What Is… Folie à Deux (Shared Psychotic Disorder)

In this series, I dig a little deeper into the meaning of psychology-related terms. This week’s term is shared psychotic disorder, also known as folie à deux.

Folie à deux is the more commonly recognized name for what the DSM-5 calls shared psychotic disorder. It’s a rare condition that involves shared delusions between two or more people who are in a close relationship. The primary, or inducer, in the relationship holds the original delusional belief, and then the secondary, or induced, in the relationship comes to share the delusion.

How it develops

The disorder was first identified in the late 1800s. In 1942, psychiatrist Alexander Gralnick proposed four subtypes of folie à deux based on how the shared delusions came about:

• folie imposée (imposed psychosis): the primary imposes the delusional beliefs on the secondary
• folie simultanée (simultaneous): both people were psychotic to begin with, and came to share a delusion
• folie communiquée (communicated): the “normal” secondary maintains the delusion after separation
• folie induite (induced): a psychotic person adds new delusions to another psychotic person’s delusional system

Risk factors

Several risk factors contribute to the development of folie à deux, including:

• lengthy relationship with strong attachment, usually family members
• social isolation
• personality disorders: histrionic | dependent | schizoid, schizotypal
• personality traits: neurotic, emotionally immature, passivity, suggestibility, suspiciousness
• untreated mental illness in the primary in the relationship; most common diagnosis is delusional disorder
• cognitive impairment in the secondary
• stressful life events
• communication difficulties
• female gender

Cases of folie à deux

More than half of reported cases involve either mother-daughter or sister-sister pairs. The primary plays a dominant role, while the secondary plays a submissive role. In some cases, the entire family becomes involved; an 11-member family suicide reported in India was suspected to be due to shared psychosis.

There was a fascinating case report in the Archives of Sexual Behaviour that described a married couple involving a female primary and male secondary. The shared delusional belief was that the husband was being financially exploited by a mistress (whom he worked with) and was being given drugs and forced to have sex with her. While he did not have memories of events his wife described, he was entirely certain that they occurred and didn’t question any of it.

Treatment

In terms of treatment, perhaps the biggest challenge is getting the pair (or system) to accept the need for treatment. The atypical antipsychotics aripiprazole and quetiapine appear to be most effective for medication treatment. It helps to separate the person or people with the secondary disorder from the person with the primary disorder, as the secondary’s delusions often don’t persist following separation. One would guess that you’d need to throw a lifetime of therapy into the mix as well.

Folie à millions

In his 1955 book The Sane Society, psychologist and philosopher Erich Fromm described folie à millions as a social pathology of normalcy. Essentially, this involves socially-induced mass insanity.

In a 2021 interview with Scientific American, psychiatrist Brandy X. Lee used the term folie à millions to describe President Donald Trump’s influence over his supporters. She states, “When a highly symptomatic individual is placed in an influential position, the person’s symptoms can spread through the population through emotional bonds, heightening existing pathologies and inducing delusions, paranoia and propensity for violence—even in previously healthy individuals. The treatment is removal of exposure.”

While I have many issues with Donald Trump and those who say “how high?” when he says “jump”, I personally don’t think it’s helpful to frame that as psychosis. Similarly, I don’t think what happened with Hitler in Nazi Germany is the same phenomenon as what happens on an individual-to-individual level in shared psychotic disorder.

Paging Dr. Freud

Shared psychotic disorder sounds like a bit of a Freudian wet dream. In psychoanalytic theory, unresolved Oedipus/Electra complex issues leading to jealousy or abnormal sexualization of the relationship are thought to contribute to the development of folie à deux.

I vaguely recall when I worked in inpatient psychiatry there was one patient that was part of a suspected folie à deux, but I’ve never encountered a clear-cut case.

It’s fascinating the things the mind can do.

You can find the rest of the what is… series in the Psychology Corner.

References

• Al-Saif, F., & Al Khalili, Y. (2022). Shared psychotic disorder. StatPearls.
• Harris, N. (2019). Recovering the critical potential of social pathology diagnosis. European Journal of Social Theory, 22(1), 45-62.
• Jolfaei, A. G., Isfahani, M. N., & Bidaki, R. (2011). Folie à deux and delusional disorder by proxy in a family. Journal of Research in Medical Sciences: The Official Journal of Isfahan University of Medical Sciences, 16(Suppl1), S453.
• Lew-Starowicz, M. (2012). Shared psychotic disorder with sexual delusions. Archives of Sexual Behavior, 41(6), 1515-1520.
• Lewis, T. (2021). The ‘shared psychosis’ of Donald Trump and his loyalists. Scientific American.
• Sharon, I. (2018). Shared psychotic disorder. Medscape.
• Tamminga, C. (2022). Shared psychosis. Merck Manual Professional Version.
• Wikipedia: Folie à deux

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