Alcohol affects the brain by altering the way neurotransmitters work, claims HowStuffWorks. Neurotransmitters are chemicals that regulate the electrical signals the nerves send to each other. Because of this, neurotransmitters regulate just about every system in the body.
Alcohol especially affects inhibitory neurotransmitters, which lower the electrical activity in the brain, says HowStuffWorks. The inhibitory neurotransmitter that alcohol mostly affects is GABA, or gamma-aminobutyric acid. Alcohol increases GABA's inhibitory effects, and this is the reason for the lack of coordination and slurred speech that occur when a person has had too much to drink.
Alcohol also inhibits glutamate, which is an excitatory neurotransmitter, and increases the effects of dopamine, claims HowStuffWorks. This causes even more of the physiological systems in the body to slow down while enhancing pleasurable feelings. Alcohol works on the cerebral cortex in a way that makes a person less able to make good decisions while making his behavior less inhibited. It affects the centers of balance in the cerebellum, and it affects the areas in the brain that control hormones in ways that make a person desirous of sex but unable to perform.
Alcohol also affects the brain's medulla, which controls breathing, temperature and consciousness, says HowStuffWorks. Alcohol can have a life-threatening depressive effect on breathing and body temperature.