Shared psychotic disorder is a rare condition in which two or more people who are in a relationship share a delusion. The condition is treated on a case-by-case basis, and medication and/or talk therapy can be beneficial for treating it [1].

What is shared psychotic disorder?

Shared psychotic disorder, also called folie á deux, shared psychosis, or shared delusional disorder, is a psychiatric disorder that occurs when two or more people in a close relationship share the same delusion. It develops when a person with a psychotic or delusional disorder (called the primary) has a delusion and convinces one or more other people (the secondary) that the delusional belief is true [1].

This condition most often occurs between two people, but sometimes it can be seen among larger groups. The condition was specifically listed in the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM). In the present fifth edition (DSM 5), it has been removed but falls under the category of “other specified schizophrenia spectrum and other psychotic disorders” [1].

Symptoms of shared psychotic disorder

The following symptoms are indicative of shared psychotic disorder [1]:

  • Two or more people share the same delusion
  • Each person has a false, fixed belief that they maintain, despite the belief being unrealistic
  • Evidence of anger or defensiveness when the delusion is challenged
  • Irritability if the delusion involves paranoia
  • Euphoria if the delusion is grandiose
  • Paranoia, fear, or suspicion toward neighbors or people in the community

Causes of shared psychotic disorder

Experts do not know the exact cause of shared psychotic disorder, because it is rarely seen in clinical practice, but there are certain factors that can increase the risk of developing this condition. The following risk factors are linked to shared psychotic disorder [1]:

  • Having a long relationship/close attachment with the “primary” who experiences a psychotic disorder
  • Being married to a person with psychotic disorder, or being the sister of such a person
  • Social isolation
  • Having an underlying personality disorder
  • Untreated mental illness, mostly commonly delusional disorder or schizophrenia, in the “primary”
  • Cognitive impairment, intellectual disability, dementia, depression, or another mental illness in the “secondary”
  • Life stressors that lead the “secondary” to simply accept the delusion, because they are too distressed to fight against it
  • Communication problems in a relationship

Diagnosing shared psychotic disorder

The DSM no longer includes shared psychotic disorder in its current edition. Previously, shared psychotic disorder was diagnosed when one person developed a delusion in the context of a relationship with another person who already had the delusion. To be diagnosed, the content of the delusion in the secondary had to be similar to the content of the delusion experienced by the person with the existing false beliefs. [2].

In the current DSM, shared psychotic disorder falls under the category of other specified schizophrenia spectrum and other psychotic disorders. This condition is diagnosed when a person has symptoms of a psychotic disorder that do not meet criteria for another disorder, such a schizophrenia, but they are severe enough to cause significant distress and difficulties with life functioning. A clinician making this diagnosis lists a reason for the diagnosis, which could include, sharing delusions with an individual with psychosis [2].

To make such a diagnosis, a clinician may perform a urine drug screen to rule out substance-related causes of shared psychotic disorder. They may also request a medical examination to rule out organic causes of delusions. If the delusions are not a result of a medical or substance-related cause, a clinician will conduct a psychiatric assessment. It is helpful if a clinician can speak to other family members about the history and content of the delusions, as the primary who is the partner of the person with shared psychotic disorder is likely to be fixated on the delusion [1].

Prevention of shared psychotic disorder

There is no guaranteed method for preventing shared psychotic disorder; rather, it can be managed with early recognition and treatment to reduce the risk of complications. If the partner or sibling of someone with a psychotic disorder like schizophrenia begins to show signs of delusions, they may be developing a shared psychotic disorder. In this case, early evaluation and intervention with a mental health provider can treat the condition in its early stages and reduce its severity.

Treatment for shared psychotic disorder

Treatment for shared psychotic disorder occurs on a case-by-case basis, with treatment tailored to the needs of each unique patient. Some experts suggest that the secondary should be separated from the primary, but there is also evidence that this may aggravate the condition further [1].

Oftentimes, treatment for both people involved in the shared psychotic disorder is necessary. Both partners may benefit from taking medications. They may also participate in talk therapy, either alone or as a couple [1].

Talk therapy and medication for shared psychotic disorder are discussed below in further detail.

Therapy

There is relatively little research available that explores therapeutic treatments designed specifically for the treatment of shared psychotic disorder, so most of what is known about treating the condition comes from studies with other psychotic disorders, such as schizophrenia.

