Recruitment and retention of older people with dementia in clinical trials focused on evaluating the pharmacological management of the cognitive symptoms of dementia: a scoping review.

OBJECTIVE: To investigate recruitment and retention of older people with dementia in clinical trials focused on evaluating pharmacological interventions for the treatment of cognitive symptoms of dementia. METHODS: A scoping review conducted using Joanna Briggs Institute methodological guidance. A systematic search of five databases and the International Clinical Trials Registry Platform was conducted from inception to July 2023, and updated in January 2025. Randomised controlled trials of any type in English were eligible if they included people ≥65 years, with a dementia diagnosis (any sub-type/stage), focused on pharmacological management of cognitive symptoms of dementia in any setting. Following screening and data extraction, findings were tabulated descriptively to present study characteristics and approaches to recruitment and retention. KEY FINDINGS: 131 trials were included. Reasons for participant exclusion were having no carer present (n = 131 studies), and using specific medications such as anticholinergics (n = 28 studies). A small number of studies (n = 12) provided limited details on recruitment approaches. Recruitment strategies ranged from clinical referrals by investigators and treating physicians to community advertising and the re-engagement of previous trial participants. Reporting of retention approaches was limited across included studies. The mean sample size was 427 participants, and the mean retention rate was 75.4%, with adverse events, carer unavailability and withdrawal of consent among the most commonly reported reasons for discontinuation. CONCLUSIONS: Trials involving older people with dementia may not provide generalisable findings due to recruitment and retention challenges. Future research should focus on overcoming these challenges and clearly reporting strategies that may be of benefit to other researchers.