Single dose of alcohol modifies brain, study finds

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According to a new study, a single administration of alcohol permanently alters the morphology of neurons, reducing the rewarding effect of alcohol, suggesting that an alcohol addiction can begin to form as early as the first drink.

The study, published in Proceedings of the National Academy of Sciences, was led by Henrike Scholz, PhD, of the Institute for Zoology at the University of Cologne in Cologne, Germany. Scholz and her team, researchers from the University of Mannheim-Heidelberg and the University of Cologne sought to better understand the mechanisms behind the transition from sporadic drinking to chronic alcohol abuse in the brain.

“We set out to discover ethanol-dependent molecular changes. These, in turn, provide the basis for permanent cellular changes following a single acute ethanol intoxication,” said Scholz in a statement. “The effects of a single alcohol administration were examined at the molecular, cellular, and behavioral levels.”

The team administered a single dose of alcohol into fruit flies and mouse models and analyzed the effects on their behavior as well as their brain chemistry. Researchers found that the ethanol led to changes in mitochondrial dynamics and the structure of synapses in neurons. They found that the movement of mitochondria was impaired and the chemical balance between certain synapses was disturbed in the cells treated with ethanol. These changes remained permanent in both the flies and the mice. They were also associated with increased alcohol consumption and alcohol relapse later in life.

“It is remarkable that the cellular processes contributing to such complex reward behavior are conserved across species, suggesting a similar role in humans,” said Scholz. “It could be a possible general cellular process essential for learning and memory.”

According to the study’s authors, these results suggest that a single intoxication experience can lead to increased alcohol consumption as well as alcohol relapse later in life.

“These mechanisms may even be relevant to the observation in humans that the first alcohol intoxication at an early age is a critical risk factor for later alcohol intoxication and the development of alcohol addiction,” said Scholz. “This means that identifying lasting ethanol-dependent changes is an important first step in understanding how acute drinking can turn into chronic alcohol abuse.”