Abstract

YOUNG, Hayley A.  and  BENTON, David. The use of moderated mediated analysis to study the influence of hypo-hydration on working memory. Nutr. Hosp. [online]. 2016, vol.33, suppl.3, pp.71-75. ISSN 1699-5198.  https://dx.doi.org/10.20960/nh.320.

Introduction: To date, dehydration has been typically reported to influence 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 fluid intake are likely to be influential. 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: firstly, is drinking influential?; 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 ^oC 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 efficiency 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 influenced cognitive functioning although there were individual differences in the response. The parameters that influence an adverse response to hypo-hydration need to be established to allow giving appropriate advice.

Keywords : Hypo-hydration; Moderated mediation analysis; Water; Working memory.

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