Folie a trois in a multilevel security forensic treatment center: forensic and ethics-related implications.

Shared (Induced) Delusional Disorder commonly occurs in close relationships and involves a varying number of participants who may be nonconsanguineous. The disorder has been associated with forensic and fatal consequences. Its occurrence in three nonrelated, incarcerated individuals is described in this article. This case of folie à trois has forensic implications and raises several questions of ethics that relate to autonomy, confidentiality, safety, and risk estimation. The presentation, management, and outcome of the patients suggest that a high index of suspicion is needed to detect cases in similar settings. The report concludes that the rarity of the disorder in a forensic mental health population may be the result of underdetection, given that conditions are conducive to the development of the disorder. Telltale signs of its manifestation are hypothesized as being responsible for some events in incarcerated populations. Physical separation and antipsychotic medications remain the mainstay of treatment.