Changes in gait, such as slower walking or a more variable stride and rhythm, may be early signs of mental impairments that can develop into Alzheimer’s before such changes can be seen on neuropsychological tests, said researchers at a conference this week. They suggest diagnosing changes in gait could alert doctors to begin testing for cognitive decline.
A cluster of studies presented at the 2012 Alzheimer’s Association’s International Conference (AAIC) that is taking place until 19 July in Vancouver, Canada, are the first to link physical changes to the disease. The researchers suggest changes in walking pattern may start to show even before cognitive impairments appear.
William Thies, Chief Medical and Scientific Officer of the Alzheimer’s Association, told the press that as the baby boomer generation approaches the age of higher risk for dementia and Alzheimer’s, doctors need to be increasingly aware of early signs.
“These studies suggest that observing and measuring gait changes could be a valuable tool for signaling the need for further cognitive evaluation,” said Thies.
“For busy doctors who have limited time with their patients, monitoring deterioration and other changes in a person’s gait is ideal because it doesn’t require any expensive technology or take a lot of time to assess. It is relatively simple and straightforward,” he added.
Linking changes in gait to cognitive impairment is not new: but until these studies, it has not been very clear which characteristics of gait (eg speed, rhythm or cadence, stride length) may be linked to a future cognitive decline.
In one of the studies, Rodolfo Savica and colleagues at the Mayo Clinic Study of Aging (MCSA) in the US, recorded the gait patterns of over 1,300 people at two different clinic visits, roughly 15 months apart.
During those visits, the participants also underwent a battery of neurological and neuropsychological tests that assessed four areas of mental functioning: memory, executive, language, and visuospatial. 158 of the participants were diagnosed with MCI (mild cognitive impairment), and 11 with dementia.
When the researchers analyzed changes in the participants’ patterns using GAITRite, a computer-based tool, they found those with lower cadence, speed and amplitude of stride length showed larger declines in overall cognition, memory and executive function:
“We observed an association between reduced gait velocity, cadence and stride length, and both global and domain-specific cognitive decline in our population,” said Savica.
“These results support a possible role of gait changes as an early predictor of cognitive impairment,” he added.
Another study conducted in Switzerland, that analyzed measures of gait characteristics, also suggested stride speed and variability may track cognitive impairment.
Stephanie A Bridenbaugh, of the Basel Mobility Center, and colleagues, followed over 1,150 outpatients of average age 77 who were attending the Basel Memory Clinic and Basel Mobility Center, plus a group of cognitively healthy volunteers who were taking part in a Basel cohort study, from 2007 to 2011.
The participants underwent gait analysis by walking on a 10-meter long electronic track that had nearly 30,000 inter-connected pressure sensors. They did three types of walking task: one single and two dual.
In the single walking task, all they had to do was just walk normally on the electronic track. In one dual task, they walked normally but also counted backwards out loud, and in the other, they walked normally and called out names of animals they were shown.
To analyze the data, the researchers put the participants in groups, according to diagnosis: cognitively healthy, mild cognitive impairment (MCI), and Alzheimer’s dementia (mild, moderate, and severe).
They found participants’ gait became slower and more variable as their cognitive function declined. For all groups, walking speeds were slower during the dual tasks compared to the normal single task.
Bridenbaugh said: “Those with Alzheimer’s dementia walked slower than those with MCI, who in turn walked slower than those who were cognitively healthy.”
“A gait analysis will not replace a comprehensive neuropsychological assessment to diagnose a patient’s cognitive status. Gait analysis, however, may prove to be an important tool to aid diagnosis, and record treatment effects or disease progression,” she added.
In another study, researchers at Erasmus Medical Center in Rotterdam, the Netherlands, found that certain cognitive functions were only associated with certain aspects of gait. For instance, speed of processing information was linked with gait rhythm, executive function was linked with pace and variability, while memory was not linked to any particular aspect of gait. Their research involved over 1,200 people over the age of 48 who were taking part in the the Rotterdam Study.
In a study from the US, researchers found that continuous in-home monitoring might be a more accurate way of assessing gait than single tests. Lisa Silbert, of Oregon Health & Science University in Portland worked with 19 dementia-free volunteers and found walking speed taken at a single time point may over-estimate walking ability in the elderly.
“Our data suggests that continuous in-home monitoring may provide a more accurate reflection of walking speed and may be more sensitive at detecting motor changes associated with future cognitive decline,” said Silbert.
Researchers at Tohoku University Graduate School of Medicine, Sendai, Japan found that gait velocity declined significantly as severity of dementia increased. In their study, involving 525 community-dwelling people age 75 and older in Japan, they also measured brain atrophy using MRI, and found atrophy of the entorhinal cortex, a region that serves as a hub in a widespread network for memory and navigation, was significantly linked to gait velocity.
Written by Catharine Paddock PhD