When GABA binds to its receptors, channels in the neuron flicker open and closed, allowing negatively charged molecules called ions (shown here in white) to move into the neuron. This decreases the neuron's activity.
This close-up shows the opening of the ion channels in normal GABA binding, and then when alcohol is added.
Alcohol, shown in black, also binds to the GABA receptors, and increases the quieting effect that GABA has on neurons. Researchers are not sure exactly how it does so, but one theory holds that it causes the ion channels to stay open longer, thus increasing the ion flow. The result is a much greater quieting effect on the brain.
Because there are GABA receptors in many parts of the brain, many different parts are affected. This accounts for alcohol's sedating effect on many functions controlled by the brain--judgment, movement, and even breathing.
Unfortunately, prolonged alcohol use may cause the brain to adapt, so it comes to depend on the presence of alcohol to function normally. Then, if the person stops drinking, he or she experiences anxiety, jitteriness, emotional discomfort, insomnia, possibly tremors, and, in severe alcoholism, sometimes convulsions and/or death.
Even long after the person has stopped drinking alcohol, brain abnormalities can persist, causing feelings of discomfort and craving for more alcohol to relieve these feelings.