Mechanistic models for understanding addiction as a behavioural disorder. (original) (raw)

The very understanding of addiction as a disease is controversial, as is the best way to explain it. Psychiatry is dominated by a version of the medical model that sees psychopathologies as diseases whose observable symptoms are causally explained by abnormalities in underlying neu-robiological systems. Although addictions seem similar in terms of symptoms, they can vary widely in their consequences and pathology. Many conceptions of addiction see the symptoms as primarily behavioural or psychological, defining it in terms of phenomena like craving (Elster 1999) or in economic terms (Ross et al. 2008). However, even if these psychological or economic theories of the phenomena are correct, there is still room for exploring the logic of the causal explanations that comport with the medical model. This is because the medical model can be seen as an application to psychiatry of the commitments of cognitive neuroscience (Murphy 2006) and the dominant approach in the cognitive neurosciences is that human behaviour consists of capacities that can be analysed into other personal level capacities (Cummins 2000). In turn, these can then be situated within a hierarchy of biological processes. Personal-level phenomena can be broken down into their component processes and these processes can be understood, typically in representational terms, as the outputs of sub-personal systems that do things like assign a meaning to a phonological representation or compute visual edges. This decomposition of the task and the allocation of the subtasks to interacting physical entities gives the general form of a mechanistic explanation. In this chapter we will discuss the application of this mechanistic perspective to addiction. It is important to note at the outset that mechanistic explanations are a specific type of causal explanation. Not all phenomena admit of mechanistic explanations, and not all causal explanations can be expressed in terms of mechanisms. What distinguishes a mechanistic explanation is that it depends on the spatial arrangement of component parts and the nature of their interactions. In the neurosciences we expect to identify processes that can be assigned to parts of the brain, where they will be revealed as the outcome of mechanisms-interacting systems of biological components. If it is the right approach, it will work throughout cognitive neuroscience. So, even if addiction is best understood as neither a disorder nor a fundamentally neurological phenomenon , proponents of the mechanistic approach would still expect to explain it in the terms we will present, provided that we can explain the features of addiction as the result of interacting neurological systems. Addiction does not have to be a pathological phenomenon in order to receive a mechanistic explanation.