Thinking About the Way We Move

Dr. Manuel Montero-Odasso is researching the connection between gait and cognition, as well as the potential effectiveness of lifestyle interventions that could limit the decline of both

For some, it might feel like walking requires no thought at all. But our gait — the technical term used to describe the way we move — isn’t automatic.

“Mobility and cognition decline together in aging. They interact. If I see a patient with mobility problems [or] fractures, it’s not uncommon that I detect undiagnosed cognitive problems,” says Dr Manuel Montero-Odasso, a geriatrician based in London, Ontario. “And when I see a patient with cognitive problems or pre-dementia, it’s not uncommon I diagnose mobility problems.”

Montero-Odasso has studied the connection between gait and cognition since the 1990s. He is a professor in the departments of medicine, and epidemiology and biostatistics at Western University. He is also the director of the Gait and Brain Lab at the Parkwood Institute, which he started in 2010, and where he researches how gait changes can be a predictor for dementia, as well as how non-invasive interventions might reduce the risk of mobility and cognitive decline.

The connection between gait and cognition

The same part of the brain — the frontal lobe — controls both complex cognitive processes, like language, problem solving and emotion regulation and how we control movement.

In an article published in the European Journal of Neurology, Montero-Odasso explains this connection in greater detail: “Cognitive function, especially executive function and memory, rely on frontal-hippocampal and thalamic-striatal circuits [in the brain], which also control gait, spatial orientation and navigation.”

Yet a changing gait does not lead to cognitive decline, nor does cognitive decline lead to changing gait. “We believe that both features are an expression of the same problem at the brain level,” explains Montero-Odasso, but adds that the specific mechanisms connecting the two are still not fully understood.

The early indicators of cognitive decline

Changes in movement that might indicate cognitive decline include a slowing gait and smaller, shuffling steps.

“But that doesn’t mean that everyone whose walk slows will [develop] dementia. And that doesn’t mean everyone who develops dementia will start walking slowly,” says Montero-Odasso. “Interestingly, in the ’90s we thought that gait problems were a late complication of dementia, but studies show that [gait] changes are actually earlier indicators of cognitive impairment.”

In fact, a decline in gait speed can precede cognitive decline by more than a decade. Through his research, Montero-Odasso incorporates something called dual-task testing. This assesses an individual’s risk of progressing from mild cognitive impairment to dementia.

“In dual-task testing, you put stress [on the activity of walking] by adding an extra cognitive task,” says Montero-Odasso. He tests his patients by having them walk up and down a corridor while simultaneously performing a cognitive task, like talking or doing calculations. Everyone’s gait will likely slow down during a test like this, but it’s the degree of change that can be an indicator of cognitive decline.

“We found that in people over 65, a slowing down in gait of more than 20 per cent [during a dual-task test] means those people in particular are more likely to [develop] dementia,” says Montero-Odasso.

He adds that if his patients decline in both gait speed and cognitive functioning, month by month over a six-month period, they are considered dual-decliners. A study he published earlier in 2020 in Age and Ageing found dual-decliners had a three-fold risk of progressing to dementia compared to non-dual decliners.

Can the risk of decline be reduced?

Currently, Montero-Odasso is leading a national trial to analyze the effects of combining physical exercise, cognitive exercises and vitamin D supplementation. His SYNERGIC Trial is tracking whether this combination of interventions could prevent both cognitive decline and mobility decline in adults living with mild cognitive impairment.

While the results of this trial — including recommended physical exercises, cognitive exercises and dosages for supplementation and exercise — aren’t released yet, Montero-Odasso says there are steps that can be taken to reduce one’s risk of both cognitive decline and mobility decline.

As well as incorporating dual-task gait assessments into any geriatric check-up, Montero-Odasso says that preventing mobility and cognitive decline should focus on lifestyle interventions. Emerging evidence shows up to 35 per cent of dementia cases could be prevented by modifying 12 lifestyle risk factors, one of which is physical inactivity.

“Sometimes you cannot prevent dementia entirely, but you can delay [some types] of dementia,” says Montero-Odasso. “I think today, treatment for dementia is prevention and that prevention should be lifestyle interventions: having a healthy diet, doing physical exercise and doing cognitive training. Right now, we don’t know how to prescribe that for older people, but we are in the state of research.” [ ]