The body is mainly water, and I believe maintaining hydration is an important component of optimal health. I wrote most recently about this back in February (see here). This blog piece details some of the major roles that water has in the body (e.g. as a temperature regulator, carrier and building material). In practice, I have noticed that dehydration has the capacity to provoke many adverse symptoms, perhaps the most common of which is lethargy – particularly mental lethargy. It’s based on clinical observation, but I generally believe that maintaining hydration is important for fluid thinking.

I was therefore interested to read a recent study in which the affects of dehydration on brain function was tested [1]. The study essentially induced dehydration in individuals by having them exercise in a warm environment. Their brain function was assessed using what is known as functional magnetic resonance imaging. Part of this test involved subjecting individuals to an assessment known as the blood-oxygen-level-dependent (BOLD) response, which essentially measures the increase in resources (oxygen and nutrients) diverted to a part of the brain once activated.

The subjects, after being made dehydrated, were assessed with a problem solving test. Compared to a better hydrated state, those who were dehydrated has a great BOLD response. What this essentially suggests is that a dehydrated brain requires more resources (has to work harder) to get the same result. The authors of this study concluded that “Given the limited availability of brain metabolic resources, these findings suggest that prolonged states of reduced water intake may adversely impact executive functions such as planning and visuo-spatial processing.”

Here, it seems we have at least some subjective evidence which suggests that hydration is important for optimal brain function. I advise individuals to drink enough water to keep their urine pale yellow in colour right throughout the day. Should urine stray into darker tones, I suggest upping water intake. I have found in practice, that just this one simple measure usually increases energy levels (including mental energy) within half an hour or so.

This study was actually performed in adolescents. As I was reminded yesterday by a friend, exam time is looming for many adolescents. One simple thing that may help their revision and exam performance is for them to simply add water.

References:

1. Kempton KJ, et al. Dehydration affects brain structure and function in healthy adolescents. Human Brain Mapping 24 March 2010 [epub ahead of print]