Brains hardwired to stop us from overdrinking water

A new brain imaging study has found that our brains are hardwired to stop us from drinking more water than necessary.

The study led by the University Of Melbourne and the Florey Institute of Neuroscience and Mental Health, found a 'stop mechanism' that determined brain signals telling the individual to stop drinking water when no longer thirsty, and the brain effects of drinking more water than healthy.

Researcher Derek Denton from the university said that the study provided insight into the human instincts that determine survival behaviour and are also of medical importance.

Different areas of the brain involved in emotional decision-making were activated when people drank water after becoming thirsty and when study participants followed instructions to keep drinking when no longer thirsty, he said.

"The brain regions determining the signals to stop drinking have not previously been recognised in this context. It identifies an important component in regulation and this 'stop mechanism' may prevent complications from excessive water intake," he said.

Overdrinking can reduce the salt concentration of the blood that can result in the swelling of the brain, a potentially fatal condition called polydipsia, which has been found in some patients with schizophrenia and in some marathon runners.