Cardiovascular Fitness and Sleep, but not Physical Activity, are Associated with Improved Brain Functional Connectivity in Older Adults.

Abstract

Background Aging results in changes in resting state functional connectivity within key networks associated with cognition. Cardiovascular function, physical activity, sleep, and body composition may influence these age-related changes in the brain. Better understanding these associations may help clarify mechanisms related to brain aging and guide interventional strategies to reduce these changes. In a large (n = 398) sample of healthy community dwelling older adults we conducted cross sectional analyses of the relationship between several modifiable behaviors and resting state functional connectivity within the brain in key regions associated with cognition and emotional regulation. Additionally, maximal aerobic capacity with a graded exercise test, physical activity and sleep with accelerometers, and body composition with dual energy x-ray absorptiometry were assessed. Associations were explored both through correlation and best vs. worst group comparisons. Results Greater cardiovascular fitness, but not larger volume of daily physical activity, was associated with greater connectivity within the Default Monde and Salience Networks, both of which are key networks associated with aging. Better sleep, in terms of increased total sleep time, higher sleep efficiency and fewer nighttime awakenings was also associated with greater connectivity within multiple networks including the Default Mode, Executive Control, and Salience Networks. Higher body fat percentage was associated with increased connectivity in the Dorsal Attentional Network. Conclusion These findings confirm and expand on previous work indicating that, in older adults, higher levels of cardiovascular fitness and better sleep in terms of greater efficiency and less total awakenings, but not greater volume of physical activity or lower volume of body fat are associated with increased functional connectivity within key brain regions. Also, assessing sleep quality and quantity may be a useful tool for identifying potentially clinically meaningful declines in brain function.