With holidays just around the corner, that can only mean one thing: time to get your drink on! (not that we needed an extra reason to drink this year) Scientists have conducted many studies investigating the effects of alcohol consumption on the brain, but, while their results are, no doubt, interesting and we should take them into account when evaluating our general alcohol consumption habits, they also tend to be less on the cheerful side. And since we could all use a break from the “not so cheerful” stuff, we’ve decided to keep it basic today, so we’ll just look at some good old-fashioned “fun” facts: how exactly does alcohol reach your brain and what are the mechanisms through which it produces its well-known effects?
Normally, alcohol which enters the body is processed by the liver. More specifically, an enzyme called alcohol dehydrogenase breaks it down into another molecule named acetaldehyde, which is eventually transformed into acetic acid. Nevertheless, there is only so much alcohol which can be processed by the liver within a specific amount of time, so when you drink more than that, that’s when the fun begins. Alcohol which is not metabolized in the liver can be absorbed into the bloodstream and from there, it can further travel into the brain. Of course, you might remember from some of our previous posts that the brain is protected by the blood-brain barrier, i.e. an extra layer of protection which prevents most molecules and microorganisms from reaching your brain. (Un)fortunately, this barrier is permeable for alcohol.
Once it enters the brain, alcohol is capable of affecting its chemistry indirectly, through two neurotransmitters: GABA and glutamate. Neurotransmitters are the chemical messengers of the body; they are responsible for carrying messages from one neuron to the other, as well as from neurons to other cells (such as the muscle cells). Furthermore, they come in two flavours: either excitatory (meaning that they lead to an increase in activity), such as glutamate, or inhibitory (they cause a decrease in activity), such as GABA (gamma aminobutyric acid). Alcohol basically boosts the effects of GABA, while inhibiting glutamate. Changing the activity profile of these neurotransmitters is why increased alcohol consumption leads to slurred speech, decreased inhibition (many people report that alcohol makes them less socially anxious, for example), slower information processing, as well as slower thinking.
However, while the above-mentioned effects are the result of alcohol influence in the cerebral cortex, other areas of the nervous system are also affected. For example, when drinking, the cerebellum, which is involved in coordination and motor control, is also influenced by alcohol, that is why drunk people have trouble maintaining their balance. The hypothalamus and pituitary, two glands involved, among others, in controlling proper sexual functioning, are depressed by alcohol. In consequence, even though sexual desire might increase after consuming alcohol, performance actually decreases.
Finally, the effects of alcohol on the medulla, the part of the nervous system responsible for automatic functions such as breathing, consciousness, and body temperature, are what cause sleepiness and, in some cases, even slow breathing and lower body temperature. The medulla also contains the emetic (vomiting) center, the one that decides whether a toxic substance has entered the body and stomach emptying should be initiated. This area receives information from its next-door neighbour, the chemoreceptor trigger zone (CTZ), a small sensory area which actually detects the toxic substance and sounds the alarm. So following increased alcohol consumption, it is the CTZ that tells your emetic center to open the valves.
As you can see, alcohol doesn’t just “get you drunk”, it actually influences many parts of your nervous system and produces a range of effects. And while knowing this information doesn’t objectively improve much in your life, it might at least give you some fun facts to throw into the upcoming potentially long awkward silences.
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