Fregoli delusion
Encyclopedia
The Fregoli delusion or the delusion of doubles is a rare disorder in which a person holds a delusion
al belief that different people are in fact a single person who changes appearance or is in disguise. The syndrome may be related to a brain lesion, and is often of a paranoid
nature with the delusional person believing themselves persecuted
by the person they believe is in disguise.
A person with the Fregoli delusion can also inaccurately replicate places, objects, and events. This disorder can be explained by "associative nodes." The associative nodes serve as a biological link of information about other people with a particular familiar face (to the patient). This means that any face that is similar to a recognizable face to the patient, the patient will recall that face as the person they know.
The Fregoli delusion is classed both as a monothematic delusion
, since it only encompasses one delusional topic, and as a delusional misidentification syndrome
, a class of delusional beliefs that involves misidentifying people, places, or objects. Like Capgras delusion
, psychiatrists believe it is related to a breakdown in normal face perception
.
who was renowned for his ability to make quick changes of appearance during his stage act.
P. Courbon and G. Fail first reported the condition in a 1927 paper (Syndrome d’illusion de Frégoli et schizophrénie). They described a 27-year-old woman who believed she was being persecuted by two actors she often saw at the theatre. She believed these people pursued her closely, taking the form of people she knew or met.
(DMS) are rooted in the inability to register the identity of something, whether it is an object, event, place or even a person. There are various forms of DMS, such as the syndrome of subjective doubles, intermetamorphosis
, Capgras syndrome and Fregoli syndrome. However, all of these various syndromes have a common denominator: they are all due to malfunctional familiarity processing during information processing. The most common syndromes are Capgras and Fregoli. Capgras syndrome is the delusional belief that a friend, family member, etc. has been replaced by a twin impostor. Fregoli syndrome is the delusional belief that different people are in fact a single person who is in disguise. Other commonalities among these syndromes are that they are discriminatory in which object(s) are misidentified. Lastly, dopamine
hyperactivity is evident in all DMS syndromes and thus, all syndromes utilize antipsychotic
medications to help control DMS.
Coexistence of Capgras
Delusional Misidentification Syndromes contain four types of syndromes: the syndrome of subjective doubles, the syndrome of intermetamorphosis
, Fregoli syndrome and Capgras syndrome. Of the four, Fregoli syndrome is the least frequent, followed by Capgras. Of more rarity is the coexistence of both Fregoli and Capgras syndromes. Coexistence of DMSs are enhanced when coupled with other mental disorders such as schizophrenia, bipolar disorder and other mood disorders. Depersonalization
and derealization
symptoms are usually manifested in patients exhibiting two misidentification delusions. However, such symptoms have been witnessed to cease once the coexisting DMSs are fully developed.
Signs and symptoms of Fregoli's:
follows. Antipsychotic drugs are the front runners in treatment for Fregoli and other DMSs. In addition to antipsychotics, anticonvulsants and antidepressants are also prescribed in some treatment courses. If a Fregoli patient has other psychological disorders, treatment often resulted in the use of trifluperazine.
, also known as L-DOPA, is the precursor to several catecholamines, specifically of dopamine
, epinephrine
and norepinephrine
. It is clinically used to treat Parkinson's disease
and dopamine-responsive dystonia
. Clinical studies have shown that the use of levodopa can lead to visual hallucinations and delusions. In most patients, delusions were more salient than hallucinations. Over prolonged use of levodopa, the delusions almost occupy all of a patient's attention. In experimental studies, when the concentration of levodopa decreases, the number of reported delusions decreases as well. It has been concluded that delusions related to antiparkinsonian medications are one of the leading causes of Fregoli syndrome.
targets were also performed and brain injured patients had many errors; this meant that they were deficient in their response regulation and inhibition.
The most profound finding in Roane, et al.'s paper is that performance tests on the retrieval
process of memory was significantly damaged in brain injured patients. They found, however, that these patients chose incorrect answer that were related semantically (i.e. chose vegetable instead of fruit). More importantly, test of visual memory showed that there was a severe inability in visual recollection. Overall, brain injured patients were severely impaired in many executive functions such as self-monitoring, mental flexibility
, and social reasoning. So how does this relate to the Fregoli syndrome — an illusion of positive doubles where there is an over-familiarity with the environment.
