Drunken behavior is caused by alcohol breakdown products produced in the BRAIN and not the liver

Alcohol rises to your head and triggers drunken behavior through the breakdown of chemicals produced in the brain, a new study reveals.

The finding turns previous theories that it was linked to the liver upside down, and scientists believe it is key to fighting binge drinking and alcoholism.

Researchers from the National Institute on Alcohol Abuse and Alcoholism tested the impact of alcohol on chemicals in human brain and mouse samples.

They found that alcohol metabolism is regulated “directly in the brain,” as it breaks down beer, wine, or spirits and causes a range of behavioral side effects.

Enzymes in the brain produce a chemical when alcohol is broken down and the chemical disrupts pathways that lead to drunken behavior.

The team found that when the enzyme is removed, the chemical is not created – even with the same alcohol consumption – and that drunken behavior does not occur.

“It suggests the possibility of new targets to change the effects – and possibly treat alcohol use disorders,” said lead author Dr. Li Zhang.

The study sheds new light on why people can get tipsy after just one or two drinks, leading to unsteadiness, slurred speech and slower reaction times.

Dr. Zhang said alcohol suppresses human brain function and affects behavior, but little is known about the neurological processes that control it.

The possibility of alcohol metabolism in the brain has been a controversial topic within the field of alcohol research for decades, but has never been confirmed.

The behavioral effects of alcohol are already well known to be caused by metabolites made when the body breaks down beer, wine or spirits.

One of those metabolites, acetate, is produced by an enzyme called ALDH2 – which is abundant in the liver – but new tests by the US team show it’s also in the brain.

Specifically in astrocytes, also known as the ’tiles’ of the central nervous system, found in the cerebellum, a region of the brain that controls balance and coordination.

When ALDH2 was removed from the cells, the laboratory rodents became immune to motor disorders caused by alcohol consumption.

They performed just as well as their peers on a rotating cylinder – or rotarod – that measures their balance and coordination skills.

Dr. Zhang said there is a long-standing idea that alcohol-related behavior largely stems from the alcohol metabolism in the liver, transported across the blood-brain barrier.

“Our data presented here directly challenges this idea,” she said.

They found that drinking alcohol fuels the metabolite and GABA – a neurotransmitter that calms the nerves and causes drowsiness.

Thoughts, speech, and movements slow down because different parts of the brain cannot coordinate movement, speech, and brain function as effectively.

That’s why we slurp our words, don’t pick up on social cues, can’t make decisions, and get clumsy when we’re drunk.

Dr. Zhang explained that despite being under the influence of alcohol, there was a marked improvement in function when ALDH2 was removed from astrocytes.

“In contrast, removing ALDH2 in the liver did not affect the levels of acetate or GABA in the brain,” the author explained.

“These findings suggest that acetate produced in the brain and in the liver differ in their ability to affect motor skills.”

The study published in Nature Metabolism opens the door to better regulation of the effects of drink on behavior.

It could lead to improved therapies for alcoholism and binge drinking – and other conditions that impair balance and coordination, including stroke, Parkinson’s disease and multiple sclerosis.

Dr. Zhang said, “Astrocytic ALDH2 is a prime target not only for alcohol use disorders, but for other neurological conditions as well.”