Cotard Delusion - Pathophysiology

Pathophysiology

The underlying psychopathology and neurophysiology of Cotard's Syndrome may be related to other problems involving delusional misidentification. Neurologically, Cotard's is thought to be related to the Capgras delusion, and both are thought to result from a disconnect between the brain areas that recognize faces (fusiform face areas) and the areas that associate emotions with that recognition (the amygdala and other limbic structures). This disconnection creates a sense that the observed face is not the person's it purports to be, and therefore lacks the familiarity that should be associated with it. The disconnect results in a feeling of derealization. If it is the face of a person known to the sufferer, it is experienced as an impostor's (Capgras); if the sufferer sees their own face they may feel no association between it and their sense of self, resulting in a sense that they do not exist. Literature shows that Cotard's is associated with lesions in the parietal lobe. Patients with Cotard's generally have more brain atrophy than control groups and more median frontal lobe atrophy in particular.

Cotard's syndrome is encountered primarily in psychoses such as schizophrenia. It can arise in the context of neurological or mental illness and is particularly associated with depression and derealization. It has even been described in migraine.

Cotard delusion has also been the result of adverse drug reactions to (val)acyclovir. The symptoms were associated with high serum concentrations of CMMG, the principal metabolite of acyclovir. Patients with impaired renal function seem to be at risk even after dose reduction; in the cited case, haemodialysis cured the delusions in a few hours and it is suggested that this mental state may not always be a cause for psychiatric hospitalization.

Research shows that culture has an impact on the biographical experiences expressed by patients who suffer from Cotard's. This finding supports Bering's view of a cognitive system dedicated to forming illusory representations of immortality. Mainstream thought is that these illusory representations of immortality and other delusions evolved in response to sociological pressures.