This over-familiarity may be caused by 4 reasons:
Thus, executive dysfunction appears to be necessary to identify one as having Fregoli's syndrome.
Fusiform gyrus
Current research has shown that lesions in the right temporal lobe
and the fusiform gyrus
may contribute to DMSs. MRIs of patients exemplifying Fregoli symptoms have shown parahippocampal and hippocampal damage in the anterior fusiform gyrus, as well as the middle and inferior of the right temporal gyri. The inferior and medial of the right temporal gyri are the storage locations for long term memory in retrieving information on visual recognition, specifically of faces; thus, damage to these intricate connections could be one of the leading factors in face misidentification disorders.
Recently, a face specific area in the fusiform gyrus has been discovered and is close to the anterior fusiform gyrus. MRI studies performed by Hudson, et al. have shown lesions in the anterior fusiform gyrus, which is close to the face specific area, may also be associated with Fregoli syndrome and other DMSs. Such damage may cause disruption in long term visual memory and lead to improper associations of human faces.
On another note, our brain interprets visual scenes in two pathways: one is via the parietal
-occipital
dorsal pathway (visual spatial material is analyzed here) and second is the temporal
-occipital ventral pathway (recognizes objects and faces). Thus, lesions in either structures or disruption of delicate connections may produce DMSs.
(WM). The P300
(P stands for positive voltage potential and the 300 for the 300 millisecond poststimulus) is an index of WM and is used during a WM test in DMS patients. In comparison to normal patients, DMS patients generally exhibit an attenuated amplitude of P300 at many abductions. These patients also exhibit prolonged latencies of P300 at all abductions. These implications suggest that DMSs are accompanied by abnormal WM, specifically affecting the prefrontal cortex
(both outside and inside).
Past studies have shown correlations between DMS and damages to the right hemispheric function, which has an array of functions (insight, 3D shapes, art awareness, imagination, left-hand control, music awareness, etc.). In recent years, the P300 auditory component, which forms in response to a detection task that occurs a short time after a stimulus, has acquired a great deal of recognition. The P300 component is an index of mental activity in that its amplitude increases highly with increased stimuli. This P300 component is correlated with updating the working memory to what is expected in the environment. Other findings enhance the belief that defects in the working memory are associated with DMS. Papageorgio et al.'s paper, psychological evidence for altered information processing in delusional misidentification syndromes, hypothesized that electrophysiological brain activity in the working memory and P300 component can help identify the mechanisms of DMS. Thus, they concentrated on P300 released during a working memory test in DMS patients.
Papageorgio et al. also found that DMS patients had a lower P300 amplitude in the right hemisphere compared to the control group (non-DMS patients). From this result, the researchers implied that shorter P300 amplitudes are highly correlated with gray matter
abnormalities; this finding is consistent with the DMS patients’ characteristics and the presence of gray matter deterioration. DMS patients were also found to have prolonged P300 lag and their memory performance was lower than the control groups. The researchers were, thus, able to imply that DMS patients have trouble in focusing their resources to a stimulus; this was hypothesized to be caused by the neurodegeneration
of the right hemisphere. Overall, other research studies have also provided evidence in the correlation of DMS and gray matter degeneration of the right frontal region, which controls attentional resources. This research is important because it can help determine the mechanisms of DMS, which can then help conjure a more effective target drug and/or treatment plan for those suffering from DMS.
Delusion
A delusion is a false belief held with absolute conviction despite superior evidence. Unlike hallucinations, delusions are always pathological...
al belief that different people are in fact a single person who changes appearance or is in disguise. The syndrome may be related to a brain lesion, and is often of a paranoid
Paranoia
Paranoia [] is a thought process believed to be heavily influenced by anxiety or fear, often to the point of irrationality and delusion. Paranoid thinking typically includes persecutory beliefs, or beliefs of conspiracy concerning a perceived threat towards oneself...
nature with the delusional person believing themselves persecuted
Persecution
Persecution is the systematic mistreatment of an individual or group by another group. The most common forms are religious persecution, ethnic persecution, and political persecution, though there is naturally some overlap between these terms. The inflicting of suffering, harassment, isolation,...
by the person they believe is in disguise.
