Page last updated: May 2017
Gender dimorphism of brain reward system volumes in alcoholism

Previous research has indicated that the brain's reward network is smaller in alcoholic men compared to nonalcoholic men, but little is known about the volumes of reward regions in alcoholic women.

The brain's reward system is a group of structures that reinforce beneficial experiences, are involved in memory and complex decision-making and have been implicated in the development of substance use disorders. Differences exist between the psychological and behavioural profiles of women and men with alcoholism; women tend to have higher levels of anxiety, while men are more likely to exhibit anti-social characteristics. A collaborative study between researchers at Massachusetts General Hospital (MGH) and Boston University School of Medicine (BUSM) therefore investigated whether the alcoholism-associated reward system differences previously observed in men would also be seen in women.

The study enrolled 60 participants - 30 women and 30 men - with histories of long-term alcoholism who were currently abstinent and an equivalent group of nonalcoholic volunteers. Participants completed detailed medical histories and neuropsychological assessments and MRI brain scans were performed.

The results replicated the findings of previous studies. The average size of the reward region structures of alcoholic men was found to be 4.1% smaller than those of nonalcoholic men, but the average sizes of the same structures were 4.4% larger in alcoholic than in nonalcoholic women. The researchers state that the current study cannot determine whether these differences preceded or resulted from the development of alcoholism, but factors such as the duration and intensity of drinking appeared to reinforce these gender-specific effects.

The authors conclude that there is a significant gender interaction for the association between alcoholism and total reward network volumes, with ALC men having smaller reward volumes than NC men and ALC women having larger reward volumes than NC women. A negative association was also found between the length of sobriety and the size of the fluid-filled ventricles in the center of the brain. Among participants with alcoholism - both women and men - each year of sobriety was associated with a 1.8% decrease in the size of the ventricles, suggesting recovery from the damaging effects of alcoholism on the brain.

Source: Gender dimorphism of brain reward system volumes in alcoholism. Kayle S. Sawyer, Marlene Oscar-Berman, Olivier J. Barthelemy, George M. Papadimitriou, Gordon J. Harris, Nikos Makris. Psychiatry Research: Neuroimaging, 2017; 263: 15 DOI: 10.1016/j. pscychresns.2017.03.001.

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