Neurotrophic and growth factor response to acute exercise across the lifespan

Abstract

AbstractBackgroundThere is evidence that aerobic exercise is beneficial to the brain and may reduce risk for cognitive decline and dementia. However, clinical trials have shown the benefits of exercise programs vary amongst individuals. This variability may occur in part due to differences in the physiological biomarker response to acute exercise. Characteristics such as age, sex, and apolipoprotein E4 (APOE4) genotype may affect these responses, but differences in blood processing protocols may introduce additional variability into the measures.MethodWe characterized the blood biomarker response to acute exercise in 80 individuals, including older adults (n=62, mean age 73y) and 18 young controls (n=18, mean age 37). Participants engaged in an acute, 15 minute bout of moderate intensity exercise (45‐55% HRR) following a 5 minute warm‐up. Blood was collected immediately prior to exercise, immediately post exercise, and 40 minutes post exercise. After collection, each timepoint sample was immediately processed for plasma and platelet poor plasma and frozen; this was done to limit release of growth factors from activated platelets post‐blood draw. Time course responses of brain derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), insulin like growth factor 1 (IGF1) were measured using ELISA in platelet poor plasma. Lactate was measured in plasma (YSI 2500).ResultLinear mixed modeling performed with age, sex, and APOE4 genotype as covariates revealed a significant change in BDNF (p<0.001) and lactate (p<0.001) over time, with the highest levels of lactate observed immediately post‐exercise, while BDNF was elevated at 40 minutes post‐exercise in both young and older adults. There was no significant change with either VEGF or IGF1 over time in response to exercise, although older adults had significantly higher VEGF (p=0.01) and lower IGF1 (p<0.001) compared to young controls across all timepoints.ConclusionWe report here that analysis of the acute exercise response reveals a significant increase in circulating BDNF and lactate, but not VEGF or IGF1, following aerobic exercise in both young controls and older adults. Further investigation into the mechanisms that contribute to these changes and the relevance to additional fluid and imaging brain health biomarkers in this cohort is ongoing.