2007, Piran, Slovenia

Cognitive and Psycophysiological Function
THE EFFECT OF PASSIVE HEATING AND HEAD COOLING
ON COGNITIVE PERFORMANCE
Shona E. Simmons 1, 2 , Brian K. Saxby 3 . Francis P. McGlone 2 and David A. Jones 1
1 University of Birmingham, Birmingham, United Kingdom. 2 Unilever R&D, Wirral,
United Kingdom. 3 Cognitive Drug Research, Goring-on-Thames, United Kingdom
Contact person: Shona.Simmons@Unilever.com
INTRODUCTION
This study investigated the relationship between feelings of heat-related fatigue and
cognitive performance and whether cooling the skin when hot can result in
improvements in cognitive performance. Reports of the effect of heat on cognitive
performance are varied, with a number reporting decrements, some reporting little or
no effect while others have shown improvements upon initial exposure to heat.
Generally the role of skin cooling, specifically head cooling, is considered beneficial
in reducing thermal strain and thermal discomfort both at rest and during exercise in
hot environments. Reductions in thermal strain with head cooling have been reported
as a consequence of reductions in heart rate, however very little research has
described other cardiovascular responses to head cooling during passive heating.
Although there have been previous studies of the effects of increasing body
temperature on perception and cognitive performance none have systematically
investigated the interaction of core and skin temperature. In the present study we
hypothesised that skin temperature, rather than core temperature induces feelings of
heat-related fatigue and that cooling the skin of the head and neck would modulate
these feelings. It was further hypothesised that decrements in cognitive performance
would occur with an increase in body temperature of ≥1°C and cooling the skin of the
head and neck would modulate these decrements in cognitive performance. The
present study also investigated whether cooling the head and neck would reduce
cardiovascular strain induced by passive heating.
METHODS
Ten (6 male) non acclimated, right handed, healthy volunteers (male age 33.2 ± 6.8
years, BMI 24.5 ± 2.8 and female age 26.5 ± 5.2 years, BMI 21.2 ± 2.4) gave written
consent to participate following local ethics approval. Cognitive performance was
assessed using a 15-minute battery of tasks (CFT’s) from the Cognitive Drug
Research computerised cognitive assessment system. The tasks were presented on a
laptop computer with responses made using a two-button YES/NO response box and
included Simple Reaction Time (SRT), Choice Reaction Time (CRT), Digit Vigilance
(DV), and Rapid Visual Information Processing (RVIP). In addition to the analysis of
the individual measures, two composite scores based on previous factor analysis were
used to further characterise the data these were Power of Attention and Continuity of
Attention (Wesnes et al., 2000). Motor performance was assessed using a 1-minute
Morse Tapping task and a series of Bond-Lader Mood Scales (1974) were used to
assess self-perception of calmness, contentment and alertness.
Cognitive function was assessed in three conditions; subjects initially sat at 25°C,
50% relative humidity (RH) with low skin and low core temperature (LSLC), ambient
temperature was then increased to 45°C, 50% RH where, after 30-minutes, skin
temperature was high and core temperature remained low (HSLC); thereafter subjects
113