Hydration and Cognitive Function

In 2019, researchers in Cangzhou, China, had 12 healthy young men go without water for 36 hours and then take tests to evaluate their cognitive abilities and mood. After that, they were given a liter and a half of water to drink and were retested an hour later.

When dehydrated, the participants experienced low energy levels and decreased self-esteem. They also did poorly on tests of memory and attention compared to when they had been given water.

A study the following year found similar results. Sixty-four college students were randomized to four groups. They all fasted overnight and took cognitive and mood assessments in the morning. Then, each group was given a different amount of water, ranging from half a liter to none, and was retested.

Those who drank the most water had less anger, fatigue, and overall mood disturbance than those who consumed the least (or none). The group that drank half a liter also showed significant improvement in working memory compared to their performance before drinking.

The participants in these studies experienced temporary cognitive decline when dehydrated, but there’s evidence that chronic dehydration can cause long-term neurological harm.

In 2018, researchers analyzed the hydration levels of 1,091 patients (by testing their urine) in an Alzheimer’s Evaluation Unit. They found that patients with cognitive decline or depression had higher levels of dehydration than those without these issues. Dehydration was linked to a greater risk of developing dementia, particularly Alzheimer’s disease and vascular dementia.

(Excerpt from The Food Revolution Network)