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.
Within the disease model of addiction, a genetic predisposition is believed to be present. An environmental event is also felt likely to be required. These hypotheses would explain the result of adoption and twin studies that have been carried out, indicating that twins separated at birth have a higher likelihood of concordance for addictive disease than would be expected were there not a genetic component, and indicating that these twins have a lower likelihood of concordance for addictive disease than do twins who remain together in identical environments.
Critics of the disease model, particularly those who ascribe to the life-process model of addiction argue that labeling people as addicts keeps them from developing self-control and stigmatizes them. They also argue that the disease approach has not discovered any biological mechanisms to identify addictive behavior, and that it therefore does not fit the definition of disease. However, such arguments are premised upon an incorrect medical definition of disease, which in reality does not require that a mechanism necessarily be identified. As noted by addiction medicine specialist Drew Pinsky, MD:
|“||A disease is a complex relationship between the genetic makeup of the individual and the environment that results in an abnormal state of physiology (called pathophysiology) reflected in signs and symptoms. Those signs and symptoms follow a predictable pattern (called a natural history). And that natural history has a predictable response to treatment.||”|
- Leshner, Alan I., Addiction Is a Brain Disease, and It Matters, Science 3 October 1997: Vol. 278. no. 5335, pp. 45 - 47
- Prescott, Carol A., and Kendler, Kenneth S. (January, 1999). Genetic and Environmental Contributions to Alcohol Abuse and Dependence in a Population-Based Sample of Male Twins,” American Journal of Psychiatry, Volume 156/ January, 1999, p. 34-40.