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The findings have implications for ongoing early intervention research in Alzheimer disease and dementia since significant functional and neurocognitive declines were evident in middle age adults based on gait speed assessments.
Line Jee Hartmann Rasmussen, PhD
Gait speed at midlife is indicative of lifelong aging, including compromised brain integrity and brain health in childhood, according to results of a longitudinal cohort study published in JAMA Network Open.
A known indicator of advanced aging, age-related disease, and early mortality, gait speed sits at the intersection of musculoskeletal, visual, and central and peripheral nervous systems and serves as a marker of functional capacity. While most research has focused on the associations of gait speed with other functions in older adults, this study sought to identify the origins of gait and how midlife presentation may be indicative of accelerated biological aging.
The study, led by Line Jee Hartmann Rasmussen, PhD, of the department of psychology and neuroscience at Duke University, used data from the 5-decade Dunedin Multidisciplinary Health and Development Study. Ultimately 904 participants (50.3% male, 93% white) who were followed from birth on had gait speed measured at age 45 under 3 walking conditions: usual, dual-task, and maximum gait speed.
At multiple timepoints during the study period, participants’ physical function, aging, brain structure, and neurocognitive functioning was assessed. In addition, childhood neurocognitive function and socioeconomic status of their families was measured at age 3.
At midlife assessment, mean gait speeds were 1.30 (0.17) m/s for usual gait, 1.16 (0.23) m/s for dual task gait, and 1.99 (0.29) m/s for maximum gait. Participants with markers of impaired physical function and/or signs of accelerated aging had slower gait speed:
In addition, participants who had a lower IQ in midlife (β, 0.38; 95% CI, 0.32-0.44; P <.001), those who demonstrated childhood to adulthood cognitive decline (β, 0.10; 95% CI, 0.04-0.17; P <.001), and those with poor neurocognitive functioning at age 3 (β, 0.26; 95% CI, 0.20-0.32; P <.001) had slower gait at midlife. Specifically, picture vocabulary, receptive language skills, motor skills, and lack of control in childhood were significantly associated with midlife gait speed. These associations remained significant after controlling for childhood socioeconomic status.
Although “gait speed is used primarily to monitor the functional capacity of older adults and to forecast their rate of age-related decline…our findings suggest that gait speed may not only be a geriatric concern,” the investigators wrote. The findings demonstrate that midlife gait speed is already indicative of both physical and biological signs of accelerated aging, as well as lifelong compromised brain health and cognitive function.
Notably, the findings of this study, which focused on middle-age adults, parallel those of functional gait studies in older adults.
“These findings call for rethinking gait speed, from a geriatric index of functional decline to an index of the role of lifelong neurocognitive functioning in processes of aging,” they wrote.
As a result of the findings, the investigators proposed several hypotheses for ongoing research, including those exploring the role of health-promoting behaviors throughout life on total brain health. Moreover, the findings suggest that midlife gait speed may be a meaningful measure in aging-related studies aimed at preventing age-related disease, such as Alzheimer disease and dementia.
“It is increasingly recognized that it might be easier to prevent aging-associated damage than to reverse it, suggesting that the effect of interventions to slow aging may work better if they are applied while people are still young and free of disease and disability. This necessitates a shift toward enrolling younger participants in antiaging trials, and with this shift, valid measures are required to identify risk groups that need intervention, and to track the course of outcome before the manifestation of age-related diseases. Gait speed could be used as one such measure: the gait speed test is cheap, safe, easy to test repeatedly, and feasible to use among people in their 40s,” they concluded.
Hartmann Rasmussen LJ, Caspi A, Ambler A, et al. Association of neurocognitive and physical function with gait speed in midlife. JAMA Netw Open. Published online October 11, 2019. doi:10.1001/jamanetworkopen.2019.13123.