A study on rats has shown a drug commonly used to treat cognitive decline in patients with dementia also reverses the neurological damage caused by bouts of excessive drinking.

While there's still a lot to be learned about the negative effects of excess alcohol on adolescent brains, the drug could provide a reprieve from the hangovers of our misspent youth.

Donepezil is a pharmaceutical usually prescribed to reduce the confusion and memory loss caused by conditions such as Alzheimer's disease.

Exactly how it manages this isn't clear, but it is known to stop an enzyme called cholinesterase from producing a certain class of neurotransmitter in the brain.

Studies on adolescent intermittent ethanol exposure (AIE, or teen binge drinking to you and me) have suggested getting drunk several nights a week reduces those enzymes in certain areas of the adolescent brain.

What's more, it's an effect that could last well into adulthood.

A team of US researchers have put two and two together to discover donepezil might also be useful in undoing the nerve damage caused by AIE.

"Clinical studies are starting to show that adolescents who drink early and consistently across the college years have some deficits in learning and memory," says the study's senior author Scott Swartzwelder from Duke University.

"It's not a sledgehammer – it's not knocking their memory out completely – but there are demonstrable, if subtle, effects on their cognitive function."

There's no shortage of willing test subjects researchers could call on inside university campuses to sink shots three to four times a week in the name of science, even if it did end in an autopsy.

Thanks to a little thing called 'ethics committees', they were forced to use rats instead. Not quite as informative as human models, but at least they didn't have to arrange for designated drivers.

For just over two weeks, a bunch of 30-day-old rats either got moderately sloshed on ethanol every other day or so, or stayed nicely hydrated on distilled water.

They then had a break from all that partying for a further 20 days before being divided into two groups, each made of a mix of binge-drinking and teetotalling rats.

One half was then treated with donepezil for four days, the other given plain water, before their brains were analysed.

Adult rats that were frequently exposed to moderate levels of alcohol as 'teens' had fewer branches called dendritic spines emerging from their neurons.

"Any change in the density of spines on dendrites tells you those cells are processing information differently than they should be, and whether that processing goes up or down can be a problem," says Swartzwelder.

That wasn't the case in the alcohol-dosed rats treated with donepezil, whose dendritic spines seemed just fine.

On further digging, the researchers found a gene called Fmr1 was involved. Changes to this gene have been implicated in a range of mental health conditions, from Parkinson's disease to autism and various other forms of learning difficulty.

Its products usually play a key role in communication between neurons, so finding the gene's expression was also being impacted here is perhaps no surprise.

Donezepil didn't just reverse the structural damage to the nerve's branches; it undid the effects of alcohol on regulation of Fmr1.

Given teenagers have been drinking themselves silly since humans first found booze in yeast-infected fruit juice, you might think we'd know more about the effects of AIE.

Not so.

"Studies in humans of the long-term effects of drinking during adolescence are just beginning to emerge," says Swartzwelder.

"But the data we do have indicate negative cognitive effects, and this puts us one step closer to one day being able to reverse those."

We could also just tell teenagers not to binge drink. Given what little we do know about the brain damage it causes, not to mention that 16% of drinkers engage in binge drinking, it has the potential to be a massive health problem.

We shouldn't rely on medicine coming to the rescue, of course. But it's good to know somebody is thinking about the effects.

This research was published in Alcoholism: Clinical and Experimental Research.