Brain glucose metabolism changes acutely following exercise and tracks with the systemic lactate response

Background Aerobic exercise may positively affect brain health, although relationships with cognitive change are mixed. This likely is due to individual differences in the systemic physiological response to exercise. However, the acute effects of exercise on brain metabolism and biomarker responses are not well characterized in older adults or cognitively impaired individuals. Method The Acute Exercise Response on Brain Imaging and Cognition (AEROBIC) study is a randomized, controlled trial (NCT04299308). We enrolled older adults (60+years) who were cognitively healthy (n = 30) or cognitively impaired (n = 30) based on a clinical exam (telephone CDR). Study visits included a cardiorespiratory fitness test, Fluorodeoxyglucose [18F] PET (FDG‐PET) scans with timecourse blood draws during both rest and exercise, and resting MRI. Participants were randomized to both intensity (moderate; 45‐55% heart rate reserve (HRR) or higher (65‐75% HRR)) and PET visit order. Lactate and various exercise‐related biomarkers were measured. Each session concluded with cognitive testing (NIH Toolbox). Change in whole‐grey matter cerebral glucose metabolism from rest to exercise was registered as the primary outcome. We used general linear modeling to test for a primary effect of Condition (exercise vs. rest), as well as the effects of intensity and cognitive diagnosis, on the change in FDG‐PET SUVR and lactate AUC. Result FDG‐PET SUVR differed significantly between exercise (1.045 ± .082) and rest (.985 ± .077) across the entire cohort (Diff = ‐.060, t(58) = 13.8, p