LB: In the first stage of our project PERFECT we are going to ask whether delusions can have pragmatic and epistemic benefits. You and your collaborators have noticed how anosognosia (denial of illness), despite initially interfering with rehabilitation, can then lead to lower anxiety and protect from negative emotions (Aimola Davies et al., 2009). Can you think of other examples of delusions having a positive psychological impact?
MKD: Let me begin by reviewing the findings that you mentioned in your question. Some researchers distinguish denial of illness from anosognosia and use the ‘denial’ terminology for cases with a ‘psychological’ rather than neurological aetiology. In our paper, we referred to a theoretical review by Kortte and Wegener (2004), who found support for both adaptive and maladaptive effects of denial of illness across a range of rehabilitation populations.
They proposed two distinctions to explain these different effects: (i) subtypes of denial and (ii) different time points from symptom identification to hospitalisation and rehabilitation. On (i), they suggested that the effect of avoidance of illness-related information is more likely to be maladaptive while a positive reinterpretation of the illness experience was more likely to be adaptive. On (ii), and focusing now on Kortte and Wegener’s discussion of denial of heart disease, denial at the stage of symptom (self-)identification has obvious negative consequences and long-term denial (particularly, of the avoidance type) after discharge from hospital has been linked with poorer compliance with medication regimes and a failure to heed medical advice about risk factors. However, denial (particularly, of the positive reinterpretation type) during the hospitalisation stage appears to be associated with more positive effects, such as protection from negative emotional states and reduced medical complications.