Where does normal brain function end and pathology begin? The line can be hard to discern. That difficulty makes disease a tricky word for talking about any psychological condition. Yet disease still may be an appropriate label for psychological conditions that have extreme features with deleterious consequences. A number of voices have recently argued that disease is simply an inappropriate label for addiction, and that instead addiction and drug taking should be seen as choices like other choices in life. It is certainly legitimate to point out that strenuous acts of agency and choice are crucial to escape from addiction. Yet when addiction involves incentive sensitization of brain mesolimbic systems that produce compulsive levels of ‘wanting’, there is a sense in which ‘brain disease’ can be a legitimate description. Incentive sensitization in addiction doesn’t replace choice, it distorts choice. Incentive sensitization creates extreme parameters in the brain that can produce extraordinary addictive temptations. This causes maladaptively intense ‘wants’ that can reoccur regardless of ‘liking’ , stronger in temptation intensity than experienced by those who are not addicts. Although the term ‘brain disease’ was never used in the original formulations of the incentive-sensitization theory, neural sensitization changes in mesolimbic systems are arguably extreme enough and problematic enough for addiction to be called a brain disease.
Link to publisher's page for Evaluating the Brain Disease Model of Addiction