Slight changes in the way a person walks, like slowing down or developing a variable stride, could be early signs of Alzheimer’s disease.
Previous studies have linked walking speed in the elderly with overall good health and even longevity, but the current research is among the first to associate gait with risk of Alzheimer’s. The four new studies, presented over the weekend at the Alzheimer’s Association International Conference in Vancouver, find that changes in physical movements like walking can even precede symptoms of cognitive decline
One study by researchers at the Basel Mobility Center in Switzerland followed 1,153 elderly participants including patients at the center being treated for memory and mobility problems as well as volunteers in a separate 2007-11 cohort study. The participants were separated into groups based on their cognitive status: cognitively healthy, diagnosed with mild cognitive impairment (MCI) or diagnosed with Alzheimer’s dementia.
Researchers tested the participants’ gait on a 33-ft. electronic walkway containing 30,000 integrated pressure sensors. The participants were tested for “normal” walking and for performance on two “dual tasks,” which included normal walking while simultaneously counting backward out loud or while naming animals.
Overall, everyone walked slower while attempting to multitask, but walking speed was also linked with people’s varying levels of cognitive decline. People with Alzheimer’s walked slower than those with MCI, who walked slower than cognitively healthy adults.m”Mobility impairments are often associated with dementia, and some gait changes may even appear before cognitive decline can be detected by traditional testing methods,” said lead study author Dr. Stephanie Bridenbaugh in a statement. “Gait analysis can simply, quickly and objectively measure walking. When problems emerge, this may provide early detection of fall risk and the earliest stages of cognitive impairment in older adults.”
In a second study by researchers at the Mayo Clinic, 1,341 participants were observed using a computerized tracking tool, which measured stride length, cadence (or steps per minute) and speed of walking. People were tested at least twice about 15 months apart. The researchers found that participants with lower cadence, speed and stride length were significantly more likely to show declines in global cognition, memory and executive function, compared with faster walkers.
Study researcher Dr. Rodolfo Savica told USA Today that “walking and movements require a perfect and simultaneous integration of multiple areas of the brain,” and walking changes happen when dementia interferes with the circuitry between various brain regions.
A third study by Kenichi Meguro of the Tohoku University Graduate School of Medicine and his colleagues also looked at the link between gait and cognitive function in 525 community-dwelling adults aged 75 and older in Japan. The participants had their gait patterns, velocity and stride length measured as they walked about 20 ft. at their fastest pace. As in the other studies, researchers found that people’s walking speed slowed down significantly as the severity of dementia symptoms increased. The study authors also found that degeneration of the patients’ entorhinal cortex, the section of the brain associated with memory and navigation, was significantly correlated with walking velocity.
“Gait should no longer be considered a simple, automatic, motor activity that is independent of cognition. They are linked,” said Meguro.
In one other study presented at the conference suggested that people’s true walking speed could more accurately be measured by tracking their activity at home rather than using a single test at the doctor’s office. Dr. Lisa Silbert of Oregon Health & Science University in Portland and colleagues studied 19 dementia-free adults, using MRI to measure the volume of the entire brain and various sections and also testing their walking speed. The researchers measured velocity in two ways: by timing participants as they walked about 30 ft. at the doctor’s office before undergoing MRI, and at home by using motion sensors that continuously collected walking data over a one-month period.
The researchers found that people tended to walk faster in the doctor’s-office test than they did at home. Further, slower walking speeds measured at home were more closely associated with smaller total brain size and smaller volumes of the hippocampus — a brain region crucial to memory processing — than the one-time walking speeds measured at the office.
“Walking speed taken at a single time point may overestimate walking abilities in the elderly,” said Silbert. “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.” Silbert said, noting that technology exists to allow doctors to measure patient’s walking speed in the real world.
“With an aging baby boomer generation advancing into greater risk for Alzheimer’s and dementia, it is important for physicians to be aware of the associations between gait and mental function. These studies suggest that observing and measuring gait changes could be a valuable tool for signaling the need for further cognitive evaluation,” said Dr. William Thies, chief medical and scientific officer of the Alzheimer’s Association, in a statement.
Gait measurements are inexpensive and don’t take a lot of time to assess, said Thies. Given the research, they could be a valuable way for busy doctors to identify early cases of cognitive decline. Tests of walking speed don’t take the place of comprehensive neurological exams for diagnoses of Alzheimer’s, but as Bridenbaugh points out, observing elderly patients’ gait could help doctors make such diagnoses and monitor the effects of treatment or disease progression.