High Quality Content by WIKIPEDIA articles! The disease model of addiction describes an addiction as a lifelong disease involving biologic and environmental sources of origin. The traditional medical model of disease requires only that an abnormal condition be present that causes discomfort, dysfunction, or distress to the individual afflicted. The contemporary medical model attributes addiction, in part, to changes in the brain's mesolimbic pathway. The medical model also takes into consideration that such disease may be the result of other biologic, psychologic, or sociologic entities despite an incomplete understanding of the mechanisms of these entities.