A hypothesis on Cotard's syndrome as an evolution of obsessive-compulsive disorder.

Cotard's syndrome usually presents as combined symptoms occurring in a broad series of neurological, psychiatric, and medical disorders, being severe depression the most frequent. The syndrome is not classified as a distinct clinical entity in the nosological systems but appears solely as a clinical condition in case reports. Thus, the diagnosis of Cotard's syndrome mainly centres on the psychiatric interview and the ability of the clinician to recognise specific symptoms due to the absence of both clinical instruments and diagnostic criteria. Cotard's syndrome has never been described to date in patients with a history of obsessive-compulsive disorder (OCD). We report a case of a 49-year-old woman presenting obsessive symptoms and related compulsions for more than 30 years. Cotard's syndrome appeared after 3 years from a tragic event that had caused a psychological trauma. Such an occurrence may have contributed to worsening OCD and leading to a second major depressive episode followed by a suicidal attempt. Since then, the subject of our patient's obsessive thoughts changed, and the belief of being dead appeared. The repetitive and stereotyped thoughts caused severe distress, and accompanied the compulsive nature of reassurance seeking, temporarily beneficial to the anxiety arousing. The transition from obsession to delusion occurred when resistance was abandoned, and insight was lost. Once Cotard's syndrome had stabilised, OCD was no longer present. Additional distinctive features were the absence of psychiatric family history and the persistent nature of the affective psychosis. We concluded that Cotard's syndrome represented the evolution of the initial obsessive-compulsive disorder. Furthermore, we differentiated the clinical condition of our patient from other psychiatric diseases with similar clinical features. Larger-scale research is needed to consider topics other than comorbidity and also to explore significant elements of the patient's clinical history to discover what may influence the evolution and/or the persistence of the diseases.