|If you want to stay smart, you should join hands w/ water!|
In today's SuppVersity article, I will now take a step back, away from the musclehead's only interest and peek at other health aspects that are influenced by the hydration status not just of your muscles, but of your whole body.
In one of the most recent papers on this issue, Natalie A. Masento and her colleagues from the University of Reading reviewed the surprisingly profound effect of dehydration on cognition and mood, of which Masento et al. write that it is "particularly relevant for those with poor fluid regulation, such as the elderly and children" (Masento. 2014).
"With evidence to suggest that individuals are routinely at a risk of mild dehydration day to day (Greenleaf. 1965), particularly vulnerable populations such as children and older adults, there has been an increased interest in studying whether additional water consumption might benefit cognitive performance. The small collection of published water intervention studies involving either young adults or school children report consistent positive effects of water intervention on particular cognitive abilities" (Masento. 2014)If you take a look at the overview, the researchers compiled (it's too long and eventually repetitive to post it here), you will find studies everything from self-reported fatigue, tiredness and headaches to objectively measured declines in cognitive performance, eye-hand coordination, word recognition, visual attention and - as mentioned in the previously cited article physical performance markers, such as grip strength.
How come? I mean, why does dehydration have such a profound impact?
The above, probably is the question that's preying on your mind right now and I have to admit, I have - just like the researchers from the University of Reading - no conclusive, water-tight *pun intended* answer to that question.
"Despite the expansion of this research area, we still do not have a clear understanding as to how acute water intervention may influence mental performance and its associated neural activity. Researchers have suggested psychological mechanisms related to limited attentional resources during thirst. However, evidence has also highlighted the importance of physiological mechanisms, with findings that the expectancy of water alone does not influence cognitive performance." (Masento. 2014)Hitherto proposed mechanisms include references to the Global Workspace Model (Baars. 1993) and being distracted by the often subconscious thought "Where do I find water".
|Gray matter activation clusters in dehydration (Streibürger. 2012).|
- shrinkage of total brain volume shrinkage (Streitbürger. 2012; Kempton. 2011) and
- over-recruitment of specific brain areas during cognitively demanding tasks,
Luckily, these changes can be reversed by the provision of water in minutes, as long as the subjects are only mildly dehydrated. In view of the
"lack of data related to baseline hydration states of individuals and no further published work using imaging techniques to examine hydration state" (Masento. 2014)We do yet once more have to acknowledge that "we know that we know nothing" or, put differently, that these proposed mechanisms are merely speculative.
Potential causes of dehydration: It's not just working out in the heat or simply forgetting to drink (very common in the elderly), there is a multitude of other things that promote dehydration and here are a couple of examples: ✋Low sodium + chloride (can't store water), ✋high calcium, magnesium, zinc, chromium intake, ✋ extreme high sodium or potassium intake, ✋low phosphor intake; ✋high vitamin D, pantothenic acid (B5), pyridoxine (B6) intake; ✋low adrenal output; ✋high protein intakes (esp. when protein is abused as energy source); ✋laxatives, diuretics or other meds or supps -- One thing, however, does not cause dehydration: ☕ Coffee!Another physiological mechanism that has been suggested is the albeit age-dependent reaction of the central nervous system in response to the ingestion of significant (500ml) amounts of water, of wich May & Jordan found that it causes
- a significant drop in heart rate and an increase in vasodilation in young adults (May. 2011), and the opposite effects, i.e.
- a significant increase in blood pressure in the healthy old subjects in a 2002 study by Schroeder et al. (Schroeder. 2002)
If you think about this hypothesis, i.e. the beneficial effects of water-induced increases, and the detrimental effects of reductions in glucose and oxygen availability in the brain and other organs that would occur, even upon mild dehydration, it seems perfectly logical, a mechanism similar to that has after all been proposed to account for the improved cognitive function due to physical exercise (Kashihara. 2009).
- Baars, Bernard J. "How does a serial, integrated and very limited stream of consciousness emerge from a nervous system that is mostly unconscious, distributed, parallel and of." Experimental and theoretical studies of consciousness 174 (1993): 282.
- Greenleaf, John E., and Frederick Sargent. "Voluntary dehydration in man." Journal of Applied Physiology 20.4 (1965): 719-724.
- Kempton, Matthew J., et al. "Dehydration affects brain structure and function in healthy adolescents." Human brain mapping 32.1 (2011): 71-79.
- Masento et al. "Effects of hydration status on cognitive performance and mood". British Journal of Nutrition (2014) [ahead of print].
- Ribeiro, Alex S., et al. "Resistance training promotes increase in intracellular hydration in men and women." European Journal of Sport Science ahead-of-print (2014): 1-8.
- Schroeder, Christoph, et al. "Water drinking acutely improves orthostatic tolerance in healthy subjects." Circulation 106.22 (2002): 2806-2811.
- Streitbürger, Daniel-Paolo, et al. "Investigating structural brain changes of dehydration using voxel-based morphometry." PloS one 7.8 (2012): e44195.
- Wakefield, Bonnie, et al. "Monitoring hydration status in elderly veterans." Western Journal of Nursing Research 24.2 (2002): 132-142.