Researchers in the US say they have pinpointed a cell in the brain that encourages people to continue drinking.
They believe that blocking this cell could stop a person's urge to drink.
Experts said the findings could be used to develop medication to help alcoholics to stop drinking.
Scientists at the Ernest Gallo Clinic and Research Centre in San Francisco found that a signalling molecule in a region of the brain called the nucleus accumbens may contribute to alcohol craving.
It is well known that alcohol and other addictive substances activate this region of the brain and instil craving by activating a chemical called dopamine.
But the US scientists found that alcohol can also trigger another chemical called adenosine.
Together these chemicals send out signals to the brain, which maintain the urge to continue to drink alcohol.
Target
The findings, which follow tests on rats, are published in the journal Cell.
One of the authors, Dr Ivan Diamond, professor of neurology at University of California San Francisco and director of the EGCRC, said: "It enables a substance taken into the body - alcohol - to team up with the normal, ongoing dopamine process to cause an exaggerated response to alcohol."
He added: "It provides a novel target for new medications to prevent or reduce excessive drinking."
That view was shared by Dr Raynard Kington, acting director of the US National Institute on Alcohol Abuse and Alcoholism.
He said: "The report fast-forwards efforts to understand the precise brain mechanisms involved in alcohol-seeking behaviour.
"Extending this work in animal and human studies may fast-forward the development of medications to impede alcohol-seeking behaviour and prevent relapse in dependent drinkers."