Heavy alcohol consumption-even on a single occasion-can throw the delicate balance of neurotransmitters off course. Alcohol can cause your neurotransmitters to relay information too slowly, so you feel extremely drowsy. Alcohol-related disruptions to the neurotransmitter balance also can trigger mood and behavioral changes, including depression, agitation, memory loss, and even seizures.
Long-term, heavy drinking causes alterations in the neurons, such as reductions in the size of brain cells. As a result of these and other changes, brain mass shrinks and the brain's inner cavity grows bigger. These changes may affect a wide range of abilities, including motor coordination; temperature regulation; sleep; mood; and various cognitive functions, including learning and memory.
One neurotransmitter particularly susceptible to even small amounts of alcohol is called glutamate. Among other things, glutamate affects memory. Researchers believe that alcohol interferes with glutamate action, and this may be what causes some people to temporarily "black out," or forget much of what happened during a night of heavy drinking.
Alcohol also causes an increased release of serotonin, another neurotransmitter, which helps regulate emotional expression, and endorphins, which are natural substances that may spark feelings of relaxation and euphoria as intoxication sets in. Researchers now understand that the brain tries to compensate for these disruptions. Neurotransmitters adapt to create balance in the brain despite the presence of alcohol. But making these adaptations can have negative results, including building alcohol tolerance, developing alcohol dependence, and experiencing alcohol withdrawal symptoms.