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Suh et al. 2020

Cellular dehydration acutely degrades mood mainly in women: a counterbalanced, crossover trial

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Abstract

Background

Mild to moderate dehydration adversely affects mood and cognitive function. Common methods for inducing dehydration introduce confounding factors, thus it is unclear how each type of dehydration independently affects mood.

Objectives

To examine the acute effect of cellular dehydration induced by hypertonic saline infusion on mood.

Methods

Using a counter-balanced, crossover design, fourty-nine healthy adults (55% female, age: 39±8 y, BMI: 27.3±4.2 kg∙m-2) were infused intravenously with 3% hyperosmotic saline (HYPER) to induce cellular dehydration or 0.9% isotonic saline (ISO) for 2 h (0.1 ml∙kg-1∙min-1) as a control. The same volume of saline was infused in each trial to avoid fluid volume differences between trials. Blood samples were collected every 30-min to assess various biomarkers. Mood was assessed with the Profile of Mood State (POMS) questionnaire pre- and post-intervention. Thirst was assessed with a visual analog scale.

Results

Plasma osmolality increased from 285±3 mmol∙kg-1 to 305±4 mmol∙kg-1 in HYPER (P<0.05) and was unchanged in ISO (P>0.05). Total mood disturbance assessed by the POMS increased from 10.3±0.9 to 16.6±1.7 in HYPER (P<0.05), but not in ISO (P>0.05). Among POMS subcategories, confusion-bewilderment, depression-dejection and fatigue-inertia were increased in HYPER compared to ISO (P<0.05). When TMD responses in the HYPER trial were stratified by sex, the increase was significant in females (pre: 9.9±1.1, post: 18.3±2.4; P<0.001) but not in males (pre: 10.7±1.5, post: 14.5±2.2; P>0.05). Fatigue-inertia was also elevated post HYPER only in females (P<0.05). However, alertness decreased in men and women post-HYPER. Following the 2-h infusion, thirst and copeptin, a surrogate for vasopressin, was also greater in females than in males (21.3±2.0, 14.1±1.4 pmol·L-1; P<0.05) during HYPER.

Conclusion

Cellular dehydration acutely degraded mood state mainly in women. The mechanisms underlying sex differences remain to be determined but may be related to elevated thirst and vasopressin, assessed by copeptin.

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A word from our expert: Dr Tiphaine Vanhaecke, Health & Hydration Scientist, Danone Research France:

Many previous studies have explored mood changes in response to dehydration and have shown greater mood disturbances in females. But until today there was no data suggesting an underling mechanism for why women may be sensitive to dehydration-induced mood changes. This proof-of-concept study is the first to reveal a possible mechanism: women experienced greater elevation of copeptin as well as great mood disturbance. Might copeptin (vasopressin) be a key player in dehydration-related mood disturbance?