Perhaps there is no other illness to which the saying "an ounce of prevention is worth a pound of cure" is more applicable than it is to substance abuse and dependence. The reason for this is that once a person becomes dependent on, or addicted to, alcohol or some other drug, certain physiological changes occur inside the body, which make it extremely difficult to give up using that particular substance. For example, alcohol affects a variety of neurotransmitters (chemicals that help transmit messages between brain cells), and the overall effect is the inhibition or reduction of brain cell activity. When alcohol is removed, the affected nerve cells are overstimulated, and this results in craving. Similar changes also take place when a person abuses other drugs, such as heroin or cocaine, and some of the brain cells may become permanently damaged in the...