Subtle changes in the way a person walks can be an early warning sign of cognitive decline and a signal for advanced testing, researchers reported Sunday at the Alzheimer's Association International Conference in Vancouver, Canada.
The findings are the first to link a physical symptom to the disease, which up until now required doctors to begin a diagnosis by focusing on cognition and administering lengthy neurological exams. The evidence in the five studies is "robust," experts say. They note walking changes can occur even before cognition decline surfaces.
The presentation on the opening day of a week of meetings follows a plan the U.S. government announced in May to help train doctors in earlier detection and to find a cure by 2025.
"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," says Bill Thies, chief medical and scientific officer for the Alzheimer's Association.
The disease afflicts 5.4 million in the USA, and the number is forecast to spike to 16 million in 2050 as Baby Boomers age.
"Walking and movements require a perfect and simultaneous integration of multiple areas of the brain," says Rodolfo Savica, author of a study at the Mayo Clinic in Rochester, Minn.
Walking changes occur because the disease interferes with the circuitry between areas of brain. Savica ruled out other diseases, such as Parkinson's and arthritis, as possible causes.
In the Mayo Clinic study, researchers measured the stride length, cadence and velocity of more than 1,341 participants through a computerized gait instrument at two or more visits roughly 15 months apart. Those with lower cadence, velocity and length of stride experienced significantly larger declines in global cognition, memory and executive function.
"These changes support a possible role of gait changes as an early predictor of cognitive impairment," Savica says.
Another large study of 1,153 adults with a mean age of 78, by researchers at the Basel Mobility Center in Basel, Switzerland, found that gait became "slower and more variable as cognition decline progressed."
Participants were divided into groups based on cognitive diagnoses: cognitively healthy, mild cognitive impairment (MCI) or Alzheimer's dementia. Gait was measured using a walkway with 30,000 integrated sensors. Those with Alzheimer's walked slower than those with MCI, who walked slower than those who were cognitively healthy.
One annual test might not work with everyone, though. "You'd be surprised how many people say to me 'He doesn't walk that well at home' when I give them a gait test in the office," physician Lisa Silbert says.
Silbert conducted research on 19 dementia-free volunteers at Oregon Health and Science University in Portland. They measured gait speed during MRIs and gait speeds at home. Participants walked faster in the lab than at home. Slower in-home walking speed was associated with smaller total brain size. Dementias cause brain shrinkage.