Effect of Acute Ingestion of a Ketone Monoester on Psychomotor Vigilance During Acute Severe Hypoxia Exposure.

INTRODUCTION: Transient ketosis produced by the acute ingestion of exogenous ketone supplements has been demonstrated to attenuate declines in executive function during acute exposure to hypoxia. Investigation of whether similar effects are observed in other domains of cognitive performance is warranted. MATERIALS AND METHODS: Sustained attention and vigilance were assessed in n = 16 male participants who undertook the psychomotor vigilance test while wearing a reduced oxygen breathing device in normoxia (15 minutes; 0 m; 20.9%O2), and followed 30 minutes later by hypoxia (15 minutes; simulated altitude of 6,096 m, 9.7%O2). This protocol was performed on two separate occasions in a double-blind crossover design during which either the (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (R-BD R-βHB) ketone monoester (KME; 650 mg/kg body mass) or a taste-matched placebo (PLA) was ingested. RESULTS: A rapid and sustained (>3 mM; P < .001) increase in blood R-βHB concentration was observed and was accompanied by ∼20 mg/dL (P < .01) lower blood glucose concentration throughout KME compared to PLA. Heart rate was higher in hypoxia compared to normoxia for both KME [13.6 (6.7, 20.7) bpm; P < .01] and PLA [13.2 (9.2, 17.2) bpm; P < .001], but the change from normoxia to hypoxia was not different between conditions (P = .87). The hypoxia-induced decline in mean reaction time was attenuated (P = .002) with KME, which resulted in a faster mean reaction time [25.5 (10.7, 40.3) milliseconds] in hypoxia compared to PLA. No significant differences between KME and PLA were observed for the deleterious effect of hypoxia on other outcome measures from the psychomotor vigilance test. CONCLUSIONS: Acute ingestion of the R-BD R-βHB KME partially attenuated the decline in sustained attention and vigilance that occurred during acute exposure to severe hypoxia, and may support cognitive resilience under environmental stress.