How does alcohol actually damage the brain?

It kills braincells and lowers dopimean cepters wich make ur amotions weaken.

I believe we do not fully understand the pathway by which alcohol acts, though there are theories developed from research of how it happens.

A prominent theory states that alcohol inhibits NMDA receptors and therefore inhibits long term potentials, which are believed to be associated with memory.

In biological terms:
NMDA are receptors that are activated by the neurotransmitter glutamate. When glutamate is released and activates NMDA, there is an excitatory action potential. Typically, an influx of cations into the cell will trigger an action potential, such as Na+ coming into the cell. However, the NMDA receptors open channels for Ca2+ to enter the cell. Ca2+ is somewhat special because it is often a second messenger (a chemical that triggers another response). When Ca2+ enters the cell, paracrines are released, which activate the presynaptic cell to release more glutamate. This is something like a positive feedback loop and has been posed to trigger a long term potential. Essentially a long term potential is a long term effect on the firing of action potentials. Because this potential is long term, researchers believe it is associated with memory. When alcohol inhibits the NMDA receptors, a long term potential cannot be generated and therefore there is a memory lapse.

This is one theory for how alcohol may have long term effects, such as that on memory. However, this theory may not be true. In addition, alcohol has many short term effects, like making you pee a lot by inhibiting ADH secretion.

===On Brain Shrinkage===

So a few people here are saying that alcohol shrinks your brain and this is what causes brain damage.

Some studies have shown that alcohol consumption leads to a decrease in brain volume. Note that your brain naturally shrinks as you age, but alcohol seems to increase the rate.

It is true that alcohol inhibits ADH secretion, making you pee more leading to dehydration. However, this is most likely not the reason why your brain shrinks. People are dehydrated all the time and I do not believe that has been a correlation found between dehydration and brain damage, or even shrinkage. In addition, caffeine has similar effects of ADH inhibition. Again, no correlation between caffeine and brain shrinkage.

Furthermore, no studies have shown that brain shrinkage actually leads to brain damage. We just know that alcohol appears to shrink the brain and that it also causes brain damage...a long with several other effects like destroying your liver and dehydrating you.

Alcohol does not kill brain cells, but simply shrinks them. Over time it reduces the nerve function to a point that the nerve no longer functions correctly. Thats all.

by starving your brain of water, basically...

the dehydrating certain areas of the brain, you achieve the "drunken" effect... continued and prolonged use kills off brain cells by the same means

All I know is that when drinking excessive amounts without other fluids [especially water] you get dehydrated.This happens by making you pee alot, which makes you lose a lot of essential fluids as well as iodine etc. This causes the brain to shrink because, i assume, the fluids exit to attempt to hydrate the rest of the body. This causes the famous 'thumping headache'. As far as I know the long-term effects are unknown i actually havn't researched this. Logically, I could say that as the brain isn't hydrated enough, cells die?