Seniors are at increased risk of dehydration because their brains fail to effectively gauge how much water their bodies need, new research suggests.

Researchers at Australia's Howard Florey Institute and the University of Texas have identified a key region in the brain that governs water requirements.

'Scheduled drinking may be a strategy to reduce the risk of dehydration in older people.'— Report in the Proceedings of the National Academy of Sciences

Called the mid cingulate cortex, this section of the brain doesn't work properly in elderly people, according to a study published Tuesday in the Proceedings of the National Academy of Sciences.

When scientists gave two groups of participants — one aged 21 to 30 and the other 65 to 74 — salty water intravenously to induce thirst, they found that the older group consumed half as much water as the younger group.

"Using PET imaging, we found in the older people, the mid cingulate cortex was 'turned off' much earlier by drinking small volumes," researcher Dr. Michael Farrell said in a release. "This discovery helps explain why the elderly can become easily dehydrated."

The researchers say the findings help explain why so many older people die in mass heat waves.

"The apparent failure of central processes contributing to satiation has important public health implications for older people in hot environments or undertaking exercise," the report says. "Scheduled drinking may be a strategy to reduce the risk of dehydration in older people."

Dehydration symptoms, brought on when the body doesn't receive enough water to carry out its functions, include headache, fatigue and hallucinations. Prolonged dehydration can lead to death.