Trajectories of gait and cognitive decline in aging, and as a function of parental longevity and the motoric cognitive risk syndrome

Abstract

AbstractBackgroundAccelerated gait decline in aging often precedes mild cognitive impairment, Alzheimer’s disease, and related dementias. The relative trajectories of gait and cognitive decline are poorly understood, particularly, in older adults who are a) more resilient to cognitive impairment because they are offspring of parents with exceptional longevity (OPEL) and, b) at increased risk for cognitive impairment and dementia because of the Motoric Cognitive Risk (MCR) syndrome. MCR is a pre‐dementia syndrome, characterized by slow gait and subjective cognitive complaints. We examined trajectories of gait and cognitive decline in older adults overall, and as a function of parental longevity and MCR.MethodLonGenity study participants (n=1,095; M Age=75.4±6.7 years) were followed for up to 12 years (M =6.6±3.4 years). Participants were of Ashkenazi Jewish descent and free of dementia at baseline. 53% were OPEL and 9% had MCR. Gait speed was measured on an instrumental walkway. Standardized performance on 13 different cognitive tests were examined separately, and as a composite global cognition score. Linear mixed‐effects models adjusted for baseline age, sex, education, cognitive impairment, and parental longevity were used to examine trajectories of gait and cognition over time – and as modified by parental longevity and MCR.ResultGait speed and performance on all cognitive tests (except phonemic fluency and digit span) declined with time. Gait speed (β= ‐0.076; 95% CI= ‐0.083‐0.070) declined faster than cognitive tests, including figure copy (β= ‐0.041; 95% CI= ‐0.050‐0.031), digit symbol substitution (DSST; β= ‐0.036; 95%CI= ‐0.041‐0.031), and trail‐making test interference (β= ‐0.032; 95%CI= ‐0.024‐0.040). Global cognition, DSST, and logical memory declined at a slower rate in OPEL. Figure copy performance declined at a faster rate in MCR.ConclusionThese findings suggest that 1) gait declines faster than most cognitive functions in aging, 2) OPEL are more resilient to cognitive decline in general, and processing speed/attention and memory in particular, and 3) individuals with MCR are more susceptible to visuo‐spatial and executive function decline. This study adds important knowledge of trajectories of gait and cognitive decline in aging, and identifies a protective factor and a risk factor of age‐related cognitive decline.