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  • Ajay Macherla

Understanding the Capgras Delusion




Abstract

Capgras Delusion is a type of psychotic disorder characterized by the belief that a patient’s close friends and family members have been replaced by identical imposters. This delusion can lead patients to paranoia, depression, and substance abuse as a tool to cope for the “loss” of a loved one. The condition is rare and unclear, especially regarding the etiology and neuropathology. This literature review aims to synthesize five studies on Capgras Delusion using a retrospective, qualitative analysis in order to shed light on the mysteries of the disorder.


The five studies included Mazzone et al. (2012), Shlykov et al. (2016), Aziz and Rodgers (2019), Bell et al. (2017), and Pandis et al. (2019). Two were meta-analytical studies and three were case studies examining the effectiveness of electroconvulsive therapy (ECT) and antipsychotic medication (APM) on patients with the delusional disorder.


The literature seems to suggest that a combination of APM and ECT is most effective in treating patients with the delusion. In the case studies, a similar treatment intervention was present in the target patients, and they received tremendous results after taking the treatment plan. Furthermore, Capgras Delusion can affect individuals of all ages, as seen in Mazzone et al. (2012), who dealt with a 11-year old patient. However, APM and ECT still prove to be effective in treating younger populations. The meta-analytical studies indicate that the delusion is far more ambiguous than originally thought. Symptoms vary from individual to individual, and some studies even found no evidence of neural damage in the right hemisphere of the brain, whereas other studies did find such evidence. One study proposes that there could be a functional etiology to Capgras Delusion, perhaps triggered from a traumatic event experienced by the patient.


From the investigation, it was concluded that researchers must first gain a better understanding of this condition by identifying an etiology to the disease. This would require a sample of Capgras Delusion patients and neuroimaging in order to determine whether there are correlations in damage in certain regions of the brain. Localizing the condition to a specific brain region will streamline efforts towards identifying a pathological mechanism by which the condition creates the delusion in the patient and triggers common symptoms of Capgras Syndrome.


 

Introduction


The realm of delusional disorders are generally characterized as a type of mental illness, or psychosis, in which the line between imagination and reality is distorted. Patients with delusional disorders do not necessarily have bizarre or otherworldly delusions; rather, they are grounded in the logic of real life (Delusional Disorder, 2018). On a high level, delusional disorders are extremely rare and are, for the most part, caused by traumatic events.


Within this area of disease, the Capgras Delusion is a type of delusional disorder in which affected patients believe that a close family member or friend has been replaced by an imposter. This delusion can lead to social withdrawal and a lack of trust for those around patients with this condition, amongst other symptoms. Other symptoms associated with the disease include severe depression, anxiety, and substance abuse (Sampathi et al., 2018).


Recent empirical studies have suggested that the condition is a comorbidity in conjunction with other neurological or neurodegenerative diseases (Salvatore et al., 2014). Particularly, the syndrome was most prevalent in first-episode psychotic disorders, meaning that it is the first time the patient is experiencing delusional or psychotic symptoms after a traumatic event.


Although there is no definitive cure to the disease, some studies have suggested that electroconvulsive therapy (ECT), mood-stabilizing drugs (MSD), and antipsychotic drugs (APD) have controlled the condition to some extent. One particular study noticed a significant impact of the therapies and drugs on a sample of young women with Capgras Delusion (Rapinesi et al., 2015).


There is still more information to be uncovered in the investigation of this disease, which is why empirical evidence, along with literature reviews, are necessary to streamline research efforts toward finding more effective solutions to this delusion. The aim of this literature review is to synthesize current knowledge on the Capgras Delusion and provide recommendations on how future research should be conducted so as to reveal valuable results.

 

Disease Overview

In this literature review, we would like to provide a brief overview of the Capgras Delusion. We will summarize the disease in a seven-step overview framework: etiology, pathology, prognosis, diagnosis, symptoms, treatments, and epidemiology.


Etiology:

Although the etiology of the delusion is unclear, multiple theories have been proposed as to the cause of this condition. An article cites that seizure disorders have an “8-fold increased risk of developing psychosis, with an overall prevalence of about 6%” (Pelak, 2019). From this information, it is clear that perhaps psychotic or seizure disorders have specific pathologies that may lead to the development of this disease.


