| Sumario: | Purpose Variability in finger and hand movements required in choice reaction and psychophysical tasks increase with both normal and pathological cognitive aging and with traumatic brain injury. The same is true of walking. The hypothesis presented is that increased stride time variability in prescribed paths and movement path variability (path tortuosity) in free ambulation is an early indicator of cognitive decline and dementia, and a short-term predictor of fall risk. Method Research is selectively cited and reviewed to support the hypothesis. Results & Discussion Variability in performance of repetitive and complex manual tasks accounts for much of the observed age-associated slowing of response speed1,2. Performing simultaneous cognitive tasks slows walking in both normal and pathological cognitive aging1. When measured in prescribed paths, the slowing reflects greater variability in stride speed3. When measured in unrestricted ambulation where it is possible to simultaneously measure both movement path spatial variability (path tortuosity) and movement speed, increased greater path tortuosity is the important predictor of dementia4 and an increased risk for a movement related fall occurring within a week prior to the fall5. Path tortuosity is measured by Fractal Dimension (Fractal D) that ranges from one (walking in a straight line) to two (a random walk). The close temporal association of elevated path tortuosity and a subsequent fall makes this assessment of fall risk a useful addition to the use of other known risk factors for implementing medical and environmental interventions (Figure 1).
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