A person with the Fregoli delusion can also inaccurately replicate places, objects, and events. This disorder can be explained by "associative nodes." The associative nodes serve as a biological link of information about other people with a particular familiar face (to the patient). This means that any face that is similar to a recognizable face to the patient, the patient will recall that face as the person they know.
The Fregoli delusion is classed both as a monothematic delusion
Monothematic delusion
A monothematic delusion is a delusional state that only concerns one particular topic. This is contrasted by what is sometimes called multi-thematic or polythematic delusions where the person has a range of delusions...
, since it only encompasses one delusional topic, and as a delusional misidentification syndrome
Delusional misidentification syndrome
Delusional misidentification syndrome is an umbrella term, introduced by Christodoulou for a group of delusional disorders that occur in the context of mental or neurological illness. They all involve a belief that the identity of a person, object or place has somehow changed or has been altered...
, a class of delusional beliefs that involves misidentifying people, places, or objects. Like Capgras delusion
Capgras delusion
The Capgras delusion theory is a disorder in which a person holds a delusion that a friend, spouse, parent, or other close family member has been replaced by an identical-looking impostor...
, psychiatrists believe it is related to a breakdown in normal face perception
Face perception
Face perception is the process by which the brain and mind understand and interpret the face, particularly the human face.The human face's proportions and expressions are important to identify origin, emotional tendencies, health qualities, and some social information. From birth, faces are...
.
History of Fregoli syndrome
The condition is named after the Italian actor Leopoldo FregoliLeopoldo Fregoli
Leopoldo Fregoli was a stage star and early Italian actor.-Quick-change Artist:Fregoli was the greatest protean artist of his day...
who was renowned for his ability to make quick changes of appearance during his stage act.
P. Courbon and G. Fail first reported the condition in a 1927 paper (Syndrome d’illusion de Frégoli et schizophrénie). They described a 27-year-old woman who believed she was being persecuted by two actors she often saw at the theatre. She believed these people pursued her closely, taking the form of people she knew or met.
Delusional misidentification syndromes and Fregoli
Delusional misidentification syndromesDelusional misidentification syndrome
Delusional misidentification syndrome is an umbrella term, introduced by Christodoulou for a group of delusional disorders that occur in the context of mental or neurological illness. They all involve a belief that the identity of a person, object or place has somehow changed or has been altered...
(DMS) are rooted in the inability to register the identity of something, whether it is an object, event, place or even a person. There are various forms of DMS, such as the syndrome of subjective doubles, intermetamorphosis
Intermetamorphosis
Intermetamorphosis is a delusional misidentification syndrome, related to agnosia. The main symptoms consist patients believing that they can see others change into some one else both external appearance and internal personality...
, Capgras syndrome and Fregoli syndrome. However, all of these various syndromes have a common denominator: they are all due to malfunctional familiarity processing during information processing. The most common syndromes are Capgras and Fregoli. Capgras syndrome is the delusional belief that a friend, family member, etc. has been replaced by a twin impostor. Fregoli syndrome is the delusional belief that different people are in fact a single person who is in disguise. Other commonalities among these syndromes are that they are discriminatory in which object(s) are misidentified. Lastly, dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
hyperactivity is evident in all DMS syndromes and thus, all syndromes utilize antipsychotic
Antipsychotic
An antipsychotic is a tranquilizing psychiatric medication primarily used to manage psychosis , particularly in schizophrenia and bipolar disorder. A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s...
medications to help control DMS.
Coexistence of CapgrasCapgras delusionThe Capgras delusion theory is a disorder in which a person holds a delusion that a friend, spouse, parent, or other close family member has been replaced by an identical-looking impostor...
and Fregoli
Delusional Misidentification Syndromes contain four types of syndromes: the syndrome of subjective doubles, the syndrome of intermetamorphosisIntermetamorphosis
Intermetamorphosis is a delusional misidentification syndrome, related to agnosia. The main symptoms consist patients believing that they can see others change into some one else both external appearance and internal personality...
