Hyperthermia impairs the executive function using the Attention Network Test.

ABSTRACT

PURPOSE: The primary aim of this study was to examine the effect of passive hyperthermia on the human attention system using the Attention Network Test (ANT), which has been used in both healthy controls and patients. Using target contrasts between conditions within a Flanker paradigm, the ANT can isolate three essential networks in the attention system maintaining an alert state that is receptive to stimulus input and ready for responding; orienting, which involves selection of sensory input; and executive control, which monitors for and resolves conflict in responding or other aspects of cognitive processing. MATERIALS AND METHODS: The ANT was administered to 16 right-handed subjects in a heat stress condition (50°C, 40% relative humidity) and a control condition (20°C, 40% relative humidity), for 1 hour each. Reaction time (RT) and accuracy rate as well as mean body core temperature (T-core) and body weight loss were recorded. RESULTS: Compared to the control condition, T-cores significantly increased and body weight was not significantly reduced in the heat stress condition. Overall, there were non-significant group differences for RT and accuracy rate. Although significant changes in neither alerting nor orienting effects were modulated by the simulated hyperthermia, the executive control effect on RTs was significantly larger in the heat compared to the control condition. CONCLUSIONS: Passive hyperthermia impaired executive control function, whereas alerting and orienting effects were unaffected.