Alcohol is a depressant, which means it slows the function of the central nervous system (a person’s brain and spinal cord). Alcohol actually blocks some of the messages trying to get to the brain. This alters a person's perceptions, emotions, movement, vision, and hearing.
In adolescence, brain development is characterized by dramatic changes to the brain’s structure, neuron connectivity (i.e., “wiring”), and physiology. Alcohol can cause change the structure and function of the developing brain, which continues to mature into a person’s mid 20s, and it may have consequences reaching far beyond adolescence.
When alcohol affects the frontal lobes of the brain, a person may find it hard to control his or her emotions. Alcohol can increase the likelihood of a person acting without thinking, losing reason and inhibitions, or even becoming violent. Drinking alcohol over a long period of time can damage the frontal lobes forever.
Alcohol slows down a person's reaction time and may limit fine motor skills.
Alcohol can cause blurred or distorted vision and poor distance judgement.
Alcohol can increase a person's blood pressure, hunger, thirst, and the urge to urinate. Alcohol can also cause slurred speech and can cause a person to have trouble remembering something he or she just learned, such as a name or a phone number.
After drinking alcohol, a person lacks muscle coordination and balance. Their hands may be so shaky that they can't touch or grab things normally.
When alcohol affects this part of the brain, a person will start to feel sleepy. Increased consumption can lead to unconscious. Alcohol also decreases a person's body temperature, putting them at increased risk for hypothermia.