Delusional misidentification syndromes in obsessive-compulsive disorder.

Delusional misidentification syndromes (DMS) have been rarely reported in patients with conditions other than schizophrenia-related disorders, diffuse brain disease (dementia) and focal neurological illness. In this report, we describe DMS (i.e. Capgras and Fregoli syndromes) in two patients with severe and treatment resistant obsessive-compulsive disorder (OCD), one with paranoid personality disorder (PPD) and the other with a pervasive developmental disorder (PDD) not otherwise specified. While our findings highlight an interesting phenomenon (the occurrence of DMS in OCD), it is presently unclear whether this association is rare or underreported. Misidentification syndromes might be the ultimate result of a combination of obsessive fears and preexisting cognitive bias/deficits, such as mistrustfulness (in PPD) or poor theory of mind (in PDD).