Some of the following therapeutic methods are beneficial for treating psychotic disorders [3]:

  • Cognitive Behavioral Therapy: This therapy method helps people to evaluate the logic of their thoughts by asking them to identify evidence that their thoughts are valid. The ultimate goal is to help people replace distorted or distressing thinking patterns with healthier, more adaptive ways of thinking.
  • Skills Training: This intervention is often delivered in a group therapy setting. The goal is to train individuals with psychotic disorders on social skills, such as making conversation, establishing friendships, and solving problems [4].
  • Assertive Community Treatment: Assertive community treatment focuses on providing clients with holistic treatment within community settings, rather than having all of their treatment occur at a clinic. Patients receiving assertive community treatment receive a variety of services, including medication, housing assistance, financial skills training, psychoeducation, and assistance with accessing services like public transportation [5].
  • Supported Employment: Supported employment interventions teach job-training skills to individuals who live with a mental illness, like shared psychotic disorder, which can make it difficult for people to maintain employment.
  • Family-Based Services: Extended family members can be useful in the treatment of shared psychotic disorder. Family therapy and interventions can teach loved ones about the delusional symptoms of shared psychotic disorder and help them to develop skills for supporting the person with the mental health disorder.

Medication

There are three types of medication that are commonly used to treat shared psychotic disorder: antipsychotics, antidepressants, and mood stabilizers. These medications are described in more detail below:

  • Antipsychotics: These medications block dopamine receptors in the brain, as too much dopamine can lead to psychotic symptoms like hallucinations and delusions. This class of drugs includes but is not limited to risperidone, olanzapine, quetiapine, ziprasidone, aripiprazole, and haloperidol [6].
  • Antidepressants: A common class of antidepressants called selective serotonin reuptake inhibitors (SSRIs) may be used to treat shared psychotic disorder, since depression is a risk factor for developing this condition. Some medications under this category are fluoxetine, sertraline, citalopram, escitalopram, paroxetine, and fluvoxamine [6].
  • Mood Stabilizers: This class of medications may also be useful for shared psychotic disorder. Lithium, valproic acid, carbamazepine, oxcarbazepine, and lamotrigine fall under this category [6].

Self-care for shared psychotic disorder

If you live with symptoms of shared psychotic disorder, it’s important to care for yourself. You can practice self-care and manage your condition by:

  • Sticking to your treatment plan
  • Participating in support groups
  • Connecting with resources in the community

FAQs about shared psychosis

How common is shared psychosis?

It is difficult to determine the exact prevalence of simultaneous psychosis, because it may go unrecognized and therefore not be diagnosed. Prevalence estimates suggest that 1.7% to 2.6% of psychiatric hospital admissions are a result of shared psychotic disorder [1].

What can happen if shared psychotic disorder is left untreated?

Left untreated, simultaneous psychosis can lead to complications. For instance, people with paranoid delusions may act out aggressively toward others or even commit acts of assault in an attempt at what they perceive as self-defense. In some cases, paranoid or religious delusions can become dangerous to the person with the shared psychotic disorder, or to others. This is why seeking treatment and staying committed to a treatment plan are essential.

Resources:

  1. Al Saif, F., & Al Khalili, Y. (2022). Shared psychotic disorder. National Library of Medicine. Retrieved October 23, 2022, from https://www.ncbi.nlm.nih.gov/books/NBK541211/.
  2. Substance Abuse and Mental Health Services Administration. (2016). DSM-IV to DSM-5 psychotic disorders. National Library of Medicine. Retrieved October 24, 2022, from https://www.ncbi.nlm.nih.gov/books/NBK519704/table/ch3.t20/
  3. Ellenberg, S., Lynn, S. J., & Strauss, G. P. (2018). Psychotherapy for schizophrenia-spectrum disorders. In D. David, S. J. Lynn, & G. H. Montgomery (Eds.), Evidence-based psychotherapy: The state of the science and practice (pp. 363–405). Wiley Blackwell. https://doi.org/10.1002/9781119462996.ch14
  4. Ntoutsia, P., Katsamagkos, A., & Economou, M. (2013). The efficacy of social skills training for individuals with schizophrenia. Psychology: The Journal of the Hellenic Psychological Society, 20(1), 34–53.
  5. Bond, G.R., & Drake, R.E. (2015). The critical ingredients of assertive community treatment. World Psychiatry, 14(2), 240-242. doi: 10.1002/wps.20234
  6. Wy, T.J.P., & Saadabadi, A. (2022). Schizoaffective disorder. National Library of Medicine. Retrieved October 24, 2022 from https://www.ncbi.nlm.nih.gov/books/NBK541012/