Seniors who walk more slowly may have higher amounts of a protein linked to Alzheimer's in their brains, a small, new study suggests.
Researchers found a modest association between higher levels of amyloid plaques -- dense deposits of a protein known as beta amyloid -- and slower walking speeds among older adults.
"These results suggest that subtle walking disturbances, in addition to subjective memory concerns, may signal Alzheimer's disease, even in people who are fully asymptomatic and have a walking pace within the normal range," said study author Natalia del Campo, scientific manager of the Centre of Excellence in Neurodegeneration in Toulouse, France.
"Taking into account physical parameters that are not conventionally looked at in Alzheimer's disease, such as gait speed, may help optimize the early identification of patients at risk," added del Campo, who is also a postdoctoral fellow at the Gerontopole Research Centre in Toulouse.
The study was published online Dec. 2 in the journal Neurology.
More than 5 million Americans have Alzheimer's, an incurable, fatal disease that destroys memory, language, thinking and reasoning skills, according to the Alzheimer's Association. Increasingly, clinical research is focusing on spotting early signs of the disease that may go unconsidered prior to diagnosis.
The cross-sectional study, which allowed researchers to look at participants at one specific point in time, only establishes an association between brain amyloid levels and walking speed, but not a cause-and-effect relationship between the two, del Campo noted.
The research team analyzed 128 people (average age 76) who did not have a formal diagnosis of dementia but were considered at high risk because of memory problems. Brain scans measured amyloid plaque levels in their brains, with 48 percent registering a level often associated with dementia.
Additionally, participants underwent thinking and memory skills testing, with 46 percent classified as having mild cognitive impairment, a condition that can lead to Alzheimer's. Walking speed was measured using a standard test timing how fast participants walked 13 feet at their usual pace, and all but two tested within normal range.
The researchers found an association between slower walking speed and amyloid buildup in several areas of the brain, including a region known as the putamen, which is involved in motor function. Amyloid levels accounted for up to 9 percent of the difference in walking speed between faster and slower walkers, according to the study.
One expert said the findings make sense.
"The way you walk is influenced by systems of the brain that set the pace, so when this part of the brain isn't working properly, it may have an impact on gait or speed," said Dr. Joseph Masdeu, director of neuroimaging and the Nantz National Alzheimer Center at Houston Methodist Neurological Institute in Texas. "So, I'm not surprised by these findings."
But Masdeu, who wasn't involved in the study, cautioned that older adults who happen to walk more slowly than others shouldn't panic.
"You absolutely cannot tell somebody who is beginning to have difficulties walking that they have more amyloid in their brain," he said. "This is just a small contributor and many other systems can affect it, and many are age-related."
Masdeu and del Campo noted that several possible explanations exist for the observed link between brain amyloid levels and walking speed.
"It is possible that amyloid accumulation and slow gait speed co-occur as the result of a common lifestyle factor such as a deficient diet through childhood or adulthood, low physical activity or smoking," del Campo said. "It may also be explained by . . . diabetes or [high blood pressure]. We know that these are risk factors for dementia and poor motor function."
Dr. Eric Reiman, a spokesman for the American Federation for Aging Research, agreed with del Campo and Masdeu that more research is needed.
"This interesting study provides additional support for the idea that slower walking speed may be associated with the early stages of Alzheimer's disease," said Reiman, who is also executive director of Banner Alzheimer's Institute in Phoenix. "As the authors note, there are a number of factors that contribute to reduced walking speed in older adults.
"Additional studies are needed to clarify the extent to which slower walking speed could be used to help in the early detection and tracking of Alzheimer's, the prediction of subsequent clinical decline and the evaluation of investigational disease-modifying treatments," he added.
