Mild dehydration affects mood

PainSci » bibliography » Armstrong et al 2012
updated Apr 13, 2023

Tags: random, hda, water, bad science, controversy, debunkery, scientific medicine

Three articles on PainSci cite Armstrong 2012: 1. The Complete Guide to Chronic Tension Headaches 2. Water Fever and the Fear of Chronic Dehydration 3. Why Drink Water After Massage?

PainSci commentary on Armstrong 2012: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

This research, funded in part by a giant corporation that sells bottled water, supposedly shows that surprising mild dehydration can make you a bit pissy and headachy.

The level of dehydration studied here is similar to what it takes to provoke thirst, and the effects on mood are presumably milder at the lower end of the range. So if the effect on mood is significant, we are probably also thirsty ... and if we’re not actually thirsty, the effect is probably pretty minor. That said, I might agree with the author’s conclusion that “increased emphasis on optimal hydration is warranted,” but I’m also guessing it’s not that big a deal, and I’m inclined to be rather cynical about it, because the conclusion is just so pitch-perfect for a study funded by a water bottling company.

Mood effects are not to be ignored, for sure, but they are also a lot less serious than the health effects that people tend to believe (mostly based on very successful fear-mongering by people selling ‘water cures’).

~ Paul Ingraham

original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

Limited information is available regarding the effects of mild dehydration on cognitive function. Therefore, mild dehydration was produced by intermittent moderate exercise without hyperthermia and its effects on cognitive function of women were investigated. Twenty-five females (age 23.0 ± 0.6 y) participated in three 8-h, placebo-controlled experiments involving a different hydration state each day: exercise-induced dehydration with no diuretic (DN), exercise-induced dehydration plus diuretic (DD; furosemide, 40 mg), and euhydration (EU). Cognitive performance, mood, and symptoms of dehydration were assessed during each experiment, 3 times at rest and during each of 3 exercise sessions. The DN and DD trials in which a volunteer attained a ≥1% level of dehydration were pooled and compared to that volunteer's equivalent EU trials. Mean dehydration achieved during these DN and DD trials was -1.36 ± 0.16% of body mass. Significant adverse effects of dehydration were present at rest and during exercise for vigor-activity, fatigue-inertia, and total mood disturbance scores of the Profile of Mood States and for task difficulty, concentration, and headache as assessed by questionnaire. Most aspects of cognitive performance were not affected by dehydration. Serum osmolality, a marker of hydration, was greater in the mean of the dehydrated trials in which a ≥1% level of dehydration was achieved (P = 0.006) compared to EU. In conclusion, degraded mood, increased perception of task difficulty, lower concentration, and headache symptoms resulted from 1.36% dehydration in females. Increased emphasis on optimal hydration is warranted, especially during and after moderate exercise.

original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

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