A study to be published in the Journal of Alzheimer’s Disease shows a correlation between low fitness, aortic stiffness, and the cognitive decline typically observed during brain aging .
Greater physical fitness is associated with reduced rates of cognitive decline in older people; however, the mechanisms by which this occurs are still unclear. One potential mechanism is aortic stiffness, with increased stiffness resulting in higher pulsatile pressures reaching the brain and possibly causing progressive micro-damage. There is limited evidence that those who regularly exercise may have lower aortic stiffness. To investigate whether greater fitness and lower aortic stiffness predict better cognitive performance in older people and, if so, whether aortic stiffness mediates the relationship between fitness and cognition. Residents of independent living facilities, aged 60–90, participated in the study (N = 102). Primary measures included a computerized cognitive assessment battery, pulse wave velocity analysis to measure aortic stiffness, and the Six Minute Walk test to assess fitness. Based on hierarchical regression analyses, structural equation modelling was used to test the mediation hypothesis. Both fitness and aortic stiffness independently predicted Spatial Working Memory (SWM) performance, however no mediating relationship was found. Additionally, the derived structural equation model shows that, in conjunction with BMI and sex, fitness and aortic stiffness explain 33% of the overall variation in SWM, with age no longer directly predicting any variation. Greater fitness and lower aortic stiffness both independently predict better SWM in older people. The strong effect of age on cognitive performance is totally mediated by fitness and aortic stiffness. This suggests that addressing both physical fitness and aortic stiffness may be important to reduce the rate of age associated cognitive decline.
It is well known that exercise is good for you and that, together with a healthy diet, it is the only sure-fire way currently available to slow down aging; our bodies simply aren’t made for the kind of sedentary lifestyle often observed today, which, under certain circumstances, can have dire consequences: obesity and heart disease, for example, and not necessarily only in old age.
If there ever was a need for more evidence that picking up physical exercise of whatever kind is something that everybody should do, this study from Swinburne’s Centre for Human Psychopharmacology provides it by explaining the relationship between fitness, aortic stiffness, and SWM. SWM can be thought of as a temporary storage area of the brain that is dedicated to processing information about the surrounding environment; thus, it is essential in navigating and orienting oneself.
Cognitive skills, including SWM performance, are generally better among older people with greater fitness, whose rate of cognitive decline is slower than for less-fit aged individuals. Why exactly this happens is not known, and the authors of this study wanted to figure out whether greater aortic flexibility might be a reason. The aorta is the main artery in the human body, and its stiffness and resulting higher pressure is thought to be a possible mechanism through which micro-lesions are inflicted on the brain, eventually leading to cognitive decline.
The scientists recruited 73 women and 29 men living independently in aged care communities; the subjects were then administered the six-minute walk test, which consists of participants walking back and forth between two markers 10 meters apart on a flat, unimpeded surface; participants are supposed to cover as much distance as possible in the allotted time. The researchers selected only the subjects who completed the full six minutes; the cognitive skills of the participants were then assessed using a computerized system.
Contrary to their expectations, the researchers did not find a correlation between greater physical fitness and arterial stiffness, but both metrics turned out to reliably and independently predict better cognitive performance—that is, participants who were more generally fit, or whose aortae had greater elasticity, had better cognitive skills than other participants; however, there was no evidence that greater fitness mediates its positive effects on cognitive skill through reduced aortic stiffness.
The researchers suggest that addressing both aortic stiffness and physical fitness may be important in mitigating cognitive decline in older age, even though the mechanisms through which these factors act is not yet clear.
Naturally, there are plenty of other reasons why staying fit and having a more elastic aorta are good ideas; they may postpone the onset of age-related conditions other than cognitive decline, thus not only improving your well-being but also increasing your chances of living long enough to benefit from future rejuvenation biotechnology.
 Kennedy, G., Meyer, D., Hardman, R. J., Macpherson, H., Scholey, A. B., & Pipingas, A. (2018). Physical Fitness and Aortic Stiffness Explain the Reduced Cognitive Performance Associated with Increasing Age in Older People. Journal of Alzheimer’s Disease, (Preprint), 1-10.