Cognitive Effects of Repeated Acute Exposure to Very High Altitude Among Altitude-Experienced Workers at 5050 m

Abstract

<b><i>Background:</i></b> We investigated altitude effects on different cognitive domains among perennial shift-workers at the Atacama Large Millimeter/submillimeter Array Observatory (5050 m), Chile. <b><i>Materials and Methods:</i></b> Twenty healthy male workers were recruited and assigned to either a moderate-altitude first (<i>MAF</i> group, <i>Test 1</i>: 2900 m and <i>Test 2</i>: 5050 m) or to a high-altitude first (<i>HAF</i> group, <i>Test 1</i>: 5050 m and <i>Test 2</i>: 2900 m). <i>Test 1</i> was conducted at the beginning and <i>Test 2</i> at the end of the shift-work week. Processing speed (RTI, reaction time), attention (AST, attention-switching task, and RVP, rapid visual processing), and executive function (OTS, One Touch Stockings of Cambridge) were assessed. <b><i>Results:</i></b> Of the three cognitive domains assessed, only processing speed showed altitude-at-test group interaction (RTI median five choice reaction time: <i>F</i>_{1, 17} = 6.980, [Formula: see text] = 0.291, <i>p</i> = 0.017). With acclimatization, there was a decrease in AST reaction latency mean (<i>t</i>₁₇ = -2.155, <i>d</i>_z<i> =</i> 1.086, <i>p</i> = 0.046), an increase in RVP accuracy (<i>t</i>₁₇ = 2.733, <i>d</i>_z<i> =</i> 1.398, <i>p</i> = 0.014), and a decrease in OTS mean latency first choice (<i>t</i>₁₇ = -2.375, <i>d</i>_z<i> =</i> 1.211, <i>p</i> = 0.03). Decreased variability in cognitive function was observed in AST reaction latency standard deviation (<i>t</i>₁₇ = -2.524, <i>d</i>_z<i> =</i> 1.282, <i>p</i> = 0.022) and in RVP response latency standard deviation (<i>t</i>₁₇ = -2.35, <i>d</i>_z<i> =</i> 1.177, <i>p</i> = 0.03) with acclimatization. At 5050 m of elevation, SpO₂ was positively correlated with executive function in the <i>MAF</i> group (OTS problems solved on first choice: <i>r</i>₍₅₎ = 0.839, <i>p</i> = 0.018) and negatively correlated with executive function latency standard deviations in the <i>HAF</i> group (OTS latency to first choice standard deviation: <i>r</i>₍₁₀₎ = -0.618, <i>p</i> = 0.032). <b><i>Conclusions:</i></b> Our findings highlight the importance of acclimatization and improvement of blood oxygen level, even among high altitude-experienced workers, to optimize performance of cognitively demanding work and reduce high altitude-associated health risks.