0106 The Effects of Caffeine on Blood Pressure and Cognitive Performance in Hypoxic Conditions on the Slopes of Mt. Everest

Introduction

140 million people live above 2,400m worldwide. High altitude (HA) exposure can lead to sleep disruption, impaired cognitive performance, acute mountain sickness (AMS), elevated blood pressure (BP) and an increase in cardiovascular events in healthy people. Because caffeine can also increase BP, caffeine might need to be avoided at HA. Caffeine is the most widely used drug in the world but has yet to be studied extensively in hypoxic conditions. Therefore, the aim of the current study was to examine the effects of caffeine on cardiovascular variables and cognitive function at HA.

Methods

We conducted a non-randomized, single-blind, mixed model design at 4,300m on Mt. Everest. Thirty-three trekkers (nine females), aged 29.5±10.4 (mean±SD), ingested the study drug (placebo or 200 mg of caffeine) 1.5 hours after awakening. To control for withdrawal effects of caffeine, participants that self-reported consuming less than 47 mg of caffeine per day received the placebo while those that consumed more than that received caffeine. Cognitive function was tested using the Stroop task before and after the pill administration. BP was measured by a trained clinician using auscultatory method prior to and 30, 60 and 90 min after the pill administration.

Results

Caffeine improved cognitive performance when compared to the pretreatment measurement but was worse in the caffeine group prior to the pill administration when compared to the pretreatment placebo group. Additionally, caffeine did not have any major effect on BP when compared to pretreatment measures or the placebo group.

Conclusion

Caffeine does not seem to have an additive effect on increasing BP with HA. Additionally, because cognitive performance was worse in the chronic caffeine users prior to the pill administration, caffeine users might be more dependent on caffeine to perform optimally at HA. Based off of these data, caffeine seems to be a safe and beneficial drug at HA.

Support

NIH BUILD EXITO, University of Alaska Faculty Development Grant