, Fregoli syndrome and Capgras syndrome. Of the four, Fregoli syndrome is the least frequent, followed by Capgras. Of more rarity is the coexistence of both Fregoli and Capgras syndromes. Coexistence of DMSs are enhanced when coupled with other mental disorders such as schizophrenia, bipolar disorder and other mood disorders. Depersonalization
Depersonalization
Depersonalization is an anomaly of the mechanism by which an individual has self-awareness. It is a feeling of watching oneself act, while having no control over a situation. Sufferers feel they have changed, and the world has become less real, vague, dreamlike, or lacking in significance...
and derealization
Derealization
Derealization is an alteration in the perception or experience of the external world so that it seems unreal. Other symptoms include feeling as though one's environment is lacking in spontaneity, emotional coloring and depth. It is a dissociative symptom of many conditions, such as psychiatric and...
symptoms are usually manifested in patients exhibiting two misidentification delusions. However, such symptoms have been witnessed to cease once the coexisting DMSs are fully developed.
Signs and symptoms
Fregoli syndrome is the belief that people you know have been disguised to appear as strangers.Signs and symptoms of Fregoli's:
- delusions
- visual memory deficit
- deficit in self-monitoring
- deficit in self-awarenessSelf-awarenessSelf-awareness is the capacity for introspection and the ability to reconcile oneself as an individual separate from the environment and other individuals...
- hallucinations
- deficit in executive functionsExecutive functionsThe executive system is a theorized cognitive system in psychology that controls and manages other cognitive processes. It is responsible for processes that are sometimes referred to as the executive function, executive functions, supervisory attentional system, or cognitive control...
- deficit in cognitive flexibilityCognitive flexibilityCognitive flexibility is the term used to describe one of the executive functions; a function which is an important component of human behavior; the ability to switch behavioral response according to the context of the situation...
- history of seizure activity
- epileptogenic activity
Drug treatment options
Once it has been positively identified, effective pharmacotherapyPharmacotherapy
Pharmacotherapy is the treatment of disease through the administration of drugs. As such, it is considered part of the larger category of therapy....
follows. Antipsychotic drugs are the front runners in treatment for Fregoli and other DMSs. In addition to antipsychotics, anticonvulsants and antidepressants are also prescribed in some treatment courses. If a Fregoli patient has other psychological disorders, treatment often resulted in the use of trifluperazine.
Levodopa treatment
LevodopaLevodopa
L-DOPA is a chemical that is made and used as part of the normal biology of some animals and plants. Some animals including humans make it via biosynthesis from the amino acid L-tyrosine. L-DOPA is the precursor to the neurotransmitters dopamine, norepinephrine , and epinephrine collectively...
, also known as L-DOPA, is the precursor to several catecholamines, specifically of dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
, epinephrine
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
and norepinephrine
Norepinephrine
Norepinephrine is the US name for noradrenaline , a catecholamine with multiple roles including as a hormone and a neurotransmitter...
. It is clinically used to treat Parkinson's disease
Parkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...
and dopamine-responsive dystonia
Dystonia
Dystonia is a neurological movement disorder, in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning or reaction to...
. Clinical studies have shown that the use of levodopa can lead to visual hallucinations and delusions. In most patients, delusions were more salient than hallucinations. Over prolonged use of levodopa, the delusions almost occupy all of a patient's attention. In experimental studies, when the concentration of levodopa decreases, the number of reported delusions decreases as well. It has been concluded that delusions related to antiparkinsonian medications are one of the leading causes of Fregoli syndrome.
Traumatic brain injury
Injury to the right frontal and left temporo-parietal areas can cause Fregoli syndrome. Research by Roane, et al. have shown that significant deficits in executive and memory functions follows shortly after damage in the right frontal or left temporoparietal areas. Tests performed on patients that have suffered from a brain injury revealed that basic attention ability and visuomotor processing speed are typically normal. However, these patients made many errors when they were called to participate in detailed attention tasks. Selective attention tests involving auditorySound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
targets were also performed and brain injured patients had many errors; this meant that they were deficient in their response regulation and inhibition.
The most profound finding in Roane, et al.'s paper is that performance tests on the retrieval
Retrieval
Retrieval could refer to:* Information retrieval* Text retrieval* Image retrieval* Document retrieval* Music information retrieval* Medical retrieval* Data retrieval* Knowledge retrieval...
process of memory was significantly damaged in brain injured patients. They found, however, that these patients chose incorrect answer that were related semantically (i.e. chose vegetable instead of fruit). More importantly, test of visual memory showed that there was a severe inability in visual recollection. Overall, brain injured patients were severely impaired in many executive functions such as self-monitoring, mental flexibility
Cognitive flexibility
Cognitive flexibility is the term used to describe one of the executive functions; a function which is an important component of human behavior; the ability to switch behavioral response according to the context of the situation...
