Development of Addiction

    1) Experimentation
    2) More regular use
    3)  Tolerance
            a. A state in which the individual no longer responds to the drug.
            b. A higher dose is needed to achieve the same effect.
    4) Dependence
        a. A state in which the organism no longer responds to a drug.
        b. A higher dose is needed to achieve the same effect.
        c. psychological
        d. Physiological
    5) Addiction
 

**Note at each step of the development of addiction, the brain changes and each of these changes alters behavior.  The changes associated with the beginning steps are subtle and reversible; however with each step the changes become increasingly overt and more difficult to undo as the person moves towards addiction.