mechanisms and determine whether co-design provides benefits beyond conventional intervention development.