1051 Brain Lactate Concentrations After Adolescent Concussion Are Associated with Sleep Efficiency

Abstract Introduction Lactate, a metabolic byproduct of neuronal activity, is cleared during sleep and considered a surrogate marker of glymphatic system activity. Following a concussion, brain lactate levels may rise because of increased demand for energy to restore cellular homeostasis. Clearance of lactate is increased during sleep, and as such is considered a surrogate marker of glymphatic system activity. Sleep may be disrupted following concussion, and poor sleep after concussion is associated with greater symptomatology and longer recovery, potentially due to altered glymphatic clearance. Whether post-concussion sleep efficiency is related to lactate concentrations is unknown. The purpose of our study was to evaluate the association between sleep efficiency and brain lactate in adolescents with concussion. Methods Using magnetic resonance spectroscopy (MRSpect) we assessed brain lactate concentration in the anterior cingulate gyrus (ACG) and posterior cingulate gyrus (PCG) in adolescents within 21 days of concussion. Scans were performed at 3T (Skyra, Siemens, Erlangen, Germany) using PRESS localization: TR=2000, TE=30ms, voxel size=20x20x20mm3, number of averages=128. Sleep efficiency was self-reported using the Pittsburgh Sleep Quality Index (PSQI) from date of injury through date of assessment and calculated as the average time asleep divided by the average time in bed (%). Separate linear regression models were constructed to determine the independent associations between sleep efficiency and lactate concentrations in the ACG and PCG, while controlling for biological sex. Results 27 adolescents with a concussion (15.8±1.27 years; 51% female; 11.8±4.19 days since injury) were included in analysis. After concussion, mean sleep efficiency was 88.2±12.8%, and mean lactate concentrations in the ACG and PCG were 0.74±0.24 mmol and 0.81±0.31mmol, respectively. After controlling for biological sex, worse (lower) sleep efficiency was associated with significantly higher lactate concentrations in the ACG (β= -20.71 p=0.05, 95%CI:-41.7-0.33), but no association was observed in the PCG (β=-3.17, p=0.71, 95%CI:-21.0-14.68). Conclusion Our results suggest that higher lactate concentrations may be associated with worse sleep efficiency, and may reflect poor glymphatic system function. Higher lactate levels may be part of an adaptive response to the brain’s increased energy demands following concussion. Support (if any) Funding sources- Tai Foundation, Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01HD108133)