How and why does the body/brain become “alcohol dependent” after continuous drinking? And what makes it possible for an alcoholic to experience seizures, hallucinations, heart failure, etc. (the “DTs”) when they stop drinking?
In: Biology
Physiological dependence occurs because alcohol (ethanol, which is the principal form of alcohol in booze) binds to receptors that normally take a molecule called GABA (gamma aminobutyric acid), which primarily works as a depressant for the central nervous system. GABA is usually produced in a way that balances out a different molecule called glutamate, which primarily works as to excite the central nervous system. When ethanol increases the activity at GABA receptors continuously, the brain becomes accustomed to that artificial influence and decreases its natural production – the balance of GABA and glutamate receptor activity, on average, “appears” balanced to the brain’s normal mechanisms.
Ceasing to consume ethanol leaves the brain with a lower-than-normal amount of GABA receptor activity, and either a normal or increased amount of glutamate production and receptor activity, resulting in over-excitement of the CNS. This can have effects ranging from unpleasant (shakes, confusion, mild anxiety) to very distressing or even life-threatening (alcoholic hallucinosis, delirium tremens, seizures) because the excess glutamate causes the nervous system to be active in ways that it should not normally be.
EDIT: It is also worth mentioning that something very similar happens with other GABAergic drugs such as benzo- and thienodiazepines (e.g. alprazolam, diazepam, etc.). This is why benzo withdrawal can be similarly dangerous.
The brain produces chemicals it needs to function normally and ethanol puts up a wall blocking their action. In response the output of those chemicals is increased to compensate.
If you were to suddenly remove the wall, the now high dose of those chemicals cause all kinds of nasty effects, including death. They must be brought off the drug slowly.
I don’t think it’s ever dependent. Alcohol is sort of a stimulant to forget. And it makes people feel better.
Let’s say your brain is a pet frog. Your frog goes out and catches flies to feed itself. Suddenly, you start to bring flies to your frog. At first, it still goes out and catches flies, but as you keep bringing more and more flies regularly, your frog no longer goes out to catch flies. And then, it forgets how to go out and hunt them. Your frog is now dependent on you for flies the way your brain is dependent on your drinking for certain chemicals that alcohol releases. If you stop drinking, it would be like if you stopped feeding your frog. It would freak out, go hungry, and potentially die if it can’t remember how to catch flies itself. You have to wean your frog off the flies you’ve been supplying and teach it to catch them again just like you have to adjust your brain to no longer having alcohol.
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