Flood of dopamine may fuel desire to drink

MCGILL (CAN) — A pathway in our brains that makes us crave reward goes into high gear when some people take a drink.

Compared to people at low risk for alcohol-use problems, those at high risk show a greater dopamine response in this brain pathway, researchers say.

The findings could help shed light on why some people are more at risk for alcoholism and could mark an important step toward better treatment options.

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“There is accumulating evidence that there are multiple pathways to alcoholism, each associated with a distinct set of personality traits and neurobiological features,” says Marco Leyton, a professor of psychiatry at McGill University.

“These individual differences likely influence a wide range of behaviors, both positive and problematic. Our study suggests that a tendency to experience a large dopamine response when drinking alcohol might contribute to one (or more) of these pathways.”

For the study published in the journal Alcoholism: Clinical & Experimental Research, researchers recruited 26 healthy social drinkers (18 men, 8 women), 18 to 30 years of age, from the Montreal area.

The higher-risk subjects were then identified based on personality traits and having a lower intoxication response to alcohol (they did not feel as drunk despite having drunk the same amount).

Finally, each participant underwent two positron emission tomography (PET) brain scan exams after drinking either juice or alcohol (about 3 drinks in 15 minutes).

“We found that people vulnerable to developing alcoholism experienced an unusually large brain dopamine response when they took a drink,” Leyton says.

“This large response might energize reward-seeking behaviors and counteract the sedative effects of alcohol. Conversely, people who experience minimal dopamine release when they drink might find the sedative effects of alcohol especially pronounced.

“Although preliminary, the results are compelling, a much larger body of research has identified a role for dopamine in reward-seeking behaviors in general. For example, in both laboratory animals and people, increased dopamine transmission seems to enhance the attractiveness of reward-related stimuli.

“This effect likely contributes to why having one drink increases the probability of getting a second one—the alcohol-induced dopamine response makes the second drink look all the more desirable. If some people are experiencing unusually large dopamine responses to alcohol, this might put them at risk.

“People with loved ones struggling with alcoholism often want to know two things: how did they develop this problem? And what can be done to help? Our study helps us answer the first question by furthering our understanding of the causes of addictions. This is an important step toward developing treatments and preventing the disorder in others.”

McGill University and the Canadian Institutes of Health Research funded the research.

Source: McGill University