One review notes that irritative and inflammatory sensations on the cortical centers of the brain may cause impairments in understanding complex information, which may lead to the delusion that a loved one has been replaced by an imposter (Manford, 1998). A notable symptom of this condition is visual hallucinations.


Pathology:

Similarly, the neuropathology of the Capgras Delusion is unclear and calls for more research. A literature review proposes that perhaps neuro-ophthalmologic dysfunction may cause visual hallucinations and impairments in judgment of loved ones. There could also be damage to the primary visual cortex in the occipital lobe of the brain or other visual cortical areas in the temporal lobes, which all have been linked to complex visual processing. Lesions or plaques in these areas can lead to visual hallucinations and cognitive deficits (Lilly et al., 2018).


Prognosis:

Like most aspects of the Capgras Delusion, the prognosis of the disease requires more research. A study in 1978 consisted of 20 patients with this delusion and studied the course of the disease over an unspecified observation period. They noted that the first notice of the syndrome occurred at later stages of the patients’ psychosis. However, with alleviation of depressive symptoms, the researchers noticed that the delusion disappeared.

Another correlation noticed that the delusion was stronger and more persistent when there were comorbidities in the patient, such as schizophrenia (Christodoulou, 1978). Although the study gives little information on the development of the disease, it can be inferred that the condition occurs at the end of psychosis, and becomes worse over time (and especially in tandem with comorbidities). These results indicate that treatment interventions are necessary to ensure that the symptoms of the condition are not exacerbated.


Diagnosis:

According to a database review, there is currently no diagnosis criteria or standards for populations with Capgras Delusions. This lack of diagnosis information makes it difficult for physicians to both identify the condition and have enough time to initiate treatment interventions and researchers to streamline research efforts toward learning more about the delusional disorder. At the moment, clinicians typically look for the primary symptom of the delusion: the perception that a loved one has been replaced by an imposter (Bell et al., 2017).


Symptoms:

Symptoms of the Capgras Delusion include the following (Barton, 2011; Thaipisuttikul et al., 2012; Sampathi et al., 2018):

  • Delusion that a loved one or close friend has been replaced by an imposter or a double

  • Anxiety

  • Depression

  • Substance abuse

  • Dementia

  • Social withdrawal

  • Mood swings

  • Visual hallucinations

  • Prosopagnosia


Treatments:

Although there is no definitive cure to the delusion, multiple treatments have been proposed in the medical community. Two primary treatment methods include ECT and APD.

ECT is a psychiatric treatment in which brief electric currents are passed through the brain of the patient, who is under general anesthesia. These electric shocks trigger a seizure in the patient, which can cause “changes in brain chemistry” that can “reverse symptoms of certain mental health conditions” (Mayo Clinic Staff, 2018). In a case study on a 36 year-old patient who believed that her son and family were replaced by doubles, 6 ECT sessions were administered. Ultimately, the patient received positive results and the majority of the symptoms were improved (Rapinesi et al., 2015).


APD is a type of medication used to treat mental disorders characterized by a distance from the real world, or psychosis. APD is commonly used for treating schizophrenia, but it can also be used as a mood stabilizer that can decrease nihilistic delusions, such as Cotard’s Syndrome (Chokhawala & Stevens, 2020). A case study on a patient with Cotard’s Syndrome and Capgras Syndrome noted “full remission in psychotic symptoms and delusions by using clozapine in combination with valproic acid” (Orum & Kalenderoglu, 2017). Both clozapine and valproic acid are types of APD.


Epidemiology:

A study conducted in 2014 attempted to investigate the prevalence of the Capgras delusion and identify comorbidities or clinical outcomes of the condition. Through studying 517 hospitalized patients with psychosis, the study found that the 14.1% of the patients had the disease. Furthermore, there was increased risk with patients who had schizophrenia, depression, and other delusional disorders (11.4%, 15%, 11.1%), and a lower risk in those with bipolar-I and schizoaffective disorders (10.3%, 8.2%).


