1. A decline in gait speed paired with domain-specific cognitive decline proved to be strongly correlated with subsequent development of dementia over a six-year period.
Level of Evidence Rating: 2 (Good)
Study Rundown: Dementia is an increasingly common and poorly understood neurocognitive disease associated with significant slowing of mental and physical functioning. The present study sought to assess changes in gait speed and changes in cognitive function over time in order to understand the degree of accuracy with which physical slowing mirrors and predicts mental slowing in dementia patients. Data from a total of 15,309 participants were collected and analyzed in this study; mean age at study enrolment was 75.0 years and participants were followed for a median time of 4.5 years. Patients with dual gait decline and cognitive decline were found to be at a significantly higher risk of developing dementia compared with those who did not decline in either domain, and than those who declined in either gait or cognition alone. This was true in all four domains of cognition assessed (memory, global cognitive function, processing speed, verbal fluency). This study by Collyer et al retrospectively analyzed a large cohort of seniors and determined that a decline in both cognitive function and gait over time is predictive of a dementia diagnosis. In a practical sense, this work suggests that screening for gait speed and cognition in elderly patients may lead to earlier detection of dementia and possibly earlier initiation of therapy. Strengths of this study include the large sample size and the magnitude of the effect size. A major limitation of this work is that the participants were considered healthier than average elderly patients in the general population due to strict eligibility criteria for the trial, which limits the external validity of these findings.
In-Depth [retrospective cohort study]: A retrospective cohort study was conducted. Data were collected from the ASPREE trial, which evaluated the benefit of low-dose aspirin in elderly patients free from dementia (and other comorbidities) at baseline. Gait speed was measured at baseline, and at years 2, 4, and 6 thereafter, as well as at the study end visit in 2017. Cognitive function was assessed at baseline and at years 1, 3, 5 and study end using the following tools: 3MS for global cognitive function, delayed free recall, processing speed & verbal fluency. An outcome of “significant cognitive concern” was defined by one of the following: (3MS score below 78 or 10.15 points below predicted score; report of memory concerns to specialist, clinician diagnosis of dementia, prescription of cholinesterase inhibitors. The hazard ratios for developing dementia in patients who demonstrated dual gait and cognitive decline in the following cognitive domains as opposed to non-decliners were: 22.2 (95% confidence interval 15.0-32.9) for global cognitive decline, 24.9 (16.3-37.3) for memory, 4.3 (3.2-5.8) for processing speed and 4.7 (3.5-6.3) for verbal fluency. In all four cognitive domains, the hazard risk for dual decline was much greater in magnitude than either decline in cognition only, or decline in gait only (p < 0.001). In a Cox model adjusted for age, education, gender and country, higher baseline gait speed was associated with a significantly reduced risk of dementia (p < 0.001).
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