, and social reasoning. So how does this relate to the Fregoli syndrome — an illusion of positive doubles where there is an over-familiarity with the environment.
This over-familiarity may be caused by 4 reasons:
- impaired self monitoring — passive acceptance of inaccurate conclusions
- faulty filtering — tendency to select salient associations rather than a relevant one
- mnemonicMnemonicA mnemonic , or mnemonic device, is any learning technique that aids memory. To improve long term memory, mnemonic systems are used to make memorization easier. Commonly encountered mnemonics are often verbal, such as a very short poem or a special word used to help a person remember something,...
association from routine thoughts - perseverationPerseverationPerseveration is the repetition of a particular response, such as a word, phrase, or gesture, despite the absence or cessation of a stimulus, usually caused by brain injury or other organic disorder. If an issue has been fully explored and discussed to a point of resolution, it is not uncommon for...
— unable to come up with an alternate hypothesis
Thus, executive dysfunction appears to be necessary to identify one as having Fregoli's syndrome.
Fusiform gyrusFusiform gyrusThe fusiform gyrus is part of the temporal lobe in Brodmann Area 37. It is also known as the occipitotemporal gyrus. Other sources have the fusiform gyrus above the occipitotemporal gyrus and underneath the parahippocampal gyrus....
Current research has shown that lesions in the right temporal lobeTemporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
and the fusiform gyrus
Fusiform gyrus
The fusiform gyrus is part of the temporal lobe in Brodmann Area 37. It is also known as the occipitotemporal gyrus. Other sources have the fusiform gyrus above the occipitotemporal gyrus and underneath the parahippocampal gyrus....
may contribute to DMSs. MRIs of patients exemplifying Fregoli symptoms have shown parahippocampal and hippocampal damage in the anterior fusiform gyrus, as well as the middle and inferior of the right temporal gyri. The inferior and medial of the right temporal gyri are the storage locations for long term memory in retrieving information on visual recognition, specifically of faces; thus, damage to these intricate connections could be one of the leading factors in face misidentification disorders.
Recently, a face specific area in the fusiform gyrus has been discovered and is close to the anterior fusiform gyrus. MRI studies performed by Hudson, et al. have shown lesions in the anterior fusiform gyrus, which is close to the face specific area, may also be associated with Fregoli syndrome and other DMSs. Such damage may cause disruption in long term visual memory and lead to improper associations of human faces.
On another note, our brain interprets visual scenes in two pathways: one is via the parietal
Parietal
Parietal may refer to:*Parietal placentation*Parietal lobe of the brain*Parietal bone of the skull*Parietal scales of a snake lie in the general region of the parietal bone*Parietal cell in the stomach*Parietal pleura...
-occipital
Occipital
The word occipital, in zoology, pertains to the occiput .Occipital is a descriptor for several areas of animal & human anatomy.*External occipital protuberance* Internal occipital crest* Greater occipital nerve...
dorsal pathway (visual spatial material is analyzed here) and second is the temporal
Temporal
Temporal can refer to:* of or relating to time** Temporality in philosophy** Temporal database, a database recording aspects of time varying values** The Temporal power of the Popes of the Roman Catholic Church...
-occipital ventral pathway (recognizes objects and faces). Thus, lesions in either structures or disruption of delicate connections may produce DMSs.
Abnormal P300
Delusional misidentification syndrome is thought to occur due to a dissociation between identification and recognition processes. The integration of information for further processing is referred to as working memoryWorking memory
Working memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
(WM). The P300
P300
The P300 wave is an event related potential elicited by infrequent, task-relevant stimuli. It is considered to be an endogenous potential as its occurrence links not to the physical attributes of a stimulus but to a person's reaction to the stimulus. More specifically, the P300 is thought to...
(P stands for positive voltage potential and the 300 for the 300 millisecond poststimulus) is an index of WM and is used during a WM test in DMS patients. In comparison to normal patients, DMS patients generally exhibit an attenuated amplitude of P300 at many abductions. These patients also exhibit prolonged latencies of P300 at all abductions. These implications suggest that DMSs are accompanied by abnormal WM, specifically affecting the prefrontal cortex
Prefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...
