We all had that one night when we drank much more than we were supposed to. Just to wake up with the worst hangover of all time. One day, I woke up hangover in my bed, not remembering all too well what happened the night before with spaghetti spilled on my crotch. Then, I called my friends to find out what the hell happened to me. He said that I told them I was going to start my own fight club and left the bar. Apparently, I walked home while heavily intoxicated. My house was almost 15 km away.

Alcohol is as old as civilization. People even worshiped wine and beer gods including the Maya (Acan, God of alcohol), the Greek (Dionysus, God of wine), the Romans (Bacchur, God of wine) and even the Egyptians (Nephthys, Goddess of beer). As you can see, alcohol had a big part in our history and still affecting our lives. In Russia alone, there are over 500,000 alcohol-related deaths each year.

Dionysus, God of wine (Source:flickr.com)

Alcohol is actually quite easy to make all you have to do is to squash grapes into juice. This can be done using a wine press or simply using your feet in a process called grape stomping. Yeast is then added to the juice and sealed in a jar. Yeasts convert the sugar in the grape juice into alcohol. Eventually, all the sugar is turned into alcohol and the yeasts die of starvation. Alcohol can also be made from corn, rice, wheat, and even rye.

Today, we will be talking about the science behind alcohol consumption but before we jump into it, here are some fun facts about alcohol.

  • In Ohio, it is illegal to get a fish drunk.
  • Alcohol kills one person every 10 seconds worldwide.
  • Alcohol is not digested, it gets immersed directly into the bloodstream.
  • Scientist Nikola Tesla drank whiskey every day because he thought it would make him live to 150 years old.
  • People with blue eyes have a greater alcohol tolerance.
  • Cenosillicaphobia is the fear of an empty glass.

Whether you liked it or not, alcohol beverages are a part of many cultures around the world and daily products for many, so it’s a good idea to know what alcohol does to our bodies on the short run and why people still love it despite its many harmful effects proven day after day by scientists…

Altering the brain’s chemistry:

After a couple of good drinks, there is always that feeling of a temporary relaxation and peace, what’s really happening in your brain?
You see the neurons communicate through chemical substances called neurotransmitters, we talk about excitatory neurotransmitters if the receiving neuron is fired up in the process and inhibitory neurotransmitters in the opposite scenario. Unfortunately, it’s not that simple because in reality, we cannot talk about neurotransmitters alone but rather the duo neurotransmitter/receptor. A good example is dopamine receptors, there are five types known by scientists, D1 dopaminergic receptors are one of them, they increase the activity in the limbic system and reward pathways giving you that feeling of euphoria (excitatory effect) while D2 dopaminergic receptors inhibit any extra electric activity, they are mainly found in the basal ganglia inside the brain and regulate the movements (inhibitory effect). Generally speaking, the neurotransmitters found in the brain can be classified either excitatory or inhibitory due to the dominance of one type of receptors. That being said, you should know that the main excitatory neurotransmitter in the brain is Glutamate and the main inhibitory neurotransmitter is GABA but others exist of course.
When ethanol reaches the neurons, it binds to glutamate receptors the NMDA receptors reducing the excitatory signals and at the same time it enhances the GABA pathways inhibiting even further the brain’s overall activity, as a result, you will get that feeling of indifference, relaxation, and tiredness.
It’s like locking up your brain, all your cognitive abilities are reduced, you think less, feel less and move less. One time, I had a couple of drinks with a friend of mine, he mentioned a random girl he saw on the streets that he liked very much, she sounded familiar, he said. strangely he kept repeating the same idea over and over with no purpose. You probably experience the same thing at a certain moment so why is that? The excessive inhibition done by alcohol explains it clearly, drunk people tend to stick to one idea all night long because their brain is so focused and relaxed, no interferences whatsoever. That’s why when I caught myself in a circle of negative overthinking, I will go for few drinks and usually, it works like magic!

What about feeling good and being honest?

Alcohol increases dopamine levels in the brain, the feel-good hormone, we don’t know exactly how it’s done but there’s a clear relationship between activating the reward system and alcohol consumption.
The reward system is composed of different brain regions responsible for survival instincts such as food intake, water consumption, sex etc… It’s among the first structures in mammals’ brains that served our ancestors thousands of years ago to stay alive. A direct action of alcohol on D1 receptors stimulation is very unlikely and few studies support this claim, an indirect action is more suitable to explain the interaction. The reward system is also responsible for building an addiction over time, other drugs such as cocaine are more potent than alcohol but the mechanisms are similar. So basically alcohol makes us feel good but how about telling the truth ? is it a myth or a fact?

