Many of us are all too familiar with the changes that come with aging – sagging skin, loss of muscle mass and bone density, more frequent memory lapses, the list goes on. But of all these changes, perhaps one of the least familiar nevertheless has an enormous impact on healthspan and longevity: the decline in our ability to stay sufficiently hydrated. …
Aging impairs fluid intake and output regulation
Elderly adults have long been known to have blunted thirst responses to dehydration. A classic 1984 study compared perceived thirst in response to water deprivation in healthy men aged 67-75 and aged 20-31 and showed that the older group reported less thirst and consumed less water following the deprivation period, despite exhibiting greater objective measures of dehydration. Similar results have since been observed in response to other thirst-inducing stimuli, such as hypertonic saline infusion or heat stress, but the precise mechanisms underlying this age-associated defect in thirst responses have yet to be fully elucidated.
Further elevation of dehydration risk arises from an age-associated decline in urine concentrating ability. While young adults decrease urine output in response to water deprivation, previous work has demonstrated that this reduction in excretion is somewhat diminished in individuals aged 40-59 and almost completely absent in those aged 60-79. One reason for this is a decrease in the kidneys’ ability to respond to antidiuretic hormone (also known as vasopressin) – a hormone responsible for stimulating water reabsorption from urine, among other roles in maintaining fluid balance. (Vasopressin is also inhibited by alcohol, which is why alcohol consumption paradoxically produces dehydration.)
Low muscle mass exacerbates the problem
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Preventing dehydration – and its consequences – as we age
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