Which physiological age-related change is most responsible for dehydration in older adults?

• A. Taste buds are more sensitive, leading to decreased desire for liquids.
• B. Thirst decreases, contributing to less fluid intake.
• C. Increased glomerular filtration rate.
• D. Constriction of the esophagus prevents fluid metabolism.

Answer: (B)

The main concept here is that the thirst drive declines with age, so older adults often don’t feel thirsty even when their body needs fluids. The thirst mechanism, governed by the hypothalamus and osmoreceptors, becomes less responsive as people get older. This blunted signal leads to reduced fluid intake, which is a major driver of dehydration in the elderly.

Other options don’t fit this pattern. Taste changes in aging don’t typically increase the desire for liquids; in fact, taste perception can diminish, which doesn’t explain dehydration. Glomerular filtration rate generally decreases with age, not increases, so it wouldn’t account for dehydration by a higher filtration alone. Esophageal constriction isn’t a typical, widespread cause of dehydration from aging and isn’t about the body’s drive to drink. Focus on the reduced thirst sensation as the key factor explains why dehydration is common, even with available fluids.