Dementia in multimorbidity: scoping review and priorities for research and care

Abstract

AbstractBackgroundMost people with clinical dementia have at least two other conditions. This co‐occurrence of multiple conditions, known as multimorbidity, is associated with worse quality of life, increased mortality and greater healthcare costs. However, there is limited research on the bidirectional interaction of physical multimorbidity and all‐cause dementia.We aimed to review and summarize key themes in this area, especially in the context of recent pharmacological advances.MethodWe searched PubMed and Google Scholar, updating the search strategy of a 2014 review of comorbidity and dementia. We added new key words reflecting recent trends in Alzheimer’s disease research, including: “amyloid”, “biomarker” and “disease‐modifying”. We searched the resulting papers’ references and citations and generated a narrative review of the literature grouped by research methodology.ResultSeveral key themes emerged from the published literature. Epidemiological studies confirmed that most people with dementia have multimorbidity. They additionally identified multimorbidity as a risk factor for dementia or cognitive impairment and found it to be associated with dementia progression and worse quality of life.Studies on the association between multimorbidity and biomarkers of neurodegeneration were either negative or found an inverse relationship. People with multimorbidity were found to be significantly under‐represented in clinical trials, especially those of dementia drugs.Qualitative research on healthcare delivery highlighted the importance of family carers and communication between providers, and a review of care coordination interventions identified important factors that optimize transitions of care.There was also recognition of the need to address racial and ethnic disparities in people with multimorbidity and dementia. Several papers called for a comprehensive understanding of dementia in relation to the whole person and society.ConclusionHaving multiple conditions alongside dementia poses challenges for patients, caregivers and clinicians. Multimorbidity is an important consideration for those designing representative clinical trials, and it may be more difficult to treat dementia in people with several comorbid conditions.This work highlights the need for specific research into the relative contributions of multimorbidity and other person‐centered characteristics on clinically meaningful outcomes. In the context of new and costly therapies, this will inform equitable allocation of research and healthcare resources.