Acute supplementation of beta-hydroxybutyrate increases visual cortical excitability in humans: a combined EEG and MRS study

Increasing plasma levels of ketone bodies via supplementation or dieting has been repeatedly used to ameliorate neurological symptoms and enhance cognitive performance. Here we aim to gain insight into the underlying mechanisms by characterizing the acute effects on visual cortical function of a single dose β-hydroxybutyrate (βHB) supplementation. Young human volunteers were orally administered a βHB ester; we used EEG to assess cortical excitability and responsivity to visual stimulation, and Magnetic Resonance Spectroscopy to quantify glutamate and GABA+ concentrations in the occipital cortex. βHB supplementation increased the amplitude of Visual Evoked Potentials and enhanced the resting-state EEG alpha rhythm. These electrophysiological changes were paralleled by a neurometabolic change in the occipital cortex, where glutamate (but not GABA+) concentration increased. The glutamate increase was correlated with the increased Visual Evoked Potential amplitude. This suggests that acute βHB supplementation increases the excitability of the brain cortex, as assessed neurometabolically and electrophysiologically.