Case Reports

She’s Not My Mother: A 24-Year-Old Man With Capgras Delusion

This uncommon delusion is associated with varied psychiatric, medical, iatrogenic, and neurologic conditions and may be difficult to fully resolve.

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Many patients admitted to inpatient psychiatric hospitals present with delusions; however, the Capgras delusion is a rare type that often appears as a sequela of certain medical and neurologic conditions.1 The Capgras delusion is a condition in which a person believes that either an individual or a group of people has been replaced by doubles or imposters.

In 1923, French psychiatrist Joseph Capgras first described the delusion. He and Jean Reboul-Lachaux coauthored a paper on a 53-year-old woman. The patient was a paranoid megalomaniac who “transformed everyone in her entourage, even those closest to her, such as her husband and daughter, into various and numerous doubles.”2 She believed she was famous, wealthy, and of royal lineage. Although 3 of her children had died, she believed that they were abducted, and that her only surviving child was replaced by a look-alike.2,3 Although the prevalence of such delusions in the general population has not been fully studied, a psychiatric hospital in Turkey found a 1.3% prevalence (1.8% women and 0.9% men) in 920 admissions over 5 years.4

The Capgras delusion is one of many delusions related to the misidentification of people, places, or objects; these delusions collectively are known as delusional misidentification syndrome (DMS).5,6 The Fregoli delusion involves the belief that several different people are the same person in disguise. Intermetamorphosis is the belief that an individual has been transformed internally and externally to another person. Subjective doubles is the belief that a doppelganger of the afflicted person exists, living and functioning independently in the world. Reduplicative paramnesia is the belief that a person, place, or object has been duplicated. A rarer example of DMS is the Cotard delusion, which is the belief that the patient himself or herself is dead, putrefying, exsanguinating, or lacking internal organs.

The most common of the DMS is the Capgras delusion. One common presentation of Capgras delusion involves the spouse of the patient, who believes that an imposter of the same sex as their spouse has taken over his or her body. Rarer delusions are those in which a person misidentifies him or herself as the imposter.3,5,6

Case Presentation

This case involved a 24-year-old male veteran who had received a wide range of mental health diagnoses in the past, including major depressive disorder (MDD) with psychotic features, generalized anxiety disorder, cannabis use disorder, adjustment disorder, and borderline personality disorder. He also had a medical history related to a motor vehicle accident with subsequent intestinal rupture and colostomy placement that had occurred a year and a half prior to presentation. He had no history of brain trauma.

The patient voluntarily presented to the hospital for increased suicidal thoughts and was admitted voluntarily for stabilization and self-harm prevention. He stated that “I feel everything is unreal. I feel suicidal and guilt” and endorsed a plan to either walk into traffic or shoot himself in the head due to increasingly distressing thoughts and memories. According to the patient, he had reported to the police that he raped his ex-girlfriend a year previously, although she denied the claim to the police.

The patient further disclosed that he did not believe his mother was real. “Last year my sister told me it was not 2016, but it was 2022,” he said. “She told me that I have hurt my mother with a padlock—that you could no longer identify her face. I don’t remember having done this. I have lived with her since that time, so I don’t think it’s really [my mother].” He believed that his mother was replaced by “government employees” who were sent to elicit confessions for his behavior while in the military. He expressed guilt over several actions he had performed while in military service, such as punching a wall during boot camp, stealing “soak-up” pads, and napping during work hours. His mother was contacted by a staff psychiatrist in the inpatient unit and denied that any assault had taken place.

The patient’s psychiatric review of systems was positive for visual hallucinations (specifically “blurs” next to his bed in the morning that disappeared as he tried to touch them), depressed mood, anxiety, hopelessness, and insomnia. Pertinent negatives of the review of systems included a denial of manic symptoms and auditory hallucinations. For additional details of his past psychiatric history, the patient admitted that his motor vehicle accident, intestinal rupture, and colostomy were the result of his 1 suicide attempt a year and a half prior after a verbal dispute with the same ex-girlfriend that he believed he had raped. After undergoing extensive medical and surgical treatment, he began seeing an outpatient psychiatrist as well as attending substance use counseling to curtail his marijuana use. He was prescribed a combination of duloxetine and risperidone as an outpatient, which he was taking with intermittent adherence.

Regarding substance use, the patient admitted to using marijuana regularly in the past but quit completely 1 month prior and denied any other drug use or alcohol use. He reported a family history of a sister who was undergoing treatment for bipolar disorder. In his social history, the patient disclosed that he was raised by both parents and described a good childhood with a life absent of abuse in any form. He was single with no children. Although he was unemployed, he lived off the funds from an insurance settlement from his motor vehicle accident. He was living in a trailer with his brother and mother. He also denied having access to firearms.

The patient was overweight, neatly groomed, had good eye contact, and was calm and cooperative. He seemed anxious as evidenced by his continuous shaking of his feet; although speech was normal in rate and tone. He reported his mood as “depressed and anxious” with congruent and tearful affect. His thought process was concrete, although his thought content contained delusions, suicidal ideation, and paranoia. He denied any homicidal thoughts or thoughts of harming others. He did not present with any auditory or visual hallucinations. Insight and judgment were poor. The mental status examination revealed no notable deficits in cognition.

The patient’s differential diagnosis included schizophreniform disorder, exacerbation of MDD with psychotic features, and the psychotic component of cannabis use disorder. His outpatient risperidone and duloxetine were not restarted. Aripiprazole 15 mg daily was prescribed for his delusions, paranoia, and visual hallucinations. The patient also received a prescription for hydroxyzine 50 mg every 6 hours as needed for anxiety.

Because of the nature of his delusions, comorbid medical and neurologic conditions were considered. Neurology consultation recommended a noncontrast head computer tomography (CT) scan and an electroencephalogram (EEG). Laboratory workup included HIV antibody, thyroid panel, chemistry panel, complete blood count, hepatitis B serum antigen, urine drug screen, hepatitis C virus, and rapid plasma reagin. All laboratory results were benign and unremarkable, and the urine drug screen was negative. The noncontrast CT revealed no acute findings, and the EEG revealed no recorded epileptiform abnormalities or seizures.

Throughout his hospital course, the patient remained cooperative with treatment. Three days into the hospitalization, he stated that he believed the entire family had been replaced by imposters. He began to distrust members of his family and was reticent to communicate with them when they attempted to contact him. He also experienced fragmented sleep during his hospital stay, and trazodone 50 mg at bedtime was added.

After aripiprazole was increased to 20 mg daily on hospital day 2 and then to 30 mg daily on hospital day 3 due to the patient’s delusions, he began to doubt the validity of his beliefs. After showing gradual improvement over 6 days, the patient reported that he no longer believed that those memories were real. His sleep, depressed mood, anxiety, and paranoia had markedly improved toward the end of the hospitalization and suicidal ideation/intent resolved. The patient was discharged home to his mother and brother after 6 days of hospitalization with aripiprazole 30 mg daily and trazodone 50 mg at bedtime.

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