Drug addiction is a brain disease. Every type of drug of abuse has its own individual mechanism for changing how the brain functions.

But regardless of which drug a person is addicted to, many of the effects it has on the brain are similar: they range from changes in the molecules and cells that make up the brain, to mood changes, to changes in memory processes and thinking, and sometimes changes in motor skills such as walking and talking. And these changes have a huge influence on all aspects of a person’s behavior.

A drug can become the single most powerful motivator in a drug abuser’s existence. He or she will do almost anything for the drug. This comes about because drug use has changed the individual’s brain, their behavior, their social and other functioning in critical ways.