Brain health measurement: a scoping review.

OBJECTIVES: Preservation of brain health is an urgent priority for the world's ageing population. The evidence base for brain health optimisation strategies is rapidly expanding, but clear recommendations have been limited by heterogeneity in measurement of brain health outcomes. We performed a scoping review to systematically evaluate brain health measurement in the scientific literature to date, informing development of a core outcome set. DESIGN: Scoping review. DATA SOURCES: Medline, APA PsycArticles and Embase were searched through until 25 January 2023. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies were included if they described brain health evaluation methods in sufficient detail in human adults and were in English language. DATA EXTRACTION AND SYNTHESIS: Two reviewers independently screened titles, abstracts and full texts for inclusion and extracted data using Covidence software. RESULTS: From 6987 articles identified by the search, 727 studies met inclusion criteria. Study publication increased by 22 times in the last decade. Cohort study was the most common study design (n=609, 84%). 479 unique methods of measuring brain health were identified, comprising imaging, cognitive, mental health, biological and clinical categories. Seven of the top 10 most frequently used brain health measurement methods were imaging based, including structural imaging of grey matter and hippocampal volumes and white matter hyperintensities. Cognitive tests such as the trail making test accounted for 286 (59.7%) of all brain health measurement methods. CONCLUSIONS: The scientific literature surrounding brain health has increased exponentially, yet measurement methods are highly heterogeneous across studies which may explain the lack of clinical translation. Future studies should aim to develop a selected group of measures that should be included in all brain health studies to aid interstudy comparison (core outcome set), and broaden from the current focus on neuroimaging outcomes to include a range of outcomes.