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Walking slower? You should test for Alzheimers

Vancouver: Gait disturbances —such as a slowing of walking pace or a more variable stride — could indicate a decline in cognitive function, according to new research studies reported on Monday  at the Alzheimer's Association's International Conference(R) 2012 (AAIC(R) 2012).

"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 signalling the need for further cognitive evaluation," said William Thies, PhD, Alzheimer's Association(R) Chief Medical and Scientific Officer.

"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," Thies added.

Gait analysis shows that changes in stride speed may help track cognitive impairment difficulties with walking are not inevitable consequences of aging. They are, however, common and relevant problems among older adults. Research shows that people with walking difficulties not only have an increased risk of falling, but may also have an increased risk developing memory disorders and dementia.

Stephanie A  Bridenbaugh, MD, of the Basel Mobility Center in Basel, Switzerland, and colleagues used quantitative gait analysis to explore this issue. The study followed 1,153 participants (average age 77) including outpatients from the Basel Memory Clinic and Basel Mobility Center, plus cognitively healthy participants in a Basel cohort study, from 2007 to 2011.

Participants were divided into groups based on their cognitive diagnoses: cognitively healthy, mild cognitive impairment (MCI) or Alzheimer's dementia.

Those with Alzheimer's dementia were subdivided into mild, moderate or severe.

Gait was measured using a 10-meter-long electronic walkway with almost 30,000 integrated pressure sensors. All participants performed one "normal" walk and two different "dual tasks" —normal walking while simultaneously counting backwards out loud or while simultaneously naming animals.

The scientists found that gait became slower and more variable as cognitive decline progressed. For all groups, walking speeds were slower during dual tasking than during normal walking alone. "Those with Alzheimer's dementia walked slower than those with MCI, who in turn walked slower than those who were cognitively healthy," said Bridenbaugh.

"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 measure walking.

When problems emerge, this may provide early detection of fall risk and the earliest stages of cognitive impairment in older adults," Bridenbaugh added. "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."

Researchers found that those with lower cadence, velocity and amplitude of the stride length experienced significantly larger declines in global cognition, memory and executive function

Specific aspects of gait may be associated with specific cognitive abilities and functions.

With ageing and in people with Alzheimer's disease, various brain functions deteriorate. Most research has focused on cognition. Recent evidence suggests that gait is also affected by aging and Alzheimer's, yet the exact relationship remains unclear.

Mohammad Ikram, MD, PhD, and colleagues at Erasmus MC, Rotterdam, the Netherlands investigated the relationship between cognition and gait in community-dwelling elderly. The researchers studied 1,232 individuals aged 49 and older from The Rotterdam Study (Note: data included here is updated since the original abstract submission to AAIC 2012).

Standardized neuropsychological tests were used to measure information processing speed, memory, fine motor speed, and executive function. Gait was assessed using an electronic walkway.

Each participant performed a normal walk, a tandem walk (where the heel of your front foot is placed directly touching the toes of your back foot), and a turn.

Gait variables were grouped into seven independent factors: Rhythm (reflecting stride time and cadence),  pace (reflecting stride length and velocity), phases (reflecting the amount of time spent on one or both feet), variability (reflecting the variation in gait within persons), base of support (reflecting step width and stride width), tandem (the amount of errors in a tandem walk) and turn (the amount of time and steps needed to turn around).

Interesting patterns emerged in the data analysis; the researchers found that certain cognitive domains were only associated with certain aspects of gait.

  • Information processing speed was associated with the Rhythm aspect of gait.
  • Executive function was associated with Pace and Variability.
  • Fine motor speed was associated with Tandem.
  • Memory was not associated with any aspect of gait.

"Our results suggest 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.

Reduced gait velocity, cadence, and stride length may be associated with cognitive decline.

Some previous studies have reported that gait abnormalities may be associated with cognitive impairment and dementing illnesses. However, it is unclear which gait components may be associated with a future cognitive decline.

Rodolfo Savica, MD, MSc, and colleagues at the Mayo Clinic Study of Aging (MCSA) measured the stride length, cadence and velocity of more than 1,341 study participants through a computerized gait instrument (GAITRite) at two or more visits roughly 15 months apart. The visits also included neurological and neuropsychological evaluations covering four
domains: Memory, executive functioning, language, and visuo-spatial ability. Participants were either cognitively normal (1,172), or diagnosed with MCI (158) or dementia (11).

The researchers found that study participants with lower cadence, velocity and amplitude of the stride length experienced significantly larger declines in global cognition, memory and executive function.

PRNEWSWIRE/ASIANET

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