Participatory approaches are increasingly required and used in research. In this review, we examined the impact (benefits and disadvantages) of participatory dementia research on researchers as potential key actors to sustainably implement the participatory approach. Our aim was to provide information on how the participatory process could be improved. We conducted a systematic literature review covering the Cochrane Library, PsycNet, PubMed, Scopus, and Google Scholar. The inclusion criteria for publications were as follows: research (1) involving people with dementia as co-researchers, (2) including a description or discussion of the impact of participatory research for researchers, (3) published between 2000 and 2020, and (4) in English. We performed a quality assessment of the included publications. Our final review included nine publications; three categorized as high quality, five as medium quality, and one as low quality. Four of the publications categorized as high or medium quality implemented participation at the level of partnership, and two publications implemented participation at the level of delegated power. The beneficial impact of participatory dementia research on researchers consisted of an increased understanding of people with dementia that widened researchers' theoretical knowledge and perspectives and increased their competence in working with people with dementia. Disadvantages comprised the required additional effort and time as well as the difficulty of establishing a balanced relationship between researchers and co-researchers. Disadvantages may result from the lack of a definition and structure of participatory research and a lack of training on both sides. More well-designed and transparent methods of evaluating participatory research projects are needed.
Keywords: co-research; dementia; impact; neurocognitive disorders; neurodegenerative disorders; participatory research; patient and public involvement; systematic review.