What Is Shared Psychotic Disorder?

Shared psychotic disorder refers to the spreading of delusions from a person with mental illness to a close secondary person.

January 17, 2025 · 7 min · 1437 words · Lynn Mcmahon MD

Table of Contents

Table of ContentsView AllTable of ContentsWhat Is Shared Psychotic Disorder?SymptomsCausesDiagnosisTreatmentCoping

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Table of Contents

What Is Shared Psychotic Disorder?

Symptoms

Causes

Diagnosis

Treatment

Coping

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Shared psychotic disorder is a rare type of mental illness in which a person who does not have a primary mental health disorder comes to believe thedelusionsof another person with apsychoticor delusional disorder. For example, a wife might come to believe the delusions of her husband, despite having otherwise good mental health.

The incidence of shared psychotic disorder is reported to be low (1.7 to 2.6% of hospital admissions). However, it’s likely that many cases go unreported.

Unless the primary person with the mental illness seeks help or acts out in a way that draws attention, the secondary person is unlikely to look for help. This is because neither person realizes that the delusions are not real.

Shared psychotic disorder can also appear as a group phenomenon, in which case it has been referred to as “folie a plusiers” or the “madness of many.” The most obvious example of this is what happens in a cult, if the leader is living with a mental illness and transfers their delusions to the group. In a larger group setting, this might also be termed mass hysteria.

The symptoms of shared psychotic disorder will vary depending on the specific diagnosis of the primary person with the disorder. However, there are some features of the disorder that will be similar across cases.

Secondary Effects

Living with delusions can have effects on the physical health of both persons with the disorder due to increased stress (e.g., elevatedcortisol levels).

Secondary mental health issues may develop such as anxiety and depression due to prolonged stress and fear.

Due to the nature of the psychotic illness, both individuals may not be in touch with reality and struggle with aspects of daily living.

Primary Symptoms

Neither the person with the primary mental illness nor the person who develops the same delusions has insight into the problem or awareness that what they believe is not the truth.

The secondary person will generally develop the delusions gradually over time in a way that their normal doubt or skepticism becomes reduced.

Depending on the nature of the primary illness, that individual may experiencehallucinations(seeing or hearing things that aren’t there) or delusions (believing things that are not true, even when shown evidence of that fact).

Delusions may be bizarre, non-bizarre, mood-congruent, or mood-neutral (related tobipolar disorder). Bizarre delusions are things that are physically impossible and that most people would agree could never happen, while non-bizarre delusions are things that are possible but highly improbable.

For example, a bizarre delusion might be thinking that aliens are conducting operations on you at night, while a non-bizarre delusion might be thinking that the FBI is tracking your movements.

Mood-congruent delusions match your mood (depressed or manic). For example, a person in manic state might believe that they are about to win a big sum at the casino. In contrast, a person in a depressed state might think that their relatives are going to die in a plane accident.

Below are some other examples of possible delusions:

In general, both persons will act paranoid, fearful, and suspicious of others. They will also become defensive or angry if their delusions are challenged. Those with grandiose delusions might appear euphoric.

The primary person in the relationship will not recognize that they are making the other person ill. Instead, they think that they are simply showing them the truth, because they have no insight into their own mental illness.

In terms of the secondary person, that person may exhibit dependent personality traits, in the form of fear and needing reassurance. These individuals are often susceptible to mental illness themselves in terms of having relatives with diagnosed illnesses.

Common dyads include husband-wife (married or common-law), mother-daughter, sister-sister, or parent-child.

What causes a secondary person to take on the delusions of someone with a psychotic or delusional disorder? There are several possible risk factors including the following:

How is shared psychotic disorder diagnosed? When it first appeared in theDiagnostic and Statistical Manual of Mental Disorders(DSM-III) it was diagnosed as “shared paranoid disorder.”

Then, in the DSM-IV, it was diagnosed as “shared psychotic disorder.” Finally, in the most recent DSM-5, it is no longer identified as a separate diagnosis; rather, it is diagnosed under Section 298.9: Other specific schizophrenia spectrum and other psychotic disorder. The specific description is given below:

Finally, in theInternational Classification of Diseases(ICD-11), this illness is diagnosed as induced delusional disorder.

Overall, this disorder tends to go undiagnosed or is missed, because neither person generally has insight into their mental illness. Typically, the cases will only come to light if the primary person acts out on a delusion, which draws attention to the situation. For example, a person with a paranoid delusion about a neighbor might commit an assault.

However, even if the primary person presents for treatment, treatment providers may not be aware that there is a secondary person who is affected. For this reason, these types of cases may go undiscovered for a long time.

Finally, the steps in a diagnosis involve the following:

Finally, how is shared psychotic disorder treated? Since this disorder often goes undiagnosed, it is often just the primary person who receives treatment for their mental disorder. However, once the secondary person is identified, a team approach is required that may be composed of various professionals such as a doctor, nurse, pharmacist, mental health professionals, etc.

Since the disorder is rare, there is no standard treatment protocol. However, it is typical that the secondary person will be separated from the primary person as a first measure. Typically, this seems to help reduce the delusions in the secondary person.

Specific treatments that may be offered include the following:

Unfortunately, due to the nature of shared psychotic disorder, most people will require professional help and will not be able to overcome these issues on their own. However, if you are a person recovering from this illness, there are some things to keep in mind:

A Word From Verywell

If you suspect that you or someone you know is living with shared psychotic disorder, it might be hard to disengage from the situation to decide what is the truth versus what is delusions. In this case, it’s best to reach out for help if you can, particularly if you are the secondary person in the relationship and struggle with feeling dependent on the primary person.

When left untreated for long periods of time, shared psychotic disorder is unlikely to improve and instead may lead to chronic stress and long-term effects on the physical and mental health of you and your loved ones.

If you are the primary person in a situation involving shared psychotic disorder and you are receiving treatment from a professional, it is important to be forthcoming about the impact of your illness on those around you. Because this disorder is often missed or not detected, unless you share the details of your situation and how others are involved, it’s unlikely that the secondary person will receive help.

The bottom line is that it can be very scary and unsettling to live with delusions; however, the only way to improve the situation is to reach out for help, start regaining social ties outside the narrow relationship that has developed, and receive therapy and/or medication as needed. It is only when these steps have been taken that you are likely to see improvement in your situation.

In particular, if the secondary person is a child or dependent and cannot reach out for help themselves, it is important that others step in and recognize the situation so that aid can be provided.

1 Source

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Al Saif F, Al Khalili Y. Shared Psychotic Disorder. In: StatPearls. Treasure Island, FL: StatPearls Publishing; 2020.

American Psychiatric Association.Diagnostic and Statistical Manual of Mental Disorders.5th ed. Washington D.C.: 2013.

Guivarch J, Piercecchi-Marti MD, Poinso F. Folie à deux and homicide: Literature review and study of a complex clinical case.Int J Law Psychiatry.2018;61:30-39.

Mouchet-Mages S, Gourevitch R, Loo H. Folie a deux. Update of an old concept regarding two cases.Encephale. 2008;34:31-37.

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