Deterioration of Cognitive Function During Cold Water Immersion is not Changed Following Repeated Exposure

Abstract

Acute cold exposure results in impaired cognitive function by diverting attention away from the primary task and reducing vigilance. Repeated exposure to cold stress induces physiological changes such as decreased skin temperature and a delayed onset of shivering in an effort to reduce heat loss and conserve energy during subsequent cold exposures. It is unclear if repeated exposure to cold attenuates the decrease in cognitive function typically seen during acute cold exposure. PURPOSE:To determine if cognitive function during acute cold exposure is changed following repeated immersions in cold water. METHODS: Eight healthy volunteers (age: 25.9 ± 6.4 years, height: 172.7 ± 6.3 cm, weight: 74.9 ± 11.4 kg) completed seven 90-minute cold water immersions in 10°C water. Subjects completed the psychomotor vigilance task (PVT) during the 1st, 4th, and 7th cold water immersion at several time points (pre, 5 min, 30 min, 60 min, 90 min). Core temperature, heart rate, skin temperature (Tsk), thermal sensation, and skin blood flow were collected during each heat trial. RESULTS: Significantly reduced skin temperature and a delayed onset of shivering were observed during the 7th cold water immersion when compared with the 1st, suggesting that acclimation to cold occurred. Reaction time (RT) (pre=263±7 msec, 5 min=268±12 msec, 30 min=278±10 msec, 60 min=294±7 msec, 90 min=291±8 msec; p<0.001) and variability of RT (VRT) (pre=40±6 msec, 5 min=43±5 msec, 30 min=46±4 msec, 60 min=51±3 msec, 90 min=49±4 msec; p<0.03) worsened during the initial cold exposure. In comparison, RT (pre=265±11 msec, 5 min=285±15 msec, 30 min=285±12 msec, 60 min=293±10 msec, 90 min=289±9 msec; p=0.75) and VRT (pre=43±5 msec, 5 min=44±5 msec, 30 min=44±3 msec, 60 min=50±4 msec, 90 min=47±4 msec; p=0.72) during the 7th cold water immersion were not different than the 1st cold water immersion. CONCLUSIONS: Although impairment in RT and VRT was observed on both the first and final immersions,these findings suggest that repeated immersions in cold water over 7 days do not attenuate the decline in cognitive function typically seen during acute cold stress.