Objectives: To assess the effect of age at onset on the phenomenology of Cotard's syndrome (CS) as a recent study reported a high rate of occurrence of bipolar disorder (BD) in adolescents and young adults with CS followed up for ≥2 years.
Methods: We reviewed all cases of CS reported since it was first described. A statistical analysis was carried out to determine the effect of age at onset on CS phenomenology.
Results: We found 138 cases including 21 cases aged 25 years or younger. In these younger CS patients, BD was more frequent, and the risk of associated BD was increased nine times (p < 0.0001). Within the BD sub-group (n = 27), admixture analysis identified two sub-groups with mean ages at onset of 18.7 years [standard deviation (SD) = 3.2] and 50.5 years (SD = 11.7).
Conclusions: Young people with CS should be monitored carefully for the onset of BD, and families should be educated about this risk. Treatment with mood stabilizers can be helpful for those who develop BD. Within BD associated with CS, early versus late onset should be distinguished.