“…It was first described as folie à deux by Lasegue and Falret in 1877 (Joshi, Frierson, & Gunter, 2006). In the literature, folie à deux is described typically in case reports (Adler & Magruder, 1946; Florez & Gomez-Romero, 2001; Gant & Brown, 2001; Joshi et al, 2006; Oatman, 1947; Petrikis, Andreou, Karavatos, & Garyfallos, 2003; Reif & Pfuhlmann, 2004; Shiwach & Sobin, 1998), so definite prevalence rates are lacking. Generally, it is perceived as a rare condition of unclear etiology, intriguing as a “nature or nurture” phenomenon, and challenging our understanding of the roots of psychopathology.…”