Mild cognitive impairment is a known predictor of dementia, but not all the time —studies have shown that one-third of people whose memory and cognitive functioning have slightly declined do not progress to dementia but instead see their condition either remain stable or even improve.
Up until now, no clear method had been established to distinguish between the various forms of mild cognitive impairment (MCI), but researchers at the Lawson Health Research Institute and Western University in London, Ontario, have shown that a simple measure called the dual-gait test can effectively predict which cases of MCI are likely to progress to the more debilitating dementia. The finding will aid in the treatment and early diagnosis of dementia, researchers say.
The new study builds on the idea that, in the brain, thinking and cognition share the same neural networks as movement and motor control, notably in the prefrontal and temporal regions. These networks can become overloaded when having to deal with simultaneous tasks, say the researchers, an issue that is especially pronounced in people with cognitive impairment.
“While walking has long been considered an automatic motor task, emerging evidence suggests cognitive function plays a key role in the control of walking, avoidance of obstacles and maintenance of navigation,” says Dr. Montero-Odasso, geriatrician at St. Joseph’s Health Care London and associate professor in the Division of Geriatric Medicine at Western University and lead author of the study, in a press release. “We believe that gait, as a complex brain-motor task, provides a golden window of opportunity to see brain function.”
The dual-gait tests asks patients to walk at their usual pace (on a treadmill, in this case) while completing cognitive tasks such as counting backward from 100, subtracting by sevens from 100 and naming animals.
For the study, 112 older adults diagnosed with MCI were given both a “single-gait” test involving just the walking task as well as the dual-gait test. Researchers then followed up on the participants for a period of six years with biannual check-ups to assess neurologic, cognitive and gait functioning.
The study found that of the 112 participants, 27 progressed to dementia, with that cohort having recorded significantly lower dual-gait scores (measured by gait velocity and task responses) than the other participants. And importantly, as opposed to the dual-gait test, poor performance on the single-gait test did not turn out to be a predictor for progression to dementia.
“Our results reveal a ‘motor signature’ of cognitive impairment that can be used to predict dementia,” adds Dr. Montero-Odasso. “It is conceivable that we will be able to diagnose Alzheimer’s disease and other dementias before people even have significant memory loss. Our hope is to combine these methods with promising new medications to slow or halt the progression of MCI to dementia.”
About 564,000 Canadians are living with dementia, according to the Alzheimer’s Society of Canada, a number that is expected to increase by 66 per cent to 937,000 by the year 2031. While some forms of dementia are reversible, others including Alzheimer’s disease are not. Age is described as the biggest risk factor for dementia.
The new study is published in the journal JAMA Neurology.