According to the authors of a new study, monitoring changes in memory and walking speed over time may help identify those most at risk of dementia.
Dementia is predominantly associated with advancing age. So, as the average age of humans on planet Earth steadily rises, the burden of dementia is set to increase.
Currently, there is no cure; however, starting treatment early is associated with better outcomes. Because of this, researchers are focused on finding ways to predict who is most likely to develop dementia.
Also, certain factors increase the risk of dementia, including hypertension and sedentary behavior. Understanding which groups tend to develop dementia helps scientists and doctors identify and manage further risk factors.
One of the earliest symptoms of dementia is memory loss; however, many people experience cognitive decline with age, and this does not necessarily progress to dementia.
As a result, memory loss, on its own, is not a reliable way to predict dementia risk.
Some studies have concluded that slower walking speed, or slow gait, might also predict dementia risk. However, overall, it seems that the effect size is quite small and that gait speed alone is not a useful diagnostic measure.
Another study concluded that individuals whose memory and gait speed declined together were most at risk of developing dementia. But because this study included a relatively small group of individuals, all of whom had been admitted to geriatric clinics, it is not clear whether the results apply to the population at large.
With these findings in mind, a group of researchers set out to understand whether declining memory and walking speed, taken together, might be associated with increased dementia risk.
If their theory was correct, this so-called dual decline might become a useful way to predict those at most risk.
The researchers have published their findings in the journalGeriatrics.
For their investigation, the researchers combined data from six large-scale studies, including the Mayo Clinic Study of Aging and The Swedish National Study on Aging and Care in Kungsholmen Population Study.
The participants were all over 60. They completed memory tests, and their walking speeds were assessed.
At the start of the study, the scientists excluded anyone with preexisting cognitive impairment or dementia. They also excluded anyone with a particularly slow gait — slower than 0.6 meters, or about 2 feet, per second. After the exclusions, 8,699 individuals remained.
The authors compared participants with dual decline with those whose walking speeds and memory remained constant, whom they referred to as “usual agers.”
Across the six studies, the authors found that individuals who experienced memory decline had a 2.2 to 4.6 times higher risk of developing dementia than usual agers.
Among those who only had reduced gait speed, the risk of dementia increased by 2.1 to 3.6 times, and this effect was only statistically significant in three of the six studies.
When the scientists considered individuals who had both walking speed and memory decline, the results were more clearly defined. The researchers write:
“Participants with dual decline had 5.2 to 11.7 times higher risk of developing dementia, compared with usual agers.”
This effect remained significant even after controlling for a range of factors, including existing health conditions and the participants’ baseline walking speeds and memory performance.
Because early treatment for dementia improves outcomes, these findings are important. Both gait speed and memory are easy to assess, neither measurements are technology-reliant and both are low-cost. If further studies confirm these findings, adding these assessments to regular checkups would be relatively simple.
As the authors write, dual decline could be “captured early in clinical settings by routinely administering gait speed assessment and a free recall memory test.”
Future work should also address the question of why — what mechanisms are underpinning the dual decline? The authors believe that understanding why dual decline and dementia are connected might lead to future treatments or ways to prevent dementia from developing.
They also hope that additional research will examine “the particular metabolic, vascular, and neuroimaging features that characterize this specific group.”
Overall, the authors conclude that “Older persons with dual decline in memory and gait speed should receive further attention to address issues that may increase dementia risk, including evaluation of cardiovascular and metabolic risk factors.”