Meet acetaldehyde, the neurotransmitter that messes our brains on alcohol

Scientists recently uncovered new insights into how alcohol disrupts the brain's ability to adapt and learn. A study published in the journal Science Advances found that chronic alcohol exposure alters the activity patterns of cholinergic interneurons (CIN) in the brain, negatively affecting learning processes.

Cholinergic interneurons release acetylcholine, an important neurotransmitter, and play a key role in the striatum of the brain, influencing learning and reward-based motivation. "CIN act as filters, controlling the stimuli that activate these neurons," stated Jun Wang, head of the research laboratory at Texas A&M University College of Medicine, according to Gazeta.ru.

Using technologies such as optogenetics and fiber photometry, researchers studied how different phases of CIN activity influence behavior. Optogenetics allows scientists to control cellular activity using light, while fiber photometry is used to monitor the release of acetylcholine in real time. The study found that normally, CIN operate on a "burst-pause" principle—a rapid burst of activity is followed by a pause necessary for adaptation and learning new behavior. However, in animals subjected to chronic alcohol exposure, the "burst-pause" pattern is disrupted. Pauses become shorter and less pronounced, complicating important cognitive processes such as reversal learning—the ability to replace old behavior patterns with new ones.

These findings clarify the neurobiological mechanisms by which alcohol abuse affects the neural circuits responsible for concentration, attention, and memory. Alcohol abuse disrupts key neurobiological mechanisms necessary for adaptation and learning, according to OK Diario.

The impacts of alcohol on the brain extend beyond learning impairments. According to Dr. Richard Restak, excessive alcohol consumption affects memory and cognitive functions. Restak warns that alcohol not only affects memory but also interferes with essential cognitive functions such as judgment, decision-making, and learning ability.

Alcohol slows down cellular processes in the brain, especially signal transmission and communication between cells. This slowdown can lead to decreased reaction time and difficulties in motor coordination and logical thinking, according to Die Welt. Processes in mitochondria, the "energy factories" of cells, also slow down due to alcohol consumption, exacerbating fatigue and weakness.

Martin Morgenthaler, the chief physician at the Neurology Clinic at Westpfalz Clinic in Kaiserslautern, explains that alcohol affects the brain rapidly. "The alcohol you drink reaches the brain within six minutes, and it takes many hours for alcohol to be broken down in the brain after consumption," he said, according to Die Zeit. Morgenthaler notes that alcohol has both depressant and activating effects in different brain regions, which confuses the brain. "It's basically like pressing the gas and brake at the same time. The whole balance that has to prevail gets completely mixed up," he stated.

This interplay leads to perceptions of dizziness and impaired situational assessment. The euphoric state induced by alcohol can lead to a level of intoxication that a person may want to experience repeatedly. "We are a bit less inhibited because neurotransmitters like endorphins, dopamine, and serotonin are released," explained Morgenthaler, leading to a temporary feeling of euphoria.

However, the consequences of alcohol consumption often manifest the next day. One common result is the dreaded hangover. One of the causes of a hangover is the formation of acetaldehyde during the breakdown of alcohol. Acetaldehyde alters the body's own neurotransmitters, leading to the formation of free oxygen radicals, which cause headaches, according to T-Online. Additionally, every alcoholic drink contains methanol, and during its breakdown, formaldehyde and acetic acid are produced, contributing to hangover symptoms.

Dehydration is another factor. "Another factor is dehydration," reminds Morgenthaler, according to Die Zeit. Alcohol increases the frequency of urination, similar to coffee, leading to more frequent toilet visits and further dehydration.

Alcohol also impacts sleep quality. While alcohol is initially sleep-promoting, this effect reverses during the night, leading to interrupted and fragmented sleep. Morgenthaler explains that the frontal lobe of the brain remains active during alcohol-induced sleep, contributing to negative dreams.

In severe cases, excessive alcohol consumption can lead to blackouts. "Medically speaking, a blackout is an amnesia for things I am currently experiencing," said Morgenthaler, according to Die Zeit. During a blackout, the transmission from short-term to long-term memory no longer functions, and in extreme cases, a person may lose memory of the entire night due to alcohol consumption. The risk of blackouts increases the faster and the more alcohol is consumed, and is higher if different alcoholic beverages are consumed one after another or if alcohol is combined with other drugs.

Chronic excessive alcohol consumption can have long-term consequences on brain health. Alcohol damages peripheral nerves, causing alcoholic neuropathy, according to VnExpress. Symptoms include numbness, pain, or a tingling sensation in the hands and feet, muscle weakness, loss of coordination, and increased susceptibility to injury.

Excessive alcohol consumption is also linked to an increased risk of developing mental health disorders. People who drink excessively are more likely to suffer from anxiety, depression, and other psychological disorders, according to OK Diario. Alcohol can be a triggering or accelerating factor for cognitive decline and diseases like dementia.

This article was written in collaboration with generative AI company Alchemiq