Where does normal brain or psychological function end, and pathology begin? The line can be hard to discern, making disease sometimes a tricky word. In addiction, normal 'wanting' processes become distorted and excessive, according to the incentive-sensitization theory. Excessive 'wanting' results from drug-induced neural sensitization changes in underlying brain mesolimbic systems of incentive. 'Brain disease' was never used by the theory, but neural sensitization changes are arguably extreme enough and problematic enough to be called pathological. This implies that 'brain disease' can be a legitimate description of addiction, though caveats are needed to acknowledge roles for choice and active agency by the addict. Finally, arguments over 'brain disease' should be put behind us. Our real challenge is to understand addiction and devise better ways to help. Arguments over descriptive words only distract from that challenge.