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The independent influences of heat strain and dehydration upon cognition

Journal Article


Abstract


  • Purpose Many researchers have addressed the potential

    efects of hyperthermia and dehydration on cognition,

    often revealing contradictory outcomes. A possible reason

    for this inconsistency is that experiments may have been

    inadequately designed for such efects. In this study, the

    impact of hyperthermia, dehydration and their combination

    on cognition were evaluated in eight young males, after

    accounting for a range of experimental limitations.

    Methods Passive heating and thermal clamping at two

    mean body temperatures (36.5, 38.5°C) were performed

    under three hydration states (euhydrated, 3 and 5% dehydrated)

    to assess their efects on difculty-matched working

    memory and visual perception tasks, and on a difculty

    manipulated perceptual task. Data were analysed according

    to signal detection theory to isolate changes in response

    sensitivity, bias and speed.

    Results Neither moderate hyperthermia (P=0.141) nor

    dehydration (P>0.604) modifed response sensitivity, nor

    did they signifcantly interact (P>0.698). Therefore, the

    ability to distinguish correct from incorrect responses was

    unafected. Nevertheless, hyperthermia, but not dehydration

    (P=0.301), reduced the response bias (−0.08 versus

    2.2 [normothermia]; P=0.010) and reaction time (mean

    reduction 49  ms; P<0.001), eliciting more liberal and

    faster responses (P=0.010). Response bias was reduced for

    the memory relative to the perceptual task (P=0.037), and

    this efect was enhanced during hyperthermia (P=0.031).

    Conclusions These observations imply that, once potentially

    confounding infuences were controlled, moderate

    hyperthermia, signifcant dehydration and their combined

    efects had insufcient impact to impair cognition within

    the memory and perceptual domains tested. Nonetheless,

    moderate hyperthermia elicited more liberal and rapid

    responses.

Authors


  •   van den Heuvel, Anne (external author)
  •   Haberley, Benjamin (external author)
  •   Hoyle, David (external author)
  •   Taylor, Nigel A.S.. (external author)
  •   Croft, Rodney J.

Publication Date


  • 2017

Citation


  • van den Heuvel, A. M. J., Haberley, B. J., Hoyle, D. J. R., Taylor, N. A.S.. & Croft, R. J. (2017). The independent influences of heat strain and dehydration upon cognition. European Journal of Applied Physiology, 117 (5), 1025-1037.

Scopus Eid


  • 2-s2.0-85016041333

Number Of Pages


  • 12

Start Page


  • 1025

End Page


  • 1037

Volume


  • 117

Issue


  • 5

Place Of Publication


  • Germany

Abstract


  • Purpose Many researchers have addressed the potential

    efects of hyperthermia and dehydration on cognition,

    often revealing contradictory outcomes. A possible reason

    for this inconsistency is that experiments may have been

    inadequately designed for such efects. In this study, the

    impact of hyperthermia, dehydration and their combination

    on cognition were evaluated in eight young males, after

    accounting for a range of experimental limitations.

    Methods Passive heating and thermal clamping at two

    mean body temperatures (36.5, 38.5°C) were performed

    under three hydration states (euhydrated, 3 and 5% dehydrated)

    to assess their efects on difculty-matched working

    memory and visual perception tasks, and on a difculty

    manipulated perceptual task. Data were analysed according

    to signal detection theory to isolate changes in response

    sensitivity, bias and speed.

    Results Neither moderate hyperthermia (P=0.141) nor

    dehydration (P>0.604) modifed response sensitivity, nor

    did they signifcantly interact (P>0.698). Therefore, the

    ability to distinguish correct from incorrect responses was

    unafected. Nevertheless, hyperthermia, but not dehydration

    (P=0.301), reduced the response bias (−0.08 versus

    2.2 [normothermia]; P=0.010) and reaction time (mean

    reduction 49  ms; P<0.001), eliciting more liberal and

    faster responses (P=0.010). Response bias was reduced for

    the memory relative to the perceptual task (P=0.037), and

    this efect was enhanced during hyperthermia (P=0.031).

    Conclusions These observations imply that, once potentially

    confounding infuences were controlled, moderate

    hyperthermia, signifcant dehydration and their combined

    efects had insufcient impact to impair cognition within

    the memory and perceptual domains tested. Nonetheless,

    moderate hyperthermia elicited more liberal and rapid

    responses.

Authors


  •   van den Heuvel, Anne (external author)
  •   Haberley, Benjamin (external author)
  •   Hoyle, David (external author)
  •   Taylor, Nigel A.S.. (external author)
  •   Croft, Rodney J.

Publication Date


  • 2017

Citation


  • van den Heuvel, A. M. J., Haberley, B. J., Hoyle, D. J. R., Taylor, N. A.S.. & Croft, R. J. (2017). The independent influences of heat strain and dehydration upon cognition. European Journal of Applied Physiology, 117 (5), 1025-1037.

Scopus Eid


  • 2-s2.0-85016041333

Number Of Pages


  • 12

Start Page


  • 1025

End Page


  • 1037

Volume


  • 117

Issue


  • 5

Place Of Publication


  • Germany