Bipolar-1 disorder is a type of disorder where the patient has a major psychotic or traumatic event in their life, which may cause periods of irritable moods and abnormal behaviors. Schizoaffective disorders is a term that combines both schizophrenia and other mood disorders, such as delusions, hallucinations, depression, and mania. Other risk factors included sex, age, history with abuse or trauma, and past neurological disorders. From these results, it can be seen that the delusion is rare, but can be exacerbated with certain prerequisites (Salvatore et al., 2014).

 

Methods

This paper employed a retrospective, qualitative analysis of five research studies on the etiology, pathology, comorbidities, and effectiveness of ECT and APD in Capgras Syndrome. For the research, studies from the National Center for Biotechnology Information and the PubMed search engine from the National Library of Medicine were utilized to overview the respective studies.


To control for errors and biases in the study, a discussion of the limitations of the study, along with its perceived relevance to the research investigation, will be provided. This discussion will ensure that all errors are accounted for in the exploration, and all information has value to furthering discovery in the Capgras Delusion.


To conduct this study, the following procedure was followed. First, preliminary research on the etiology, pathology, prognosis, diagnosis, symptoms, treatments, and epidemiology for the condition was conducted. These results were refined and synthesized into the seven-step disease overview framework presented previously in the disease overview section. Second, research studies on Capgras Delusion were searched for on medical search engines with the following keywords: Capgras Delusion, Neuropathology, Psychiatry, Comorbidities (Schizophrenia, First Episode Psychosis), ECT, APD, and Effectiveness.


After narrowing down the literature to focus on in the review, the next step taken was to evaluate each study and take notes on the research aim, method, results, conclusions, and strengths or limitations of the study. These notes were useful in critically evaluating each study in this paper. Finally, the results were written and synthesized before being compiled into a cohesive conclusions section for this paper.


Using these results, a conclusion on the effectiveness of treatments for Capgras Delusion, along with a discussion of the next steps in terms of research efforts, will be provided.

 


Results

Mazzone et al. (2012):

Aim: to describe the clinical approach to Capgras Syndrome, specifically in younger patients with the condition

Method:

  • Case study of an 11-year old Caucasian girls diagnosed with Capgras Syndrome

  • Showed normal learning abilities and social skills before diagnosed with the disorder, became more shy and socially withdrawn

  • Developed delusions of possibly being harmed by her parents, believed that her parents had been replaced by imposters

  • Psychological assessment was completed multiple times on the patient at the time of admission in the psychiatric unit, one months after, three months, and six months after

  • Treated with risperidone for 3mg daily, sertraline was added, 50mg per day

  • Risperidone is a type of APM, whereas sertraline is a type of serotonin reuptake inhibitor that can treat depression, OCD, PTSD, or mania

Results:

  • Evaluations indicated that the patient had improvements in psychotic symptoms from the Capgras Syndrome following treatment of the APM and serotonin reuptake inhibitor

Conclusions:

  • APM does also work in younger populations, particularly children in elementary school

  • Combination of APM and serotonin inhibitor may improve clinical outcomes than APM

Strengths:

  • Significant improvements in the patient

  • No ethical considerations

  • High reliability

  • Showed relationship between APM and serotonin reuptake inhibitor

  • Demonstrated in younger populations, lack of literature on this topic

Limitations:

  • Low sample size

  • Low generalizability to all populations

  • Did not control for other demographic factors in the study as it was a case study

Shlykov et al. (2016):

Aim: to investigate the effectiveness of APM in treating Capgras Delusion with thyroid dysfunction comorbidities

Method:

  • Case study of 65 year old woman with hypothyroidism, paranoia, and Capgras Syndrome

  • Also experienced symptoms of catatonia

  • Researchers conducted antibody tests, MRI, EEG, and other consultations

  • Treated with levothyroxine, 50 ug daily, and simvastatin, 20 mg, for increased cholesterol

  • Olanzapine was also administered for 10 mg at bedtime

Results:

  • Combination of Levothyroxine, a type of drug for hypothyroidism, and olanzapine, a type of APM, proved to be effective in treating both the patient's thyroid problems, but also their psychosis

  • Noted that “patient’s improvement was most evident after olanzapine was initiated.”

