PREPRINT: Mechanisms of Motoric Cognitive Risk – hypotheses based on a systematic review and meta-analysis of longitudinal cohort studies of older adults

We aimed to refine the hypothesis that Motoric Cognitive Risk (MCR), a syndrome combining measured slow gait speed and self-reported cognitive complaints, is prognostic of incident dementia and other major causes of morbidity in older age. We propose mechanisms on the relationship between motor and cognitive function and describe a roadmap to validate these hypotheses. We systematically searched major electronic databases from inception to August 2021 for original longitudinal cohort studies of adults aged ≥60 years that compared an MCR group to a non-MCR group with any health outcome. Fifteen cohorts were combined by meta-analysis. Participants with MCR were at an increased risk of cognitive impairment (adjusted hazard ratio [aHR] 1.76, 95%CI 1.49-2.08; I2=24.9%), dementia (aHR 2.12, 1.85-2.42; 33.1%), falls (adjusted Relative Risk 1.38, 1.15-1.66; 62.1%), and mortality (aHR 1.49, 1.16-1.91; 79.2%). The prognostic value of MCR is considerable and mechanisms underlying the syndrome are proposed. Keywords: Motoric cognitive risk, gait, dementia, review, meta-analysis, mechanism, pathophysiology, falls, mortality, subjective cognitive complaint, prognostic, prevention Systematic review registration: PROSPERO CRD42020225183.