Delusional Misidentification Syndromes in Postpartum Psychosis: A Systematic Review.

Introduction: Delusional misidentification syndromes (DMS) are a group of psychopathological experiences occurring in psychosis, involving the misidentification of a person or place. DMS are often accompanied by hostility towards the object of delusional misidentification. This is of a particular concern in perinatal mental illness due to the potential disruption of the mother-infant bond, and risk of neglect, violence, or infanticide towards a misidentified child. This review aimed to collate all published cases of DMS in postpartum psychosis to further understand how these syndromes present in perinatal mental illness.

Methods: In August 2021, an online database search was conducted using PubMed, MEDLINE, PsycINFO, CINAHL, and Embase to identify all publications reporting DMS in the perinatal period.

Results: Nine papers were included in the review involving 8 case reports of Capgras syndrome and one case series involving 4 cases of Fregoli syndrome. Three cases identified organic pathology, which may have contributed to the presentation. The most common subject of misidentification was the patient's husband (n = 7), followed by their baby (n = 6), hospital staff (n = 4), other family members (n = 3), and self (n = 1). Five cases remark on the impact of perinatal illness on the maternal-infant bond, of which four result in the mother being unwilling to care for the infant as the result of their delusional beliefs.

Conclusion: This is the first systematic review of the literature in this field. Although small in number, these cases reveal several important learning points including that DMS can occur with or without underlying organic disease. Active exploration of the nature of delusions in postpartum psychosis is required to mitigate the risk of harm to the infant and mother-infant bond. It may also uncover that these syndromes are more common in postpartum psychosis than previously realized.