Recently I was visiting friends in another part of the country. Also visiting were a pair of elderly twins, who were evidencing a great deal of confusion resembling symptoms of early dementia. In the process of observing them, they appeared to be drinking less than one glass of water a day (besides whatever they got from their food) and there was no known contraindication to their reducing fluid intake). We began encouraging them to drink more water. It was humorous (almost) to put a glass of water in front of each of them and hear them say they were not thirsty and did not need water. Knowing that thirst perception does tend to diminish with age, we eventually got them on board by just sitting down and drinking water with them. Within a day or two it was amazing to note their confusion disappearing. They had more physical and mental energy and their sense of humor was returning. Studies have shown that dehydration is lethal for brain function because the brain (nearly three-quarters fluid) uses water for its ‘thinking’ functions as well as for energy. Fortunately, becoming more hydrated through regular water intake appears able to reverse some symptoms of ‘senile dementia’ (as it was once called).