A new research done by scientists from Georgia Institute of Technology (GIT) reports that dehydration can lead to swelling of parts of our brains, intensification of neural signals, and make it harder to perform simple, monotonous tasks.
Exercise physiologists at GIT worked with several volunteers to see how dehydration affected responses to a repetitive task- with the help of brain scans. The chosen volunteers were people who sweated a lot but weren’t hydrated enough. This loss of water led to volunteers not being able to perform the task properly.
The scans revealed that areas of brain also demonstrated some conspicuous changes. “We wanted to tease out whether exercise and heat stress alone have an impact on your cognitive function and study the effect of dehydration on top of that,” said Mindy Millard-Stafford, principal investigator of the study and a professor in Georgia Tech’s School of Biological Sciences. “We found a two-step decline.”
Millard-Stafford and Matt Wittbrodt, the study’s first author and a former graduate research assistant at Georgia Tech who is now a postdoctoral researcher at Emory University, published their study recently in the journal Physiological Reports.
While conducting the experiments. the reserach team observed that when volunteers exercised, sweated, but stayed hydrated, their ventricles- which are fluid filled spaces in the center of their brains- contracted. When volunteers exerted themselves but were dehydrated, the ventricles expanded. Functional magnetic resonance imaging (fMRI) helped reveal these differences.
“The structural changes were remarkably consistent across individuals,” added Millard-Stafford a past president of The American College of Sports Medicine. “But performance differences in the tasks could not be explained by changes in the size of those brain areas.”
The research team also noted that the dehydration caused changes in neural firing patterns. “The areas in the brain required for doing the task appeared to activate more intensely than before, and also, areas lit up that were not necessarily involved in completing the task,” said Wittbrodt. “We think the latter may be in response to the physiological state: the body signaling, ‘I’m dehydrated.”
Volunteers were asked to perform a monotonous task of punching a button every time a yellow squared button appeared on a monitor for 20 minutes straight. The task had been deliberately designed so. “It helped us to avoid the cognitive complexity behind elaborate tasks and strip cognition down to simple motor output,” Wittbrodt added. “It was designed to hit essential neural processing one would use to make straightforward, repetitive movements.”
Past studies have also suggested that this kind of task reflects the neural processing that is involved in real-life motor functions. Heat, strain, and fluid loss can make attention lapses during such monotonous lapses worse.