Stress really does cause you to drink more

Periods of stress causes changes in the brain's chemical makeup which can encourage an increase in drinking by altering the reward system.

It changes what the body thinks it needs to survive, so stressed drinkers keep coming back for more.

Signals in the brain released by stress involve similar neurological pathways as those stimulated through addictive substances.

These misfiring neurons then causes changes in the brain's reward centre prompting excessive drinking.

But a better understanding the brain chemistry involved in stress and increased alcohol consumption could help people suffering from conditions such as post-traumatic stress disorder (PTSD).

The team from the University of Pennsylvania found rats exposed to stress voluntarily drank more alcohol compared to those not put under the same stresses.

Professor Dr John Dani chair of Neuroscience in the Perelman School of Medicine said: "The stressed rats drank significantly more than controls, and the increase was maintained for several weeks.

"The stress response evolved to protect us, but addictive drugs use those mechanisms and trick our brains to keep us coming back for more."

Rats were exposed to an acute stress for one hour, and then 15 hours later, researchers measured the amount of sugar water laced with ethanol that the mice drank.

The most interesting finding, the researchers say, is that after the stress, the reward circuitry looked normal at first glance when they examined the rodents' neurons.

However, if the circuits were strongly used, in this case via consumption of ethanol, alterations to neurons were noticeable and the dopamine response to alcohol was blunted.

The change in neuron physiology means that a specific set of neurons that are normally inhibitory flip and become excitatory.

This flip alters the rats' response to ethanol, making them consume more and more.

Professor Dani said: "We gave the rats a chemical to restore the stress-altered circuitry to normal, which in turn corrected the firing of the dopamine neurons.

"This line of research has implications for people with PTSD who have an increased risk for over-use of alcohol and drugs."

The team is now talking with other researchers to study compounds that potentially normalise the firing of neurons in the brain's reward system to help control the over-consumption of alcohol.

The study was published in Neuron.