Slow Walking Signals Risk of Dementia

by Michael Smith for MedPage Today:In the oldest of old people, poor performance on physical tasks is associated with an increased risk of dementia, researchers reported.In a cross-sectional study of people 90 and over, such things as slow gait and impaired balance predicted dementia, according to Szofia Bullain, MD, and colleagues at the University of California Irvine. The findings suggest that dementia is a complicated process that may affect both cognition and physical performance, Bullain and colleagues reported online in Archives of Neurology.One implication, they concluded, is that physical performance may be "a potentially modifiable risk factor for late-age dementia." The researchers observed the "most notable effect" involved walking. Those who were unable to walk (and therefore scored 0) were almost 30 times more likely to have dementia than people with the fastest walking time.But they cautioned that -- because of the nature of the study -- it's impossible to tell which comes first, the physical or mental disability. A longitudinal study now under way, they noted, may help clear up that issue.The findings come from the so-called 90+ Study, which includes 847 participants, in a longitudinal epidemiologic study of aging and dementia.For this analysis, the researchers recruited 629 people, with an average age of 94, who had a complete neurological exam and completed four physical performance tasks -- a timed 4-meter walk, five chair stands, standing balance, and grip strength.Each of the tasks was scored from 0 to 4, with 4 being in the top quartile of performance and 0 being unable to complete the task.For the walk, participants were asked to walk along a marked path at their usual pace and were timed in seconds. Participants who could successfully fold their arms across their chests and stand from a sitting position were asked to do so five times as quickly as they could.For the balance tests, volunteers were asked to stand with their feet in a side-by-side position for a score of 1, then with the heel of one foot beside the big toe of the other for a score of 2. Finally, they were asked to stand with the heel of one foot directly in front of the other foot for 10 seconds each; they scored 3 if they could manage for up to 9. Participants were given a score of 3 if they held the pose for 1 through 9 seconds and 4 if they managed 10 or more.Grip strength was measured with a dynamometer and averaged over three trials.Bullain and colleagues found that, for each task, poor performance was linked to increased odds of dementia in a dose-response fashion."Even minimal impairment in the physical performance measures resulted in increasing odds of dementia," they reported, "and the odds of dementia continued to increase steadily with poorer performance in each task."Specifically, every unit decrease in physical performance score increased risk of dementia by a factor of:

• 2.1 for the 4-meter walk.
• 2.1 for the chair stands.
• 1.9 for standing balance.
• 1.7 for grip strength.

The researchers noted that even slightly slower walking speed -- from a score of 4 to 3, a difference of no more than 1.5 seconds -- was associated with a fourfold increase in the odds of dementia, which was significant at P=0.002, Bullain and colleagues reported.The finding has several possible explanations, the investigators noted. For instance, both physical and mental declines could be aspects of the same process, but the impairments might be detected at different times.Or, they noted, it could be that a decline in activity leads to poorer physical performance, which then contributes to cognitive impairment. That notion implies that physical performance might be a modifiable risk factor for dementia, they commented.Source: http://www.medpagetoday.com/Geriatrics/Dementia/35493