Walking more slowly as you age has always been a warning sign of increasing frailty that could lead to falls and other disabilities, experts say.
Now emerging research in small groups of elderly subjects has also found that a slower gait from year to year may be an early sign of cognitive decline.
Studies say that could be due to shrinking in the right hippocampus, which is the part of the brain associated with memory.
But not all signs of cognitive decline predict later dementia: only 10% to 20% of people age 65 or older with mild cognitive impairment or MCI develop dementia over the next year, according to the National Institute on Aging. “In many cases, the symptoms of MCI may stay the same or even improve,” the institute states.
Now, a large study of nearly 17,000 adults over age 65 finds people who walk about 5% slower or more each year, while also exhibiting signs of slower mental processing, were most likely to develop dementia.
The study was published in the journal JAMA Network Open.
“These results highlight the importance of gait in dementia risk assessment,” wrote corresponding author Taya Collyer, a research fellow at Peninsula Clinical School at Monash University in Victoria, Australia.
The study followed a group of Americans over 65 and Australians over 70 for seven years. Every other year, the people in the study were asked to take cognitive tests that measured overall cognitive decline, memory, processing speed and verbal fluency.
Twice every other year, subjects were also asked to walk 3m. The two results were then averaged to determine the person’s typical gait.
At the end of the study, researchers found the highest risk of dementia was for “dual decliners”, or people who not only walked more sluggishly but also showed some signs of cognitive decline, said Dr Joe Verghese, a professor of geriatrics and neurology at the Albert Einstein College of Medicine in Bronx, New York, who was not involved in the study.
"Furthermore, dual decliners had a higher risk of dementia than those with either gait or cognitive decline alone," Verghese wrote in an accompanying editorial published last wek in the JAMA journal.
A dual association between walking speed and memory decline is predictive of later dementia, a 2020 meta-analysis of nearly 9,000 American adults found.
Yet despite those findings, “gait dysfunction has not been considered an early clinical feature in patients with Alzheimer's disease”, Verghese wrote.
Exercise may help
There are things we can do as we age to reverse the brain shrinkage that comes along with typical ageing. Studies have found that aerobic exercise increases the size of the hippocampus, increasing some aspects of memory.
Buried deep in the brain's temporal lobe, the hippocampus is an oddly shaped organ that is responsible for learning, consolidating memories and spatial navigation, such as the ability to remember directions, locations and orientations.
Aerobic exercise training increased the volume of the right anterior hippocampus by 2%, thus reversing age-related loss in the organ by one to two years in a 2011 randomised clinical trial. In comparison, people who only did stretching exercises had an approximate decline of about 1.43% over the same time period.
Aerobic exercise means with “air”, and is a type of workout where heart rate and breathing increase, but not so much that you cannot continue to function. Types of aerobic exercise can include brisk walking, swimming, running, biking, dancing and kickboxing, as well as all the cardio machines at your local gym, such as a treadmill, elliptical trainer, rower or stair climber.
Study details
Association of Dual Decline in Cognition and Gait Speed With Risk of Dementia in Older Adults
Taya Collyer, Anne Murray, Robyn Woods, et al
Published in JAMA Network Open on 31 May 2022
Key Points
Question Which cognitive measure among global cognition, memory, processing speed, and verbal fluency is most useful in assessing risk of future dementia when combined with gait decline?
Findings In this cohort study of 16 855 relatively healthy older people in Australia and the US, a dual decline in gait and cognitive function compared with nondecliners was significantly associated with increased risk of dementia. This risk was highest in those with both gait and memory decline.
Meaning These results highlight the importance of gait in dementia risk assessment and suggest that dual decline in gait speed and a memory measure may be the best combination to assess future dementia.
Abstract
Importance
Dual decline in gait speed and cognition has been found to be associated with increased dementia risk in previous studies. However, it is unclear if risks are conferred by a decline in domain-specific cognition and gait.
Objective
To examine associations between dual decline in gait speed and cognition (ie, global, memory, processing speed, and verbal fluency) with risk of dementia.
Design, Setting, and Participants
This cohort study used data from older adults in Australia and the US who participated in a randomised clinical trial testing low-dose aspirin between 2010 and 2017. Eligible participants in the original trial were aged 70 years or older, or 65 years or older for US participants identifying as African American or Hispanic. Data analysis was performed between October 2020 and November 2021.
Exposures
Gait speed, measured at 0, 2, 4, and 6 years and trial close-out in 2017. Cognitive measures included Modified Mini-Mental State examination (3MS) for global cognition, Hopkins Verbal Learning Test-Revised (HVLT-R) for memory, Symbol Digit Modalities (SDMT) for processing speed, and Controlled Oral Word Association Test (COWAT-F) for verbal fluency, assessed at years 0, 1, 3, 5, and close-out. Participants were classified into 4 groups: dual decline in gait and cognition, gait decline only, cognitive decline only, and nondecliners. Cognitive decline was defined as membership of the lowest tertile of annual change. Gait decline was defined as a decline in gait speed of 0.05 m/s or greater per year across the study.
Main Outcomes and Measures
Dementia (using Diagnostic and Statistical Manual of Mental Disorders [Fourth Edition] criteria) was adjudicated by an expert panel using cognitive tests, functional status, and clinical records. Cox proportional hazard models were used to estimate risk of dementia adjusting for covariates, with death as competing risk.
Results
Of 19 114 randomised participants, 16 855 (88.2%) had longitudinal gait and cognitive data for inclusion in this study (mean [SD] age, 75.0 [4.4] years; 9435 women [56.0%], 7558 participants [44.8%] with 12 or more years of education). Compared with nondecliners, risk of dementia was highest in the gait plus HVLT-R decliners (hazard ratio [HR], 24.7; 95% CI, 16.3-37.3), followed by the gait plus 3MS (HR, 22.2; 95% CI, 15.0-32.9), gait plus COWAT-F (HR, 4.7; 95% CI, 3.5-6.3), and gait plus SDMT (HR, 4.3; 95% CI, 3.2-5.8) groups. Dual decliners had a higher risk of dementia than those with either gait or cognitive decline alone for 3MS and HVLT-R.
Conclusions and Relevance
Of domains examined, the combination of decline in gait speed with memory had the strongest association with dementia risk. These findings support the inclusion of gait speed in dementia risk screening assessments.
CNN article – Your walking speed could indicate dementia (Open access)
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