Effects of skin and mild core cooling on cognitive function in cold air in men

Abstract

This study tested the effects of skin and core cooling on cognitive function in 0°C cold air. Ten males completed a randomized, repeated measures study consisting of four environmental conditions: (i) 30 min of exposure to 22°C thermoneutral air (TN), (ii) 15 min to 0°C cold air which cooled skin temperature to ~27°C (CS), (iii) 0°C cold air exposure causing mild core cooling of ∆-0.3°C from baseline (C-0.3°C) and (iv) 0°C cold air exposure causing mild core cooling of ∆-0.8°C from baseline (C-0.8°C). Cognitive function (reaction time [ms] and errors made [#]) were tested using a simple reaction test, a two-six item working memory capacity task, and vertical flanker task to assess executive function. There were no condition effects (all p > 0.05) for number of errors made on any task. There were no significant differences in reaction time relative to TN for the vertical flanker and item working memory capacity task. However, simple reaction time was slower in C-0.3°C (297 ± 33 ms) and C-0.8°C (296 ± 41 ms) compared to CS (267 ± 26 ms) but not TN (274 ± 38). Despite small changes in simple reaction time (~30 ms), executive function and working memory was maintained in 0°C cold air with up to ∆-0.8°C reduction in core temperature.

Keywords: cognition; cold stress; core cooling; executive attention; skin cooling.

FIGURE 1

Thermal responses for core rectal temperature (panel A), whole‐body mean skin temperature (panel B), forearm temperature (panel C), and hand temperature (panel D) (n = 10 males). Data were analyzed using a 2 Time × 4 Condition repeated measure ANOVA. All data demonstrated a condition, time, and interaction effect (all p < 0.05). Pairwise comparisons can be interpreted as a = difference between TN and CS, b = difference between TN and C‐0.3°C, c = difference between TN and C‐0.8°C, d = difference between CS and C‐0.3°C, e = difference between CS and C‐0.8°C, f = difference between C‐0.3°C and C‐0.8°C. TN = thermoneutral, CS = Cold Skin/Shell, HYPO‐0.5°C = mild core cooling (hypothermia) of ∆‐0.5°C from baseline, HYPO‐1.0°C = mild core cooling (hypothermia) of ∆‐1.0°C from baseline.

FIGURE 2

Heart rate (panel A) and metabolic heat production (panel B) responses (n = 10 males). Data were analyzed using a 2 Time × 4 Condition repeated measure ANOVA. All data are presented as mean ± SD. All data demonstrated a condition, time, and interaction effect (all p < 0.05). Pairwise comparisons can be interpreted as a = difference between TN and CS, b = difference between TN and C‐0.3°C, c = difference between TN and C‐0.8°C, d = difference between CS and C‐0.3°C, e = difference between CS and C‐0.8°C, f = difference between C‐0.3°C and C‐0.8°C. TN = thermoneutral, CS = Cold Skin/Shell, HYPO‐0.5°C = mild core cooling (hypothermia) of ∆‐0.5°C from baseline, HYPO‐1.0°C = mild core cooling (hypothermia) of ∆‐1.0°C from baseline.