Acute hypoxia impairs posterior cerebral bioenergetics and memory in man
Soichi Ando, Hayato Tsukamoto, Benjamin S. Stacey, Takuro Washio, Thomas S. Owens, Thomas A. Calverley, Lewis Fall, Christopher J. Marley, Angelo Iannetelli, Takeshi Hashimoto, Shigehiko Ogoh, Damian M. Bailey
Abstract
Abstract Hypoxia has the potential to impair cognitive function; however, it is still uncertain which cognitive domains are adversely affected. We examined the effects of acute hypoxia (∼7 h) on central executive (Go/No‐Go) and non‐executive (memory) tasks and the extent to which impairment was potentially related to regional cerebral blood flow and oxygen delivery (CDO 2 ). Twelve male participants performed cognitive tasks following 0, 2, 4 and 6 h of passive exposure to both normoxia and hypoxia (12% O 2 ), in a randomized block cross‐over single‐blinded design. Middle cerebral artery (MCA) and posterior cerebral artery (PCA) blood velocities and corresponding CDO 2 were determined using bilateral transcranial Doppler ultrasound. In hypoxia, MCA DO 2 was reduced during the Go/No‐Go task ( P = 0.010 vs. normoxia, main effect), and PCA DO 2 was attenuated during memorization ( P = 0.005 vs. normoxia) and recall components ( P = 0.002 vs. normoxia) in the memory task. The accuracy of the memory task was also impaired in hypoxia ( P = 0.049 vs. normoxia). In contrast, hypoxia failed to alter reaction time ( P = 0.19 vs. normoxia) or accuracy ( P = 0.20 vs. normoxia) during the Go/No‐Go task, indicating that selective attention and response inhibition were preserved. Hypoxia did not affect cerebral blood flow or corresponding CDO 2 responses to cognitive activity ( P > 0.05 vs. normoxia). Collectively, these findings highlight the differential sensitivity of cognitive domains, with memory being selectively vulnerable in hypoxia.