As little as one drink can alter memory, study shows

Alcohol “hijacks” the brain and “changes how memories are formed” at a molecular level, causing drinkers to develop cravings that could lead to addiction, new research has found.

A group of scientists is exploring alcohol’s affect on memory formation at a molecular level

By studying fruit flies, whose reward and avoidance memories are “much the same” as those in humans, a group of scientists at Brown University in the US found that just a few alcoholic drinks change how memories are formed.

“One of the things I want to understand is why drugs of abuse can produce really rewarding memories when they’re actually neurotoxins,” said Karla Kaun, assistant professor of neuroscience at Brown University and senior author on the paper.

“All drugs of abuse – alcohol, opiates, cocaine, methamphetamine – have adverse side effects. They make people nauseous or they give people hangovers, so why do we find them so rewarding? Why do we remember the good things about them and not the bad?

“My team is trying to understand on a molecular level what drugs of abuse are doing to memories and why they’re causing cravings.”

Alcohol, the team discovered, “hijacks” a conserved memory pathway in the brain and changes which versions of genes are made, forming the cravings that fuel addiction.

Researchers found that one of the proteins responsible for the flies’ preference for alcohol is Notch, described as the first “domino” in a signalling pathway involved in embryo and brain development in all animals, including humans.

This “domino” protein affects a gene called the dopamine-2-like receptor, which makes a protein on neurons that recognises dopamine, the “feel-good” neurotransmitter.

“The dopamine-2-like receptor is known to be involved in encoding whether a memory is pleasing or aversive,” said postdoctoral researcher Emily Petruccelli. Alcohol hijacks this conserved memory pathway to form cravings.

Kaun added: “We think these results are highly likely to translate to other forms of addiction, but nobody has investigated that.” The team is therefore carrying out a similar study to examine how opiates may affect the same conserved molecular pathways.

Kaun is working with John McGeary, assistant professor of psychiatry and human behaviour at Brown, to look at DNA samples from patients with alcohol abuse disorders to see if they have genetic polymorphisms in any of the craving-related genes discovered in flies.

“If this works the same way in humans, one glass of wine is enough to activate the pathway, but it returns to normal within an hour,” Kaun said. “After three glasses, with an hour break in between, the pathway doesn’t return to normal after 24 hours. We think this persistence is likely what is changing the gene expression in memory circuits.

“Just something to keep in mind the next time you split a bottle of wine with a friend or spouse.”