Neurologists are warning that dehydration in winter poses a significant, often overlooked, risk to brain health. Reduced thirst signals in colder weather, combined with fluid loss from dry air and heating, can lead to thicker blood, reduced blood flow to the brain, and increased risk of stroke. Experts note that symptoms can be subtle and mistaken for seasonal fatigue, making seniors particularly vulnerable. Replacing lost fluids is crucial to prevent these neurological and cardiovascular strains.