Drug and alcohol abuse are very prevalent in our society today. Drugs of abuse mimic neurotransmitters, in that they produce similar chemical activity in the nervous system. When too many drugs or too much alcohol are used for too long, the body's natural production of neurochemicals may shut down.

Interestingly, each drug of abuse (including alcohol) appears to mimic one or more chemicals in the nervous system. For example, heroin appears to chemically resemble endorphin, cocaine resembles dopamine, and alcohol emulates gamma aminobutyric acid.

When an individual regularly consumes drugs or alcohol without allowing adequate time between doses, the drug's surrogate chemical in the nervous system may become depleted or altered in such a manner as to produce chemical imbalance. Ideally, when the person stops drinking alcohol or taking drugs, his or her brain will be able to correct the imbalance. However this will require a period of abstinence for the brain to start properly functioning again, this period is generally called withdrawal.

The abuse of alcohol contributes to many deaths per year in the United States. One of the most common drug overdoses leading to death is ingestion of a large amount of alcohol. Chronic alcohol abuse leads to liver disease. Liver disease can be manifested as fatty change. Excessive alcohol ingestion for many years can lead to micronodular cirrhosis. A cirrhotic liver leads to portal hypertension and the complication of bleeding esophageal varices with massive, life-threatening gastrointestinal hemorrhage. There is also an increased risk for hepatocellular carcinoma arising in a cirrhotic liver. In the brain, alcoholism can lead to Wernicke's disease.