Alcohol is among the most commonly abused substances and men are almost twice as likely as women to develop alcoholism but there have been no clear reasons for this difference. 

A new study in Biological Psychiatry says that it may be biological and that dopamine is an important factor.  Dopamine is a catecholamine, molecules that serve as hormones and neurotransmitters,  and is a precursor of adrenaline.   Dopamine has multiple functions in the brain but the researchers considered it important in their research on a biology of alcoholism because of its pleasurable effects when it is released by rewarding experiences, such as sex or drugs.

The researchers from Columbia and Yale studied male and female college-age social drinkers in a laboratory test of alcohol consumption. After consuming an alcoholic or non-alcoholic drink, each participant underwent a specialized positron emission tomography (PET) scan, an imaging technique that can measure the amount of alcohol-induced dopamine release.

Despite similar consumptions of alcohol, the men had greater dopamine release than women. This increase was found in the ventral striatum, an area in the brain strongly associated with pleasure, reinforcement and addiction formation.

"In men, increased dopamine release also had a stronger association with subjective positive effects of alcohol intoxication," explained Dr. Nina Urban, corresponding author for this study. "This may contribute to the initial reinforcing properties of alcohol and the risk for habit formation."

Dr. Anissa Abi-Dargham, senior author on the project, said, "another important observation from this study is the decline in alcohol-induced dopamine release with repeated heavy drinking episodes. This may be one of the hallmarks of developing tolerance or transitioning into habit."

They say their findings indicate that the ability of alcohol to stimulate dopamine release may play an important and complex role in its rewarding effects and abuse liability in humans. This identification of an in vivo neurochemical mechanism that could help explain the sex difference in alcoholism is an exciting step forward in alcoholism research.

Citation: Nina B.L. Urban, Lawrence S. Kegeles, Mark Slifstein, Xiaoyan Xu, Diana Martinez, Ehab Sakr, Felipe Castillo, Tiffany Moadel, Stephanie S. O'Malley, John H. Krystal, Anissa Abi-Dargham, 'Sex Differences in Striatal Dopamine Release in Young Adults After Oral Alcohol Challenge: A Positron Emission Tomography Imaging Study With [11C]Raclopride', Biological Psychiatry, Volume 68, Issue 8, 15 October 2010, Pages 689-696 doi:10.1016/j.biopsych.2010.06.005