Alcoholism linked to hyper-active brain in people

Alcoholics release abnormally high levels of the reward chemical dopamine in their brains when they drink, a new study suggests.
The brains of people who are vulnerable to alcoholism react very differently to alcohol than the brains of people who are not vulnerable, according to a new study by Professor Marco Leyton from McGill University.
Compared to people at low risk for alcohol-use problems, those at high risk showed a greater dopamine response in a brain pathway that increases desire for rewards.
These findings could help shed light on why some people are more at risk of suffering from alcoholism and could mark an important step toward the development of treatment options.

"There is accumulating evidence that there are multiple pathways to alcoholism, each associated with a distinct set of personality traits and neurobiological features," said Leyton.
"These individual differences likely influence a wide range of behaviours, 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," leyton said.

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.

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," said Leyton.
"This large response might energise reward-seeking behaviours 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," said Leyton.
"Although preliminary, the results are compelling," said Leyton.
"A much larger body of research has identified a role for dopamine in reward-seeking behaviours 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," said Leyton.
The study was published in the journal Alcoholism: Clinical & Experimental Research.