(both outside and inside).
Past studies have shown correlations between DMS and damages to the right hemispheric function, which has an array of functions (insight, 3D shapes, art awareness, imagination, left-hand control, music awareness, etc.). In recent years, the P300 auditory component, which forms in response to a detection task that occurs a short time after a stimulus, has acquired a great deal of recognition. The P300 component is an index of mental activity in that its amplitude increases highly with increased stimuli. This P300 component is correlated with updating the working memory to what is expected in the environment. Other findings enhance the belief that defects in the working memory are associated with DMS. Papageorgio et al.'s paper, psychological evidence for altered information processing in delusional misidentification syndromes, hypothesized that electrophysiological brain activity in the working memory and P300 component can help identify the mechanisms of DMS. Thus, they concentrated on P300 released during a working memory test in DMS patients.
Papageorgio et al. also found that DMS patients had a lower P300 amplitude in the right hemisphere compared to the control group (non-DMS patients). From this result, the researchers implied that shorter P300 amplitudes are highly correlated with gray matter
Gray Matter
"Gray Matter" is a short story by Stephen King, first published in the October 1973 issue of Cavalier magazine, and later collected in King's 1978 collection Night Shift. It is set in the same area as King's novel Dreamcatcher.-Setting:...
abnormalities; this finding is consistent with the DMS patients’ characteristics and the presence of gray matter deterioration. DMS patients were also found to have prolonged P300 lag and their memory performance was lower than the control groups. The researchers were, thus, able to imply that DMS patients have trouble in focusing their resources to a stimulus; this was hypothesized to be caused by the neurodegeneration
Neurodegeneration
Neurodegeneration is the umbrella term for the progressive loss of structure or function of neurons, including death of neurons. Many neurodegenerative diseases including Parkinson’s, Alzheimer’s, and Huntington’s occur as a result of neurodegenerative processes. As research progresses, many...
of the right hemisphere. Overall, other research studies have also provided evidence in the correlation of DMS and gray matter degeneration of the right frontal region, which controls attentional resources. This research is important because it can help determine the mechanisms of DMS, which can then help conjure a more effective target drug and/or treatment plan for those suffering from DMS.
Current research
The study of DMS currently remains controversial, as they are often coupled with many psychological disorders (i.e. schizophrenia, bipolar disorder, obsessive compulsive disorder, etc.). Although there is a plethora of information on DMS, there are still many mysteries of the physiological and anatomical details of DMS. An accurate semiological analysis of higher visual anomalies and their corresponding topographic sites may help elucidate the aetiology of Fregoli's and other misidentification disorders.See also
- Capgras delusionCapgras delusionThe Capgras delusion theory is a disorder in which a person holds a delusion that a friend, spouse, parent, or other close family member has been replaced by an identical-looking impostor...
- DelusionDelusionA delusion is a false belief held with absolute conviction despite superior evidence. Unlike hallucinations, delusions are always pathological...
- Delusional misidentification syndromeDelusional misidentification syndromeDelusional misidentification syndrome is an umbrella term, introduced by Christodoulou for a group of delusional disorders that occur in the context of mental or neurological illness. They all involve a belief that the identity of a person, object or place has somehow changed or has been altered...
- Monothematic delusionMonothematic delusionA monothematic delusion is a delusional state that only concerns one particular topic. This is contrasted by what is sometimes called multi-thematic or polythematic delusions where the person has a range of delusions...
- SchizophreniaSchizophreniaSchizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
- Cotard's Syndrome
- ErotomaniaErotomaniaErotomania is a type of delusion in which the affected person believes that another person, usually a stranger or famous person, is in love with him or her. The illness often occurs during psychosis, especially in patients with schizophrenia or bipolar mania...
- PsychosisPsychosisPsychosis means abnormal condition of the mind, and is a generic psychiatric term for a mental state often described as involving a "loss of contact with reality"...
- Paramnesia
- ProsopagnosiaProsopagnosiaProsopagnosia is a disorder of face perception where the ability to recognize faces is impaired, while the ability to recognize other objects may be relatively intact...
- AgnosiaAgnosiaAgnosia is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss...