Addiction does begin with drug abuse when an individual makes a conscious choice to use drugs, but addiction is not just "a lot of drug use". Recent scientific research provides overwhelming evidence that not only do drugs interfere with normal brain functioning creating powerful feelings of pleasure, but they also have long-term effects on brain metabolism and activity. At some point, changes occur in the brain that can turn drug abuse into addiction, a chronic, relapsing illness. Those addicted to drugs suffer from a compulsive drug craving and usage and cannot quit by themselves. Treatment is necessary to end this compulsive behaviour. This book includes within its scope leading-edge research on cocaine and heroin abuse.