Top-down causation in psychiatric disorders: a clinical-philosophical inquiry

Psychiatry has long debated whether the causes of mental illness can be better explained by reductionist or pluralistic accounts. Although the former relies on commonsense scientific bottom-up causal models, the latter (which typically include environmental, psychological, and/or socio-cultural risk factors) requires top-down causal processes often viewed with skepticism, especially by neuroscientists. We begin with four clinical vignettes which illustrate self-interventions wherein high-order psychological processes (e.g. religious beliefs or deep interpersonal commitments) appear to causally impact the risk for or the course of psychiatric/behavioral disorders. We then propose a model for how to understand this sort of top-down self-causation. Our model relies centrally on the concept of a control variable which, like a radio tuning dial, can implement a series of typically unknown physical processes to obtain the desired ends. We set this control variable in the context of an interventionist account of causation that assumes that a cause (C) produces an effect (E) when intervening on C (by manipulating it) is associated with a change in E. We extend this framework by arguing that certain psychological changes can result from individuals intervening on their own mental states and/or selection of environments. This in turn requires a conception of the self that contains mental capacities that are at least partially independent of one another. Although human beings cannot directly intervene on the neurobiological systems which instantiate risk for psychiatric illness, they can, via control variables at the psychological level, and/or by self-selection into protective environments, substantially alter their own risk.