Shared Delusional Disorder: When Beliefs Become Contagious

Shared delusional disorder, sometimes referred to as folie à deux, is an unusual mental health condition in which two or more people come to share the same false beliefs.
One person is typically the dominant party who influences the others to accept their delusions as reality.
While the prevalence of the disorder is low, the consequences of untreated symptoms can be severe both for the afflicted individuals and the people around them.

In our guide, we will review the most common causes and symptoms of shared delusions, explain the short-term and long-term risks of this disorder,
provide effective treatment and prevention strategies, and answer the most frequently asked questions on the subject to help you recognize the signs of the disorder and seek professional help.

What Is Shared Delusional Disorder?

Shared delusional disorder (SDD) is a mental illness characterized by the transfer of false beliefs from one person to another.
The term “folie à deux”—“the madness of two”—was introduced by a French psychiatrist, Charles Lasègue, in the 19th century to describe this rare phenomenon.

In most cases, shared delusions occur within a close interpersonal relationship when one individual asserts their false beliefs and eventually convinces the other person to adopt these beliefs as their own.
The disorder is usually temporary—once the people affected are separated and receive adequate treatment, their mental health improves.

What Causes Shared Delusional Disorder

There is no single explanation behind shared delusional disorder—several factors may contribute to its development:

• Personal connection. The disorder is most commonly diagnosed in family members and friends who have a close bond with one another, which makes the transfer of delusions easier.
• Psychological predisposition. If a person has a history of mental illness—for instance, they were diagnosed with schizophrenia or depression in the past—they may be more susceptible to believing delusions.
• Stressful environment. External pressure, such as poor living conditions and social isolation, may exacerbate the symptoms of shared delusions.

What Are the Symptoms of Shared Delusional Disorder

Here are the signs of shared delusional disorder you should be on the lookout for:

• Irrational beliefs. The person rejects the evidence presented to them and chooses to believe what is not real. For example, they may be convinced they are seriously ill despite the doctor’s assurances to the contrary.
• Defensive behavior. When a person is confronted about their delusions, they may become agitated, avoid conversations on the subject, and cut off the people who challenge their beliefs.
• Emotional distress. The individual struggles to concentrate, feels anxious when their beliefs are questioned or dismissed, and displays symptoms of depression such as appetite loss and insomnia.

How to Diagnose Shared Delusional Disorder

If you have spotted the symptoms of SDD in yourself or a person close to you, your first step should be to reach out to a mental health professional.
A therapist or a psychologist is qualified to diagnose the disorder.

The healthcare provider will interview the patient, learn more about their medical history, and possibly run a few tests to understand the condition of the individual.
In case the unique living circumstances of the person have led to the development of shared delusions, it may be necessary to adjust their environment and separate them from the individual who has influenced their beliefs.

How to Treat Shared Delusional Disorder

Fortunately, with proper therapy, shared delusional disorder can be treated.
Here are a few treatment options you can discuss with the mental health provider:

• Therapy. Several types of psychotherapy may be suitable for the patient: cognitive behavioral therapy to change the thinking patterns of the individual, family therapy to involve the closest friends and relatives in the treatment process, and exposure therapy to help the person slowly return to normal life.
• Medication. A psychiatrist may prescribe antipsychotic and antidepressant drugs to the patient to treat their anxiety and help them cope with the symptoms of the disorder. Make sure the person adheres to the medication schedule and reports any side effects they experience to their doctor.
• Separation. While it may be difficult to distance yourself from the person you are close to, in many cases, temporary separation is beneficial for the patient—this will allow them to remove themselves from the toxic environment and restore their mental health.

FAQs

Reach Out to Treat Mental Health for Help

Whether you are concerned for yourself or a loved one who started exhibiting symptoms of shared delusional disorder, it is crucial to address this issue as soon as possible.
Shared delusions can negatively affect a person’s life and lead to irreparable consequences if the disorder is not diagnosed and treated.

Get in touch with Treat Mental Health to talk to a certified professional—our therapists will design a personalized treatment plan for you and guide you on your path to recovery.