Learning Objectives

After the webinar, clinicians should:

1. Recognize the symptoms of delusional misidentification syndromes

2. Know the risks associated with untreated delusional misidentification syndromes

3. Understand treatment options for these syndromes

4. Summarize some of the current research findings in psychiatric treatment

[Transcript edited for clarity]

Hello, everyone. Today, I will be speaking about delusional misidentification syndromes in this Carlat webinar. My name is Victoria Hendrick. I'm a clinical professor in the Department of Psychiatry at UCLA Medical Center, and I'm also the Editor-in-Chief of The Carlat Hospital Psychiatry Report. I have no conflicts or disclosures.

Case Example

I'll begin with a case from about a year ago. The patient was a 30-year-old male with schizophrenia, disorganized type. His mother came to visit the unit, but he refused to meet with her. He told our staff that the woman looked and sounded like his mother but was actually an imposter. When his mother visited again a couple of days later, he demanded that staff not allow her on the unit, stating that she was trying to trick him and that he didn't want her visiting anymore. This case exemplifies a delusional misidentification syndrome that I will discuss in this presentation.

Facts of the case
•Your new patient is a 30-year-old male with schizophrenia, disorganized type. 

•His mother comes to the unit to visit, but he refuses to meet with her. 

•He tells staff that the woman looks and sounds like his mother but is an impostor. 

•His mother visits again two days later, and he demands that staff not allow her on the unit saying, “That lady is trying to trick me, but I don’t know who she is, and I don’t want her visiting anymore!”

Delusional Misidentification Syndromes

First, let me explain that delusional misidentification syndromes (DMS) are a type of psychotic phenomenon. Patients with DMS have a mistaken belief that a familiar person or object has been replaced or transformed. While ICD-11 has a separate diagnostic code (MB 26 0 B) for misidentification delusion, in DSM-5, they are considered delusional disorders of unspecified type (Pietkiewicz IJ et al, Clin Schizophr Relat Psychoses, 2022;16(2)). The most common form of delusional misidentification is Capgras syndrome.

•The International Classification of Diseases (ICD-11) recognizes misidentification delusion as a distinct diagnostic code, specifically MB26.0B. 

•In the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR), these syndromes are classified as delusional disorders of unspecified type.

Capgras Syndrome

Capgras syndrome, named after the French physician Joseph Capgras, is characterized by the belief that loved ones have been replaced by identical-looking imposters. It is mostly observed in patients with psychotic illnesses, with about 56% of cases occurring in individuals with conditions such as schizophrenia. However, dementia, delirium, traumatic brain injuries, and other medical conditions account for a significant proportion, approximately 43% (Pandis C et al, Psychopathology 2019;52(3):161-173). These conditions have always fascinated me during my work on the psychiatric unit.

Patients with Capgras syndrome are typically younger and predominantly female when the underlying illness is a psychiatric disorder. In cases where the underlying illness is dementia, delirium, or another medical condition, patients tend to be older, and the imposter is usually the spouse or an inanimate object.

•Most commonly observed in individuals with psychiatric illnesses, particularly schizophrenia (56% of cases), but can also occur in dementia, delirium, and other medical conditions (43% of cases). 

Capgras Syndrome Variants

There are some variants of Capgras syndrome. One condition is called subjective doubles, where patients believe that doppelgangers or doubles of themselves exist and act independently. Another variant is reverse Capgras, where patients believe they have been replaced by an imposter, often a famous person (Kim E, Case Rep Psychiatry 2022;20; 2022:9703482).

Variants of Capgras

• Subjective doubles
• Reverse Capgras

Fregoli Syndrome and Variants

Another fairly common syndrome is Fregoli syndrome. Patients with Fregoli syndrome believe that a familiar person is repeatedly changing their appearance, for example, that a stranger is actually a familiar person in disguise. This condition is named after Leopoldo Fregoli, an Italian vaudeville actor famous for his rapid costume and character changes, creating the illusion of multiple identical individuals (Klein CA and Hirachan S, J Am Acad Psychiatry Law 2014;42(3):369-378).

Another variant is intermetamorphosis, where individuals believe that familiar people and strangers swap identities while maintaining their original appearances. I had a patient with Fregoli syndrome, a young woman on my inpatient unit, who kept insisting that I was really her aunt. That was an example of Fregoli syndrome.

Other Delusional Misidentification Syndromes

There are several other delusional misidentification syndromes, although they are less common. Over the years, I have encountered some of these on the hospital inpatient unit. The Truman Show Delusion, named after the 1998 movie, is the belief that one's entire life is a staged reality show broadcast for others' entertainment. Cotard syndrome is the belief that one is dead or that parts of their body are missing or petrified. I once had a patient who insisted that all his organs had been removed.

Another syndrome is clinical lycanthropy, the belief that one is turning into or has already turned into an animal, such as a wolf. Symptoms include claims of growing longer teeth, developing hair throughout the body, walking on all fours, and making growling or howling sounds.

