A Gray Matter Volume Covariance Network Associated with the Motoric Cognitive Risk Syndrome: A Multicohort MRI Study.

BACKGROUND: Motoric cognitive risk (MCR) syndrome is a predementia syndrome characterized by slow gait and cognitive complaint that predicts both Alzheimer's disease and vascular dementia. Yet, we know very little about the brain structures and brain pathologies associated with MCR. The aim of this study was to identify gray matter (GM) networks associated with MCR. METHODS: We used voxel-based morphometry and multivariate covariance-based statistics to identify GM networks associated with MCR in a pooled sample of 267 older adults without dementia from three different cohorts-two North American cohorts and one French cohort. RESULTS: The mean age of participants was 75.63 years, 50.56% identified as female, 57.68% had ≥13 years of education, and 5.99% had a prior history of stroke. A total of 14.23% participants met criteria for MCR. We identified a significant GM volume covariance pattern that was associated with MCR-even after adjusting for age, sex, education, mild cognitive impairment, stroke, total intracranial volume, and cohort status. This GM volume covariance network was primarily composed of supplementary motor, insular, and prefrontal cortex regions. CONCLUSIONS: These findings suggest that MCR is primarily associated with GM atrophy in brain regions previously linked to the control aspects of gait such as motor planning and modulation rather than the motor aspects of gait such as gait initiation and maintenance.