Changes in a person's gait, from slowing down to walking differently, could be an early indicator of mental decline, according to a handful of studies reported Sunday at the Alzheimer's Association International Conference 2012 in Vancouver, British Columbia.
"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 William Thies, Alzheimer's Association chief medical and scientific officer, in a news release about the research.
"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 said.
Alzheimer's disease afflicts at least 5 million Americans and predictions say as many as 16 million will have the disease in 2050 as Baby Boomers age, according to an Alzheimer's Association fact sheet. Cost associated with disease, it said, was $200 billion in 2012, including Medicare, Medicaid, out-of-pocket and other expenses.
An article in USA Today said the multistudy research presentation at the beginning of the week-long conference "follows a plan the U.S. government announced in May to help train doctors in earlier detection and to find a cure by 2025."
For one study, Dr. Stephanie A. Bridenbaugh of the Basel Mobility Center in Basel, Switzerland, and her colleagues used quantitative gait analysis, following 1,153 subjects, both cognitively healthy and those being treated as outpatients at a memory clinic. The average age of the study participants was 77.
They were divided into three groups: cognitively healthy, those with mild cognitive impairment and individuals with Alzheimer's dementia. Those with Alzheimer's were divided into subgroups of mild, moderate or severe. Gait was measured with a special walkway that was 10 meters long and had nearly 30,000 integrated pressure sensors. Participants walked as they normally would, then walked again counting backwards out loud and then again naming animals while walking.
Researchers found the gait slowed and was less consistent as cognitive decline advanced. And for all groups, speeds slowed when the subjects walked and did something else, compared to just walking.
"Mobility impairments are often associated with dementia, and some gait changes may even appear before cognitive decline can be detected by traditional testing methods. Gait analysis can simply, quickly and objectively measured (while) walking. When problems emerge, this may provide early detection of fall risk and the earliest stages of cognitive impairment in older adults," Bridenbaugh said. "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."
In another study, Dr. Mohammad Ikram and colleagues at Erasmus MC, Rotterdam, the Netherlands, examined cognition and gait in the elderly who live in a residential center. They used standardized neuropsychological tests to measure how fast each subject processed information, memory, fine motor speed and executive function. They also used an electronic walkway.
Each participant walked normally, then walked heel to toe, then turned. Researchers looked at gait variable using seven measures: rhythm, pace, phases, variability, step width and stride width, number of errors in a tandem walk and how long and how many steps it took each participant to turn around.
"Our results suggests that cognition and gait are tightly linked according to a specified pattern, in which certain cognitive domains only associate with corresponding aspects of gait," Ikram said.
In the patterns that emerged in the study, certain cognitive domains were only associated with certain aspects of gait. Information processing speed was linked with rhythm. Executive function was linked to pace and variability. Fine motor speed was associated with tandem.
A Mayo Clinic study indicates that walking changes happen because the neurodegenerative disease impairs communication between different parts of the brain. "Walking and movements require a perfect and simultaneous integration of multiple areas of the brain," study author Rodolfo Savica told the Detroit Free Press.
Mayo researchers measured the walk, including rhythm, speed and stride length, of more than 1,341 participants at intervals of about 15 months. Those whose gaits faltered in those measures had a great deal more overall cognition, memory and executive function decline.
An annual test may not tell the story, noted researcher Dr. Lisa Silbert of Oregon Health and Science University in Portland, who studied 19 cognitively-sound volunteers, measuring gait speed during MRIs and at home. Participants walked faster in the lab. Her research indicated an association between slower in-home speed over time and smaller volume of hippocampus, the section of the brain linked to memory.
"Walking speed taken at a single time point may overestimate walking abilities in the elderly," Silbert said. "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," she said in a release about the research.
Japanese researchers also noted a link between gait and mental ability. In a study from the Tohoku University Graduate School of Medicine in Sendai, Japan, researchers looked at 525 community-dwelling persons 75 and older, examining demographics, medical history and general physical and mental health. The subjects each walked as fast as they could for six meters while the scientists studied gait pattern, speed and stride length. Looking at MRIs, they found that gait velocity and atrophy in the entorhinal cortex, a kind of center in the brain that deals with memory and navigation, were closely related.
"Our research found that gait velocity was significantly decreased as the severity of dementia symptoms increased," said Kenichi Meguro, lead researcher. "Gait should no longer be considered a simple, automatic motor activity that is independent of cognition. They are linked."
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