No one knows how many times a person can use a drug without changing his or her brain and becoming addicted.
A person's genetic makeup probably plays a role. But after enough doses, an addicted teen's limbic system craves the drug as it craves food, water, or friends. Drug craving is made worse because of down regulation.
Without a dose of the drug, dopamine levels in the drug abuser's brain are low. The abuser feels flat, lifeless, depressed. Without drugs, an abuser's life seems joyless. Now the abuser needs drugs just to bring dopamine levels up to normal levels. Larger amounts of the drug are needed to create a dopamine flood or high, an effect known as tolerance.
By abusing drugs, the addicted teen has changed the way his or her brain works. Drug abuse and addiction lead to long-term changes in the brain. These changes cause addicted drug users to lose the ability to control their drug use. Drug addiction is a disease.
There is no cure for drug addiction, but it is a treatable disease; drug addicts can recover. Drug addiction therapy is a program of behavior change or modification that slowly retrains the brain. Like people with diabetes or heart disease, people in treatment for drug addiction learn behavioral changes and often take medications as part of their treatment regimen.