Cellular Dehydration Acutely Degrades Mood Mainly In Women: A Counterbalanced, Crossover Trial (Vol 125, Pg 240, 2020)

It is unclear if mild-to-moderate dehydration independently affects mood without confounders like heat exposure or exercise. This study examined the acute effect of cellular dehydration on mood. Forty-nine adults (55 % female, age 39 (sd 8) years) were assigned to counterbalanced, crossover trials. Intracellular dehydration was induced with 2-h (0 center dot 1 ml/kg per min) 3 % hypertonic saline (HYPER) infusion or 0 center dot 9 % isotonic saline (ISO) as a control. Plasma osmolality increased in HYPER (pre 285 (sd 3), post 305 (sd 4) mmol/kg; P < 0 center dot 05) but remained unchanged in ISO (pre 285 (sd 3), post 288 (sd 3) mmol/kg; P > 0 center dot 05). Mood was assessed with the short version of the Profile of Mood States Questionnaire (POMS). The POMS sub-scale (confusion-bewilderment, depression-dejection, fatigue-inertia) increased in HYPER compared with ISO (P < 0 center dot 05). Total mood disturbance score (TMD) assessed by POMS increased from 10 center dot 3 (sd 0 center dot 9) to 16 center dot 6 (sd 1 center dot 7) in HYPER (P < 0 center dot 01), but not in ISO (P > 0 center dot 05). When TMD was stratified by sex, the increase in the HYPER trial was significant in females (P < 0 center dot 01) but not in males (P > 0 center dot 05). Following infusion, thirst and copeptin (surrogate for vasopressin) were also higher in females than in males (21 center dot 3 (sd 2 center dot 0), 14 center dot 1 (sd 1 center dot 4) pmol/l; P < 0 center dot 01) during HYPER. In conclusion, cellular dehydration acutely degraded specific aspects of mood mainly in women. The mechanisms underlying sex differences may be related to elevated thirst and vasopressin.