A Contagious Disorder: Folie à Deux and Dementia

Am J Alzheimers Dis Other Demen. 2018 Nov;33(7):415-422. doi: 10.1177/1533317518772060. Epub 2018 May 17.


Background: Folie à deux is a clinical condition that was first described in 19th century. It is a psychotic disorder in which two closely associated individuals share a similar delusional system.

Objectives: The aim of this article is to review the nosological significance of folie à deux and to explore the disorder among patients with dementia.

Methods: Medline and Google Scholar searches were conducted for relevant articles, chapters, and books published before 2017. Search terms used included dementia, folie à deux, induced delusional disorder, neurocognitive disorders, shared psychotic disorder. Publications found through this indexed search were reviewed for further relevant references.

Results and conclusion: Cases of Folie à deux involving patients with dementia are reported quite infrequently. Most of the studies on the topic consist in case reports. Clinicians are obliged to treat the disorder. They should be alert to the potential high risk inherent this psychotic syndrome.

Keywords: dementia; folie à deux; induced delusional disorder; neurocognitive disorders; shared psychotic disorder.

Publication types

  • Review

MeSH terms

  • Delusions / psychology
  • Dementia / psychology*
  • Humans
  • Interpersonal Relations
  • Risk Factors
  • Shared Paranoid Disorder / psychology*
  • Social Isolation*