Lie detector (Source: theatlantic.com)

Well a little bit of both I guess, the lying part of our brain is the prefrontal cortex, lying detectors compare the activity of this part to a normal activity to predict if somebody is lying or not. With the overall inhibition, the prefrontal cortex works less than usual no activity = no lying = telling the truth! Have you ever wonder why we lie in the first place? Well, it’s complex! It’s related to the thinking brain and developing an easier method to get things, what we know for sure is it’s related to emotions. The limbic system triggers the process of lying in the response of a negative feeling, fear, rejection, self-doubt etc.. Alcohol makes us feel free so we don’t find ourselves obliged to lie to anyone because we are in a good mood and really don’t give a fuck about any consequence for the moment. The myth about stimulating the truth center is wrong because there’s no truth center at all, we simply develop lying as an evolutionary process to ensure our survival, it’s a good thing alcohol exist after all!

But wait! Why can’t I walk normally?

When alcohol levels surpass 1.5g/l (This number is different from one person to another) the inhibition becomes so strong that you start losing control over your body.
Let’s say you want to move your feet, the motor cortex sends signals to a variety of nuclei inside your brain called the basal ganglia, like any other part of your brain, these nuclei use neurotransmitters to communicate between each other especially our beloved friend: Glutamate.
The basal ganglia have two different pathways for executing movements, the direct pathway for facilitating a wanted action and the indirect pathway for inhibiting random chaotic movements, we’re not going into details because the subject is so deep but think of them more like the Yin and Yang of nervous motor control.
With ethanol reaching serious high levels these pathways are affected and glutamate cannot function properly resulting in a temporary loss of motor control and you start swinging left and right!

Ok, that sounds fun! still, why do we get hangovers?

Hangovers are unpleasant collateral damages after a beautiful drinking night. The causes are multiple, we have managed to explain many of its aspects but not all of them. After ethanol enters the bloodstream, the liver starts converting it to acetaldehyde by the enzyme alcohol dehydrogenase. Acetaldehyde is very toxic and can cause serious symptoms of dizziness and vomiting, the higher its concentration, the worse a hangover!

(Source: Wikimedia)

Luckily, the liver converts it into acetic acid which is less toxic and easily removed from the body by the enzyme acetaldehyde dehydrogenase using a compound called glutathione. The downside of the process is its limitation, the liver doesn’t have enough glutathione to metabolize all the acetaldehyde leading to a progressive buildup as the night goes. In one hour, the liver has the potential to remove approximately the quantity of alcohol found in one beer, that’s nothing compared to alcohol contained in stronger beverages.
Ever heard about the Asian Flush? well, it’s a condition characterized by a really fast acetaldehyde buildup due to an abnormally fast activity if the enzyme acetaldehyde dehydrogenase. The skin becomes red as a result of acetaldehyde accumulation and the hangover occurs more often and it’s usually more severe, remember that the next time you have a drink with your Asian friend! Seriously be gentle :p

The toxins produced by alcohol metabolism alongside with other compounds found in the alcoholic beverages such as the congeners (substances produced during fermentation ) explain the vast majority of symptoms seen in hangovers, dizziness, nausea, vomiting etc.. but that’s not all!
It’s known that alcohol causes dehydration and that’s totally accurate, in fact, it inhibits the production of antidiuretic hormone (ADH) by the pituitary gland. ADH is a very important hormone that controls the quantity of water in the body and the osmolarity of the blood when you are thirsty, the levels of ADH increase dramatically and these molecules bind to specific receptors found in the collecting duct of kidney increasing water resorption as a result.

ADH effects (Source: cnx.org)

The water loss may interfere with electrolyte balance aggravating even further the symptoms of a hangover, although this is not always seen in most people, it can happen. Its also important to mention that alcohol can cause hypoglycemia aka low blood sugar levels, scientists believe that the strains put on the liver decrease the production of glycogen (long chains of glucose stocked in the liver and muscles) and thus decreasing blood sugar levels, hypoglycemia share a variety of symptoms with hangover which means that even a small hypoglycemia can worsen the symptoms a lot. All these factors combined contribute to the discomfort of a hangover but that doesn’t stop us from drinking anyway! Who doesn’t want a rush of dopamine from time to time?

References and for further readings:

Alcohol
Brain effects of alcohol
The dopamine system and alcohol dependence
Basal ganglia
The direct pathway
The indirect pathway
Alcohol hangover: a critical review of explanatory factors.
Alcohol Metabolism
Overall view on hangovers
Hypoglycemia

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