Gait (or walking) speed has been repeatedly associated with cognitive health in cross-sectional studies (studies that collect data at one point in time). Walking requires the coordination of multiple cognitive functions, so individuals with cognitive impairments will be expected to have, on average, a lower gait speed. While lower cognitive function is associated with poorer gait, the relationship over time between gait and cognition remains unclear. Does poor cognitive performance lead to subsequent slower gait? Can slower gait be used as an indicator of cognitive decline to come? A longitudinal study on gait speed and cognitive decline suggests that lower gait speed may be an indicator of later cognitive decline. In other words, decreased gait speed might point to the subsequent development of cognitive decline, which suggests that the clinical evaluation of gait speed among older adults may be used to identify risk for cognitive decline.
The study, published in the Journals of Gerontology, was conducted with 1,478 participants randomly selected from the entire population of individuals between the ages of 70 and 89 in Olmstead County, Minnesota. Participants were without dementia or clinically significant mild cognitive impairment (MCI) at the beginning of the study. At the study’s baseline, participants were given a neurological examination, assessed on various cognitive measures (such as visuospatial abilities and memory), and tested on their gait speed. This assessment was repeated on all participants every 15 months after baseline, with participants remaining in the study for a median of four years. The researchers were then able to answer two questions: whether lower gait speed at baseline predicted later cognitive decline, and whether cognitive ability at baseline predicted subsequent changes in gait speed.
When factoring in a set of relevant health and demographic variables and analyzing the changes over time of all participants, slower gait speed at baseline was associated with more rapid cognitive decline over the follow-up period in all areas of cognitive function. The researchers repeated their longitudinal analysis excluding the 320 participants who developed either dementia or MCI, and found that among all participants who remained clinically cognitively healthy, higher baseline gait speed was associated with better executive function and visuospatial skills over time, but was not associated with changes in memory. Conversely, lower cognitive ability at baseline was not associated with greater decline in gait speed over time, which the authors note conflicts with previous research which has suggested that lower cognitive function predicts subsequent declines in gait speed. The authors suggest that gait speed assessment be considered as a way to assess for the risk of cognitive decline.
Mielke MM, Roberts RO, Savica R, et al. Assessing the temporal relationship between cognition and gait: slow gait predicts cognitive decline in the Mayo Clinic Study of Aging. Journals of Gerontology, Series A: Biological Science and Medical Science (2013); 68(8): 929–937.