Influence of heat-stress induced dehydration on mental functions

Sharma, Vandana; Sridharan, K.; Pichan, G.; Panwar, Mamta

doi:10.1080/00140138608968315

Cited by 139 publications

(112 citation statements)

References 11 publications

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“…2) and previous findings: using the same paradigm, drinking prevented a decline in episodic memory and focussed attention (13). Yet the present report contrasts with previous reports in that working memory was not disrupted by a loss of 1-2% of body mass (4,(8)(9)(10) and that even a loss of more than 2% has only sometimes (4-8) been found to be disruptive.…”

Section: Discussioncontrasting

confidence: 57%

“…Although there are reports stating that a loss of body mass greater than 2% disrupts working memory (4,5), this finding has not always been replicated (6)(7)(8). Working memory has never been reported to be disrupted by a loss of 1-2% of body mass (4,(8)(9)(10). As such, if the use of moderated mediation can demonstrate that a small difference in hydration can be disruptive under some conditions, the value of this novel statistical approach would be demonstrated.…”

Section: Objectivesmentioning

confidence: 99%

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The use of moderated mediated analysis to study the influence of hypo-hydration on working memory

Young¹

2016

Nutr Hosp

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Introduction: To date, dehydration has been typically reported to infl uence psychological parameters when there has been at least a 2% loss of body mass, although there has been little examination of those going about their everyday lives, those who have lost less than 1% of body mass. In such situations factors such as the initial hydration status and individual differences in the response to a reduced fl uid intake are likely to be infl uential. Yet to study the complexity added by such additional variables novel methods of statistical analysis are required. Objectives: The present study describes the use of moderated mediation, an approach that asks various questions: fi rstly, is drinking infl uential?; secondly, does a mediator (e.g., thirst) sit between an independent and dependent variable?; and thirdly, does an effect only occur under certain conditions such as initial osmolality? Method: In the study, 118 subjects were exposed to 30 °C for four hours during which they half drank 300 ml water. The serial sevens test of working memory was performed before and at the end of the procedure. Results: A 0.6% loss of body mass reduced the effi ciency of working memory. Those who consumed water had better working memory; working memory was worse in participants who lost more body mass or became thirstier, but only in those with higher levels of baseline osmolality. Conclusions: Small variations in hydration status infl uenced cognitive functioning although there were individual differences in the response. The parameters that infl uence an adverse response to hypo-hydration need to be established to allow giving appropriate advice.

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Section: Discussioncontrasting

confidence: 57%

Section: Objectivesmentioning

confidence: 99%

The use of moderated mediated analysis to study the influence of hypo-hydration on working memory

Young¹

2016

Nutr Hosp

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“…Available studies have identified several domains of cognitive function that are affected by dehydration (Sharma et al, 1986;Gopinathan et al, 1988). Gopinathan et al (1988) examined changes in cognitive function in 11 healthy adult subjects under varying degrees of dehydration induced by a combination of water restriction and heat stress.…”

Section: Pathophysiologymentioning

confidence: 99%

Impaired cognitive function and mental performance in mild dehydration

2003

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Dehydration is a reliable predictor of impaired cognitive status. Objective data, using tests of cortical function, support the deterioration of mental performance in mildly dehydrated younger adults. Dehydration frequently results in delirium as a manifestation of cognitive dysfunction. Although, the occurrence of delirium suggests transient acute global cerebral dysfunction, cognitive impairment may not be completely reversible. Animal studies have identified neuronal mitochondrial damage and glutamate hypertransmission in dehydrated rats. Additional studies have identified an increase in cerebral nicotinamide adenine dinucleotide phosphate-diaphorase activity (nitric oxide synthase, NOS) with dehydration. Available evidence also implicates NOS as a neurotransmitter in long-term potentiation, rendering this a critical enzyme in facilitating learning and memory. With ageing, a reduction of NOS activity has been identified in the cortex and striatum of rats. The reduction of NOs synthase activity that occurs with ageing may blunt the rise that occurs with dehydration, and possibly interfere with memory processing and cognitive function. Dehydration has been shown to be a reliable predictor of increasing frailty, deteriorating mental performance and poor quality of life. Intervention models directed toward improving outcomes in dehydration must incorporate strategies to enhance prompt recognition of cognitive dysfunction.

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“…For instance, dehydration has well established negative effects on cognitive performance (see Edmonds, 2012, for a review). In adults, dehydration to a loss of more than 2% body weight, induced by heat exposure or exercise, results in poor performance on tasks assessing memory and psychomotor performance (Gopinathan, Pichan, & Sharma, 1988;Sharma, Sridharan, Pichan, & Panwar, 1986); although see Secher and Ritz (2012) for a discussion of methodological limitations. Subjective feelings of concentration and alertness are also negatively affected (Armstrong et al, 2012;Shirrefs, Merson, Fraser, & Archer, 2004;Szinnai, Schachinger, Arnaud, Linder, & Keller, 2005).…”

Section: Introductionmentioning

confidence: 99%

Water consumption, not expectancies about water consumption, affects cognitive performance in adults

et al. 2013

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Research has shown that water supplementation positively affects cognitive performance in children and adults. The present study considered whether this could be a result of expectancies that individuals have about the effects of water on cognition. Forty seven participants were recruited and told the study was examining the effects of repeated testing on cognitive performance. They were assigned either to a condition in which positive expectancies about the effects of drinking water were induced, or a control condition in which no expectancies were induced. Within these groups, approximately half were given a drink of water, while the remainder were not. Performance on a thirst scale, letter cancellation, digit span forwards and backwards and a simple reaction time task was assessed at baseline (before the drink) and 20 minutes and 40 minutes after water consumption. Effects of water, but not expectancy, were found on subjective thirst ratings and letter cancellation task performance, but not on digit span or reaction time. This suggests that water consumption effects on letter cancellation are due to the physiological effects of water, rather than expectancies about the effects of drinking water.

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Influence of heat-stress induced dehydration on mental functions

Cited by 139 publications

References 11 publications

The use of moderated mediated analysis to study the influence of hypo-hydration on working memory

The use of moderated mediated analysis to study the influence of hypo-hydration on working memory

Impaired cognitive function and mental performance in mild dehydration

Water consumption, not expectancies about water consumption, affects cognitive performance in adults

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