The progressive nature of alcohol abuse and dependence must also be considered when attempting to determine an effective treatment. Progression from alcohol experimentation to dependence is not always linear in nature, with individuals often returning to earlier stages of the disease process before advancing to the final stages of dependence. The positive-reinforcement aspects of alcohol (e.g., euphoria) that drive the disease early on, are usually replaced by negative-reinforcement aspects (e.g., removal of anxiety or withdrawal) in the later stages of the addiction cycle. This makes alcohol dependence very difficult to treat. An effective animal model of alcoholism should display both the positive-and negative-reinforcement aspects of the disease so that the effectiveness of different compounds can be evaluated for each aspect.
