The researchers, including first author Dr. Claudine Gauthier and others from the University of Montreal, report their findings in the journal Neurobiology of Aging.
Dr. Gauthier, now a post-doctoral fellow at the Max Planck Institute for Human Cognitive and Brain Sciences in Germany, explains:
"Our body's arteries stiffen with age, and the vessel hardening is believed to begin in the aorta, the main vessel coming out of the heart, before reaching the brain. Indeed, the hardening may contribute to cognitive changes that occur during a similar time frame."
Older adults with more elastic aortas performed better on mental tests
She and her fellow researchers studied a group of older adults and found the ones whose aortas were in better condition and who were aerobically fitter did better on a cognitive test:
A group of older adults who were aerobically fitter performed better on a cognitive test, researchers say.
"We therefore think that the preservation of vessel elasticity may be one of the mechanisms that enables exercise to slow cognitive aging," she adds.
They studied two groups of physically and mentally healthy participants: 31 younger people aged 18-30 and 54 older adults aged 55-75.
They were interested in comparing not only the younger to the older group, but also to make comparisons within each age group.
All participants underwent physical and mental tests. For the physical tests, they worked hard on workout machines while the researchers measured their maximum oxygen intake over 30-second periods. And for the mental test, they performed a Stroop effect task - a scientifically validated test researchers often use to measure cognitive ability.
In the Stroop effect test, the participant is shown the names of different colors, such as RED, YELLOW, BLUE, and so on, with each word printed in a color that is not the color meant by the word. Thus, RED might be printed in blue, and YELLOW might be printed in red. The participant has to shout out the color of the print and not the printed word.
The participants also underwent three MRI scans: one measured blood flow to the brain, another measured brain activity during the Stroop task, and the third measured the stiffness of the aorta. The aorta is the largest blood vessel in the body - it carries oxygen-rich blood away from the heart to the rest of the body.
The researchers found evidence of age-related declines in brain executive function, elasticity of the aorta and cardiorespiratory fitness. They also found links between vascular health and brain function, and aerobic fitness and brain function.
Method could be adapted to study links in less healthy populations
Dr. Gauthier says this is the first study to report using MRI in this way:
"It enabled us to find even subtle effects in this healthy population, which suggests that other researchers could adapt our test to study vascular-cognitive associations within less healthy and clinical populations."
She notes that although other, more complex mechanisms may also link cardiovascular fitness and the health of blood vessels in the brain, "overall these results support the hypothesis that lifestyle helps maintain the elasticity of arteries, thereby preventing downstream cerebrovascular damage and resulting in preserved cognitive abilities in later life."
Funding for the study came from a number of sources, including the Canadian Institutes for Health Research, the Canadian Foundation for Innovation, the Canadian National Sciences and Engineering Research Council, and the Ministère du développement économique, de l'innovation et de l'exportation.
Meanwhile, in another recently published study led by Stanford University, Medical News Today learned how physical activity cuts the risk of irregular heartbeat in older women. The researchers found the more physically active the women were, the lower the chance they would develop atrial fibrillation, a heart condition that causes arrhythmia.