|Credit: Wellcome Library, London|
The focus of the talks by Phil Corlett (School of Medicine, Yale University, US) and Kengo Miyazono (Philosophy, Keio University, Japan) was the relative merits of theories of delusion formation (prediction-error theories versus two-factor theories), but I kept thinking about how interesting the case of delusions is for understanding the relationship between mental health and success, and indeed this was a recurrent theme in the discussion following the talks.
When we think about delusions, we tend to think about the most distinctive mark of madness, and about their disruptive effect on people's lives. And although it would be a mistake to construct delusions as radically discontinuous from the irrational beliefs we all have, their adverse impact on wellbeing should not be underestimated. Thanks to the talks at today's seminar, we reflected on how delusions come about and this led us to realise that delusions may be a response (some would even say: an adaptive response) to a crisis. If we believe the prediction-error theory of delusion formation, in the prodromal stage of psychosis (before delusions develop) people experience hyper-salience. Their experience becomes salient: noises are louder, colours are brighter, apparently random events assume special significance, and there is no explanation available for this change that is overwhelming and distressing.
When the delusion emerges, it presents itself as an explanation for the change. Things become less mysterious and unpredictable, the person seems to gain some sort of control by imposing meaning over previously puzzling events. For a short time then delusions provide a relief, they allow the person to engage with the physical and social environment that had become so difficult to predict and interpret, and can be seen as psychologically and epistemically beneficial (see this paper for a more detailed account). Such benefits do not last long, as the delusion may be distressing in its own right, due to its content, and may become a new source of anxiety by creating a gulf between the person and others who do not share the delusion. Moreover, it can give rise to further beliefs that are consistent with it, and prevent the person from accessing a shared reality.
Interestingly, when a strange belief is shared (where we want to call it delusional or not will depend on whether we believe that the term 'delusion' should be reserved to clinical cases) the adverse effects seem to be mitigated. The example of bizarre religious beliefs in small communities was mentioned today, and evidence suggests that such beliefs do not impact negatively on the functioning of the people who live by them. Thus, at its adoption stage the delusion can be seen as adaptive by helping a person overcome hyper-salience and reconnect with the surrounding environment, but at its maintenance stage the delusion can become a serious threat to wellbeing and good functioning, especially when it prevents socialisation.
The distinction between different stages of the development of the delusion can be clinically relevant to the choice of treatment options, and contribute to a better understanding of the intricate relationship between mental health and success. What if, as Roberts (1991) suggested, the delusion were the first step towards remission?