Measuring the Influence of Physical Activity and Fitness on Development of Cognition, Brain Structure, and Brain Function in Periadolescent Children

Alzheimer’s disease (AD) is often considered a disease of old age, but new evidence suggests that modifiable lifestyle factors may impact disease processes long before clinical symptoms appear. Physical activity and fitness (PAF) are modifiable factors that are essential for brain health and cognitive function throughout the lifespan, from early childhood to late adulthood. PAF may influence the early development of cognitive and brain systems that are susceptible to late life, age-related decline, including memory, executive functions (EFs), and the hippocampus. In older adults, PAF has been strongly associated with cognition, brain structure, and brain function, but the impact of these factors on developing brain trajectories remains under-characterized. The current project investigated the relationship between PAF, cognition, brain structure, and brain function in a cohort of periadolescent children (N=121, ages 8-17 years) using an AD lens to understand how early-life factors influence systems later vulnerable to AD. Physical activity (PA) was measured via accelerometry, while fitness was characterized using grip strength (anaerobic) and the PACER test (aerobic). Participants completed a battery of cognitive tests to assess memory and EFs, and structural and functional MRI quantified hippocampal subfield volumes and resting-state functional connectivity (RSFC) of the hippocampus. Findings revealed that aerobic fitness was associated with relational memory ability, such that periadolescents with higher fitness outperformed those with lower fitness. PA was significantly associated with EFs, specifically cognitive flexibility. PAF was also associated with greater DG volumes following a curvilinear trajectory. Finally, higher aerobic fitness was associated with increased connectivity between the hippocampus and the somatomotor network, while lower aerobic fitness was associated with greater between-network connectivity. Greater levels of PA were associated with increased connectivity with the frontoparietal network (FPN). The results from this project suggest that PAF are differentially related to cognition and brain function in development but uniquely related to DG volume in this age range. These findings provide a novel framework for understanding the role PAF plays on the developmental trajectories of cognitive and brain systems, and how they might be leveraged in early life to reduce the risk of age-related diseases, including AD.