Question: What causes the Cotard delusion?

Jack barton answered on 20 Jun 2017:

Ah this is more my territory – weird things in psychology! Firstly, if you are interested in these sorts of things then Oliver Sacks and Richard Wiseman are great starting points.

Cotard delusion, the strong belief that you are dead, is one with limited research which has broadly focused on individual case studies. As with other delusions the individual will ignore powerful evidence to the contrary of their belief (e.g. hearing their own heartbeat).

The delusion and associated syndrome can occur alongside a range of psychiatric and physical illnesses (e.g. depression, schizophrenia, Parkinson’s disease and stroke). Although brain scans show relatively normal brain activity for those who experience cotard delusions, it has been argued that a damaged ability to produce the appropriate emotional response to the self may play a role. We no longer recognise our body as familiar even though it looks like our own.

For example, this explanation has been used for capgras delusion where an individual may believe a loved one has been replaced by a body double. In this case, an inappropriate or absent emotional response is produced in response to the presence of loved ones. The lack of this response is in turn then interpreted at the family member in front of you being a fake – their presence doesn’t feel like your partner, mom, dad, etc. The conviction attached to this delusion then makes it distressing and problematic as evidence to the contrary is explained away.

In terms of treatment for cotard delusions, there is evidence to suggest that electroconvulsive therapy (ECT) can have positive effects. Can this shed light on what causes the delusions? Not especially, as ECT has a widespread effect on the brain and it is hard to pinpoint what it may be remedying.