Are there Neurological Correlates for Cotard’s Delusion?

Review of Kudlur, S., George, S. & Jaimon, M. (2007), “An overview of the neurological correlates of Cotard syndrome,” Eur. J. Psychiat. 21(2), 99 – 116.

Even though not mentioned in DSM-IV-TR, hands down Cotard’s Delusion (CD; also known as Cotard’s Syndrome) wins the competition for the most interesting psychiatric disorder around.  Discovered (some might say, invented) by the French physician Jules Cotard, it is the belief one does not exist (“delire de negation”).  This is philosophically perplexing because if one does not exist then it is difficult to see how one could have CD.  CD is related to other curious mental diseases such as Capgras Syndrome (the belief one’s close acquaintances have been replaced by impostors).

In my opinion the key question about CD is its etiopathogenesis, that is, if it has neurological correlates or if it simply is a pathology of belief.  The authors of this paper attempt to discern whether CD has any such connections.  In a non-experimental study they reviewed over 100 journal articles.  They constrained for organic conditions including typhoid fever, temporal lobe epilepsy, brain tumors and brain injuries.  The most commonly reported neurological abnormalities in these patients included structural changes to brain anatomy (such as cerebral atrophy), functional brain changes (such as hypoperfusion in the frontal cortex) and various neuropsychological abnormalities (such as impaired face recognition, itself a shade-off into Capgras Syndrome).  They were unable to discern any reported neurochemical relationships.

The authors were unable to make a case for CD having any neurophysiological relationships.  From a design standpoint they failed to consider the possible impact of intermediate confounding variables (such as environmental stressors), which may be more of a substantial causal factor.  This leaves CD in the undesirable posture of being a clinical disorder without a well-defined etiology – more of a philosophical problem than a real one.