Don't Confuse With Face Blindness

It's essential not to confuse these syndromes with face blindness. For example, with Fregoli syndrome, it's crucial to rule out prosopagnosia, which is a common condition known as face blindness.

Prosopagnosia impairs the ability to recognize familiar faces, even one's own, while leaving other aspects of visual processing and intellectual functioning intact. Its prevalence is estimated at about 2.5%, but getting an exact estimate is challenging (Kennerknecht I et al, Am J Med Genet A 2006;140A(15):1617-1622). Brad Pitt famously revealed about a year ago that he suffers from prosopagnosia.

Note

• It's important to differentiate these syndromes from each other and from face blindness (prosopagnosia), a condition impairing the ability to recognize familiar faces.

Prevalence of DMS

What is the prevalence of delusional misidentification syndromes? Capgras syndrome is the most frequent presentation, followed by Fregoli syndrome. Approximately 14% of patients with psychiatric diagnoses experience Capgras syndrome. The risk is highest among individuals with schizophrenia and dementia (Salvatore P et al, Psychopathology 2014;47(4):261-269; Klein CA and Hirachan, J Am Acad Psychiatry Law 2014;42(3)369-378).

What Causes DMS?

The pathology of these syndromes is not well understood, although right-sided frontal brain lesions are frequently observed in patients who undergo brain imaging. There is also evidence suggesting a genetic vulnerability contributing to the risk (Teixeira-Dias M et al, J Neuropsychiatry Clin Neurosci 2023;35:171-177).

Assessment and Management

As with any unusual presentation of psychosis, it is crucial to conduct a standard workup to rule out medical or neurological causes. However, in most cases, the underlying issue will be a primary psychotic disorder. Additionally, be sure to inquire about any thoughts of harming others.

Risk of Violence and Self-Harm

Approximately 60% of patients with delusional misidentification syndromes have physically attacked someone in relation to the misidentification. Anger and delusions involving persecution, spying, and conspiracy are associated with violence. Cotard syndrome, where the individual believes they are dead or missing body parts, is associated with an elevated risk of suicide (Silva JA et al, Psychopathology 1994;27(3-5):215–219; Bott N et al, Front Psychol 2016;7:1351).

Treatment

Clozapine has shown particular effectiveness, even when the underlying etiology appears to be neurological. Remission rates between 60 to 70% have been reported. In my experience, most patients I've treated have generally improved, aligning with the optimistic rate of remission. Antidepressants or mood stabilizers may be used if there is an underlying depression or bipolar disorder. Electroconvulsive therapy (ECT) and cognitive-behavioral therapy (CBT) have shown success in some cases that are refractory to antipsychotics. However, many patients' delusions remain fixed.

Summary

Delusional misidentification syndromes are a type of psychotic phenomenon typically associated with schizophrenia, bipolar disorder, and sometimes dementia. Patients with these syndromes have a mistaken belief that a familiar person or object has been replaced or transformed. Capgras syndrome is the most common form, followed by Fregoli syndrome.

Treatment involves the use of antipsychotic medications, with clozapine showing effectiveness. Medical and neurological causes should be ruled out during the assessment, and the risk of violence and self-harm should be assessed. If antipsychotic medications are ineffective, ECT and CBT can be considered as alternative or additional treatments. It's important to note that not all patients will experience complete remission, and delusions may persist despite multiple trials of medications and interventions.    

References
Pietkiewicz IJ et al, Clin Schizophr Relat Psychoses, 2022;16(2)[pdf]
Pandis C et al, Psychopathology 2019;52(3):161-173
Kim E, Case Rep Psychiatry 2022;20; 2022:9703482
Klein CA and Hirachan S, J Am Acad Psychiatry Law 2014;42(3):369-378
Kennerknecht I et al, Am J Med Genet A 2006;140A(15):1617-1622
Salvatore P et al, Psychopathology 2014;47(4):261-269
Teixeira-Dias M et al, J Neuropsychiatry Clin Neurosci 2023; 35: 171-177
Silva JA et al, Psychopathology 1994;27(3-5):215–219
Bott N et al, Front Psychol 2016 ;7:1351

Earn credit for watching our webinars with a Webinar CME Subscription.
For more on this topic, see Who's Who? A Review of Delusional Misidentification Syndromes, by Adrienne Grzenda, MD, PhD. Featured in The Carlat Hospital Psychiatry Report.

Click to download the slides

__________

The Carlat CME Institute is accredited by the ACCME to provide continuing medical education for physicians. Carlat CME Institute maintains responsibility for this program and its content. Carlat CME Institute designates this enduring material educational activity for a maximum of one-half (.5) AMA PRA Category 1 Credits^TM. Physicians or psychologists should claim credit commensurate only with the extent of their participation in the activity.