Motor and Cognitive Trajectories Before Dementia: Results from Gait and Brain Study.

ObjectivesDesignTo compare the trajectories of motor and cognitive decline in older adults who progress to dementia with the trajectories of those who do not. To evaluate the added value of measuring motor and cognitive decline longitudinally versus cross-sectionally for predicting dementia. Prospective cohort study with 5 years of follow-up. SettingParticipantsClinic based at a university hospital in London, Ontario, Canada. Community-dwelling participants aged 65 and older free of dementia at baseline (N=154). MeasurementsResultsWe evaluated trajectories in participants' motor performance using gait velocity and cognitive performance using the MoCA test twice a year for 5 years. We ascertained incident dementia risk using Cox regression models and attributable risk analyses. Analyses were adjusted using a time-dependent covariate. Overall, 14.3% progressed to dementia. The risk of dementia was almost 7 times as great for those whose gait velocity declined (hazard ratio (HR)=6.89, 95% confidence interval (CI)=2.18-21.75, p=.001), more than 3 times as great for those with cognitive decline (HR=3.61, 95% CI=1.28-10.13, p=.01), and almost 8 times as great in those with combined gait velocity and cognitive decline (HR=7.83, 95% CI=2.10-29.24, p=.002), with an attributable risk of 105 per 1,000 person years. Slow gait at baseline alone failed to predict dementia (HR=1.16, 95% CI=0.39-3.46, p=.79). ConclusionConceptual framework for association between motor and cognitive decline in aging and neurodegeneration. Cognitive function and gait performance decline with aging, leading to dementia and falls. Emerging research supports the view that cognition predicts not only dementia incidence, but also mobility decline and falls, whereas mobility decline and slow gait predict cognitive deterioration and progression to dementia. These simultaneous declines may occur because of burden in shared common brain networks. Grey arrows: cognitive impairment predicts dementia, with mild cognitive impairment (MCI), vascular cognitive impairment (VCI) and MCI in Parkinson' disease (MCI-PD) as intermediate states. Gait impairments increase fall risk, and slow gait mediates this association. White arrows show associations between cognitive and gait impairment, and dementia and falls, respectively (arrow thickness represents strength of association). Red: factors and diseases damaging brain areas and brain network integrity. Dotted lines: (a) cognitive impairment can predict falls and fractures, (b) motor impairment can predict dementias. From Montero-Odasso et al. Motor decline, assessed according to serial measures of gait velocity, had a higher attributable risk for incident dementia than did cognitive decline. A decline over time of both gait velocity and cognition had the highest attributable risk. A single time-point assessment was not sufficient to detect individuals at high risk of dementia. See related editorial by .