Has dementia research lost its sense of reality? A descriptive analysis of eligibility criteria of Dutch dementia research protocols

Background/objectives: A substantial proportion of dementia patients are excluded from research participation, while for extrapolation of the study findings, it is important that the research population represents the patient population. The aim of this study is to provide an analysis of dementia research and its exclusion criteria in order to get a clearer picture whether the research participants represent the general dementia population. Methods: Dementia studies registered at ToetsingOnline.nl between 2006-2015 were analysed. Study characteristics, funding and eligibility criteria were described and analysed using a standardised score sheet. Results: The search yielded 103 usable study protocols. The number of trials has increased over the years, and 35% of the studies were industry-financed. Alzheimer’s disease was the most researched type of dementia (84%). In observational studies the most frequently observed exclusion criterion is a neurological condition, while in drug studies and other intervention studies this is a somatic condition. Of all protocols, 86% had at least one exclusion criterion concerning comorbidity. Most studies focused on mild or moderate dementia (78%). Conclusion: Our study has shown that the distribution of dementia research over the different subtypes of dementia does not correspond with the prevalence of these subtypes in clinical practice. The research population in the protocols is not representative of the larger patient population. A greater number of dementia patients could derive benefit from the conducted research if the research agenda were more closely aligned with disease prevalence. A better representation of all dementia patients in research will help to meet the needs of these patients.