Researchers here investigate detailed measures of brain function over time, and correlate them with the level of physical activity. There is plenty of evidence for greater physical activity to slow cognitive decline with age and reduce the risk of dementia. Which of the many mechanisms involved are the most important is an open question: is it as simple as better vascular function to supply the brain with the nutrients it needs, or are more direct effects on neural mechanisms just as relevant?
Although various studies have identified physical activity as a possible primary preventive protective factor for brain health, the mechanisms by which physical activity affect cognitive function are not fully understood. Until recently, it was thought that physical activity was beneficial to brain health by means of reducing the impact of known risk factors, such as cardiovascular and cerebrovascular disease, stroke, or diabetes. However, there is a growing body of literature from human and animal studies that indicates that the benefits may be more direct, involving the promotion of synaptogenesis, neuroplasticity, and growth and survival of neurons, as well as the reduction of inflammation and stress.
The field of cognitive aging is constantly seeking more reliable biomarkers that accurately reflect the brain's functioning. Functional connectivity (FC) is one factor that has been reported to be affected by the aging process. It is thought to reflect typical cognitive changes in aging. Previous literature has documented disruptions in major large-scale networks during aging in the absence of disease; however, these findings have focused mostly on the default mode network (DMN) and its connections to other regions.
In the present study, we examined the longitudinal relationship between FC and self-reported changes in physical activity in community-dwelling older adults. Given that the DMN, the frontal-parietal network (FPN, also known as the central executive network), and the subcortical network (SN) are widely-examined networks that are associated with abilities such as introspection, executive function, and motor function, respectively, we focused our preliminary investigations on connectivity within these three networks.
We found that specific within-person increases in physical activity may track closely with FC. Importantly, there appears to be specificity regarding the regionality of this effect. Our findings suggest that within-person increases in physical activity are specifically associated with greater frontal-subcortical and within-subcortical network synchrony. Increased FC in these networks may further support the positive effect of physical activity on brain health markers.