What factor is known to increase the risk of dehydration in older adults?

The factor that is known to increase the risk of dehydration in older adults is decreased thirst perception. As individuals age, the body's physiological responses can change, including a reduction in the sensitivity of the thirst mechanism. This means that older adults may not feel thirsty even when their bodies need fluid, leading to a lower intake of water and fluids overall. Additionally, many older adults may not recognize the importance of hydration or may forget to drink fluids, compounding the risk of dehydration. This diminished response to thirst is significant, as adequate hydration is crucial for maintaining bodily functions, regulating body temperature, and preventing complications associated with dehydration, such as kidney issues or cognitive decline.

The other factors presented do not contribute to increased dehydration risk in the same way. For example, increased physical activity might lead to a higher fluid requirement, but it is not inherently linked to an increased dehydration risk if proper hydration practices are followed. Higher fluid intake is, of course, essential to prevent dehydration, while increased appetite does not directly relate to fluid needs.