Of all human activities, few are so readily credited with enhancing the power of the mind as going for a good walk.
However, those who assume that strolling along at a gentle pace is the hallmark of superior intellect should think again, scientists have said.
In fact, based on a new series of experiments, they now believe the slower a person’s tendency to walk, the less able their brain.
Researchers performed gait-speed analysis on hundreds of middle-aged people, comparing the results with a range of physical and psychological measures.
Doctors have long used walking speed to gain a quick and reliable insight into older people’s cognitive capability, as it is increasingly recognized that gait is associated with not only musculoskeletal mechanisms but also the central nervous system.
Until now, however, no one knew it could signify underlying brain health so much earlier in life.
The correlation was so stark, however, that the US scientists now say walking tests could be used to provide an early indication of dementia.
Published in the Journal of the American Medical Association, the study revealed an average difference of 16 IQ points between the slowest and the fastest walkers at the age of 45.
This reflected both the participants’ natural walking speed and the pace they achieved when asked to walk as fast as they could.
Those with a slower gait also scored less well in both physical exercises, such as hand-grip strength and visual-motor coordination tests, as well as biological markers of poor health.
In the study, slower walkers were shown to have “accelerated aging” on a 19-measure scale devised by researchers, and their lungs, teeth and immune systems tended to be in worse shape than the people who walked faster.
The team at Duke University in North Carolina said genetic factors may explain the link between walking speed, brain capacity and physiological health, or that better brain health might promote physical activity, leading to better walking speed.
“The thing that’s really striking is that this is in 45-year-old people, not the geriatric patients who are usually assessed with such measures,” said Dr Line Rasmussen, who led the research.
The 904 New Zealand men and women who were tested at 45 were tracked from the age of three, each undergoing multiple tests over the years.
The long-term data collection enabled researchers to establish that toddlers with lower IQ scores, linguistic ability, capacity to tolerate frustration, motor skills and emotional control tended to have slower gait-speeds by middle age.
MRI exams during their final assessment at 45 showed the slower walkers tended to have lower total brain volume, lower mean cortical thickness, less brain surface area and higher incidence of white matter “hyperintensities”.
"In short, their brains appeared somewhat older," the researchers said.
Slower walkers were also judged to look older facially to a panel of eight assessors who determined each patient’s “facial age” from a photograph.
The researchers said some of the differences in health and cognition may be the result of lifestyle choices individuals have made.
But the study also suggests that there are already signs in early life of who would become the slowest walkers. “We may have a chance here to see who’s going to do better health-wise in later life,” said Dr Rasmussen.