Conclusions:

  • Thyroid dysfunction may present itself as a comorbidity for Capgras Delusion

  • Combination of APM and other medication for thyroid problems does not seem to harm health, and thus can be utilized safely

Strengths:

  • Significant improvements in the patient

  • No ethical considerations

  • High reliability

Limitations:

  • Low sample size

  • Low generalizability to all populations

  • Limited in only one comorbidity

  • Does not explain whether other medications for thyroid dysfunction, other that levothyroxine, combines well with APM

  • Only considered one type of APM, olanzapine


Bell et al. (2017):

Aim: to identify cases of Capgras delusion and associated comorbidities and demographic information

Method:

  • Computer-aided data extraction and qualitative analysis of 250,000 cases from South London and Maudsley Clinical Record Interactive Search (CRIS) database

Results:

  • 84 patients with clear diagnosis of Capgras Delusion

  • Disorder was not “monothematic” in the majority of the cases identified, meaning it was not the dominating condition in the patient

  • Misidentified family members and close partners were found to be thought of as “imposters” by Capgras Delusion patients in 25% of cases

  • Noted to contradict “dual route face recognition models”

  • No evidence for right hemisphere damage using brain imaging

  • Demographically and ethnically diverse

Conclusions:

  • Capgras Delusion is more “diverse than current models assume,” both on a demographic level and on a bioinformatics level

  • Disorder may not be as predominant in patients as originally thought

  • Lack of evidence for right hemisphere damage in the brain due to the delusional disorder

Strengths:

  • Large sample size

  • Computational approach ensures reliability

  • No ethical considerations

Limitations:

  • Low generalizability

  • Low cross-cultural validity

  • More research needed for the neuroimaging data, as it may starkly contradict past literature


Pandis et al. (2019):

Aim: to review current case reports and literature on Capgras Delusion to gain a better understanding of the etiology of the condition

Method:

  • English papers published since 1923 on the topic were identified

  • Medical databases searched include Meldine, PsychINFO, Embase Classic, and Embase

Results:

  • 258 cases extracted from 175 papers

  • Capgras Delusion was associated with a variety of types of “imposters,” including instances of patients having multiple “imposters”

  • Visual and auditory hallucinations were prevalent in these cases

  • Patients typically had memory and visual-spatial impairments, right hemisphere damage, and difficulty recognizing inanimate objects

Conclusions:

  • Capgras Delusion is associated with several pathological symptoms, but it is difficult to identify an etiology from the data

  • The condition is more ambiguous than originally thought

  • Could have an organic or functional etiology

  • Organic Etiology: originating from infection, intoxication, or types of trauma

  • Functional Etiology: coming from physiological damage and other comorbidities in the body

Strengths:

  • Large sample size

  • No ethical considerations

  • High reliability

Limitations:

  • Low generalizability

  • Only considered English paper

  • No strong etiology or theory established in the paper


Aziz and Rodgers (2019):

Aim: to investigate the etiology and pathology of Capgras Delusion through a case study

Method:

  • Case study of a 69 year-old retired secretary

  • Previous history of bipolar affective disorder, atrial fibrillation, and hypertension. The latter of the two was currently being treated

  • Presented nihilistic delusions, guilt, paranoia, and depressive episodes of disturbed sleep and retardation

  • Diagnosed with Capgras Delusion in the study

  • Administered 9 sessions of ECT, along with mirtazapine and olanzapine

Results:

  • Responded well to the treatment and “has no psychotic symptoms”

  • Unable to remember her previous delusions

  • Comorbidity of schizophrenia and nihilistic delusions appear to exacerbate the syndrome, but they were nonetheless able to treat the patient

  • Arguably a relationship between Capgras Delusion and Cotard Syndrome

Conclusions:

  • Bipolar disorders, psychosis, and Cotard’s Syndrome appear to worsen Capgras Delusion, but APM and ECT are nonetheless effective in treating the patient

  • May be side effects of an inability to remember the delusions, cognitive deficits may be implied in the treatments

Strengths:

  • Significant improvements in the patient

  • No ethical considerations

  • High reliability

Limitations:

  • Low sample size

  • Low generalizability

  • Did not control for other factors (i.e. gender, race, etc.) as it was a case study

  • Unclear whether APM or ECT had a more significant effect in the treatment process

 

Discussions and Next Steps

Let us discuss the five studies outlined in the previous section. First, let us consider the effectiveness of available treatments for Capgras Delusion.


