Rhodiola crenulata extract supplement significantly attenuates hypoxia-reduced oxygen saturation and cognitive function

Introduction: Hypoxic exposure leads to impaired cognitive function that decreases the performance of pilots in multitasking operations. Rhodiola crenulata has demonstrated in vitro and in vivo antihypoxic properties. However, its effect on hypoxia-induced cognitive impairment remains unclear. We aimed to investigate the positive effects of Rhodiola on cognitive function.Methods: Thirty-nine healthy participants were recruited in the study. Each subject received either two capsules (627 mg/capsule) of Rhodiola crenulata extract (RCE) or a placebo 48 hours before performing the cognitive tasks (digit span tasks [DST]; Word-Colour Stroop Task [WCST], and Trail Making Tests [TMT]) under normoxic and hypoxic conditions. The blood oxygen saturation level (SpO(2)) was also monitored using a pulse oximeter. The Lake Louise AMS Symptom Score Questionnaire, as well as stress saliva markers, were measured. Each subject completed four sessions (normoxia, RCE, hypoxia, and hypoxia + RCE) in a randomised order under atmospheric pressure for 30 minutes.Results: Hypoxia significantly decreased SpO(2) levels (P < 0.05), short-term and working memory capacity (DST), cognitive flexibility, and selective attention (WCST) and executive functioning (TMT types A and B). However, RCE pretreatment significantly prevented hypoxia-induced reductions in SpO(2) levels, DST, WCST, and TMT. In addition, RCE attenuated the acute mountain sickness-like symptoms.Conclusions: RCE exerts a beneficial effect on hypoxia-induced cognitive impairment and might be a potential agent against hypoxic insult in the aviation environment.