Alcohol Hijacks How Brain Makes Memories—In Fruit Flies

Drinking alcohol hijacks the brain's pathways which form memories according to scientists researching the causes of addiction.

The study on flies published in the journal Neuron indicates even low doses of alcohol change how certain genes are expressed.

By providing a deeper understanding of how our bodies form cravings this research could one day form the basis of treatments for addicts, the team hopes.

Researchers investigating the causes of addiction conducted a study on fruit flies. Getty Images

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Anyone who has experienced a hangover can attest that substances like alcohol can trigger painful side effects in the body. So too do opiates, cocaine and methamphetamines - but users are still drawn to the sense of reward they produce. Scientists wanted to investigate this contradictory attraction at a molecular level.

Dr. Karla Kaun, senior author of the paper and assistant professor of neuroscience at Brown University, explained to Newsweek: "While you are drinking, you are forming memories for cues in your environment, like the feel of the glass or the bouquet of your wine, that become associated with the feeling of being intoxicated.

"Our study provides genetic and biochemical evidence that fairly low doses of alcohol can activate a highly conserved cell-signaling pathway in the brain, leading to changes in expression of genes important for learning and memory."

Memories for cues associated with addictive substances like alcohol last for a relatively long time, Kaun said, and can cause recovering addicts to relapse.

"This [the study] suggests that the genes being expressed in your reward circuits are changing while you are forming memories for the pharmacological properties of alcohol," she said.

Fruit flies were used in the study, Kaun explained, because the team needed to be precise in the way they manipulated genes so they could investigate brain circuits as the animals formed memories.

The way in which a fruit fly's brain forms memories are similar to humans, but in a scaled-down version of 100,000 neurons compared with 100 billion.To pinpoint the proteins associated with reward behaviors, the researchers trained the flies to find alcohol and switched on and off certain genes.

The data revealed alcohol activates a protein called Notch which is involved in how the brain functions.

"Our data suggest that alcohol-induced activation of the highly conserved Notch pathway and accompanying transcriptional responses in memory circuitry contribute to addiction," said Kaun.

However, the use of flies presents an obstacle in how closely the results resemble what happens in the human brain.

"We hope our work inspires other scientists to translate these findings to mammals in order to understand if the same mechanisms occur in our brains," she said.

Dr. Peter Giese, Professor of Neurobiology of Mental Health at King's College London, U.K., pointed out the study suggests the Notch signaling process underlies memory processes which result in long-lasting changes to gene transcription.

"Therefore, the study not only provides a model for understanding the persistence of drug addiction, it also identifies potential pharmacological targets for treating addiction," he said.

Giese told Newsweek: "I was impressed that alcohol exposure could induce such long-lasting changes in gene expression in a critical memory centre in fruit flies."

If this association is investigated further, the research could be used to confirm that addiction may be prevented by interfering with Notch signaling and its target transcriptional changes, said Giese.

As for the take-home message for members of the public concerned about how drinking impacts their brain, Giese said: "the reader should be mindful that drinking can cause addiction which is very likely due to activation of memory processes. So the alcohol hijacks brain processes that allow us to remember things for a very long time."

Earlier this year, the authors of a separate study found binge-drinking just once can disturb the gene that regulates sleep.

For the study published in the Journal of Neurochemistry, researchers at University of Missouri-Columbia allowed mice to binge-drink and assessed their sleep patterns.

Dr. Ivona Bialas, a senior lecturer at the Brighton and Sussex Medical School who was not involved in the study, told Newsweek at the time: "The results, if they can be replicated, are astounding. They highlight the huge impact even small amounts of alcohol have on sleep."