Overall, the literature suggests that ECT and APM appear to be effective in treating patients with the delusional disorder. Specifically, in case studies such as Mazzone et al. (2012), Shlykov et al. (2016), and Aziz and Rodgers (2019), APM was proven to be effective in alleviating psychotic symptoms in the target patient. However, it must be noted that there was a limited number of studies investigated in this study. More research must be conducted to ensure that these results can be generalized to the mass of literature on the effectiveness of APM on Capgras Delusion patients. Furthermore, another concern in this data selection is the limited evidence concerning specific APMs. In the three studies, only olanzapine, mirtazapine, and risperidone were tested as effective in the case studies. Other types of medications may not have similar effects as those studied in this investigation. However, the empirical evidence was able to suggest that these APMs are nonetheless effective in treating the patients regardless of other medications taken in tandem, such as sertraline (selective serotonin reuptake inhibitor) or levothyroxine (treats hypothyroidism).


A similar argument can be made for the effectiveness of ECT in treating patients with Capgras Delusion. Aziz and Rodgers (2019) was able to show that after 9 sessions of ECT, and APM, the case study patient had “no psychotic symptoms” (VM & S, 2019). A similar study outlined in the disease overview section of this investigation found that after 6 sessions of ECT, along with APM and mood-stabilizers, allowed the patient to show “rapid, permanent, and effective control of long-standing Capgras syndrome” (Rapinesi et al., 2015). One aspect of these studies to note is that they focus on ECT used in conjunction with APM. It was difficult to find literature that isolated ECT as the sole treatment intervention in a patient. More research must be conducted to this end to determine whether ECT can act as a stand-alone treatment for patients with Capgras Delusion, or whether ECT works more effectively when applied with APM.


A noteworthy aspect of the investigation is that it appears that Capgras Delusion can affect individuals of all ages, which can be most evidently seen in Mazzone et al. (2012). Even children are susceptible to this psychotic delusion, a notion that challenges the paradigm that delusions and first-episode psychotic disorders can only occur in older patients. Nonetheless of the age, the patient was still able to be treated effectively through APM.


Considering Bell et al. (2017) and Pandis et al. (2019), the studies only emphasize the notion that the scientific and medical community have already embraced so far: the Capgras Delusion is far more complex than originally thought. Through meta-analytical methods and qualitative analysis, the studies were able to associate visual and auditory hallucinations, memory and visual-spatial impairments, and prosopagnosia as potential comorbidities in patients with Capgras Delusion. The neuropathological explanation behind why these symptoms occur are still unclear, but Pandis et al. (2019) was able to hypothesize that there may be either an organic or functional etiology. Although vague at best, the study can point professionals in the right direction regarding the study of the etiology and pathology of the condition.


Interestingly, the meta-analytical studies above were able to show a demographic and ethnic diversity in patients with Capgras Delusion. This result implies that these confounding variables must be accounted for in future studies. Perhaps there are larger effects in males compared to females, or perhaps the condition occurs in particular geographical regions due to environmental factors. Further research into Capgras Delusion must consider these possibilities so as to ensure reliability and validity in their findings.


The next steps to gain a better understanding of this condition is to first identify an etiology to the disease. This would require a sample of Capgras Delusion patients and neuroimaging in order to determine whether there are correlations in damage in certain regions of the brain. Localizing the condition to a specific brain region will streamline efforts towards identifying a pathological mechanism by which the condition creates the delusion in the patient and triggers common symptoms of Capgras Syndrome.


With this understanding, scientists can re-design and revamp existing treatments, such as ECT and APM, and create more effective ones that can be distributed widely. In doing so, professionals will be able to provide effective treatment to larger populations of affected patients.

 

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