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Historical Perspective:
== Historical Perspective: ==
It is a psychiatric syndrome that is historically known as a shared psychotic disorder due to its transmitted properties that involve the sharing of symptoms from one individual to another. The concept of the disease was first put forward in the 19th century by Lasègue and Falret in France and they coined the term Folie à deux for this rare transmitted disease however some other terms are also used synonymously such as double insanity and psychosis of association.<ref name="pmidPMID: 16895601">{{cite journal| author=Arnone D, Patel A, Tan GM| title=The nosological significance of Folie à Deux: a review of the literature. | journal=Ann Gen Psychiatry | year= 2006 | volume= 5 | issue=  | pages= 11 | pmid=PMID: 16895601 | doi=10.1186/1744-859X-5-11 | pmc=1559622 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16895601  }} </ref>


It is a psychiatric syndrome that is historically known as a shared psychotic disorder due to its
== Pathophysiology: ==
transmitted properties that involve the sharing of symptoms from one individual to another. The
Shared psychiatric disorder(SPD) also known as folie à deux, is a rare chronic psychiatric problem in which the symptoms are transferred from one psychotic individual to another or among multiple healthy individuals who have close associations such as family members, or close friends with this disease can extend from the original subject to three or more. based on the number of individuals involved this the disorder can be named as, folie trios when three individuals are engaged in case of four  folie a
concept of the disease was first put forward in the 19th century by Lasègue and Falret in France and they
quatre, five  folie a cinq, or when sometimes a whole family is involved then it is termed as folie a Famille   <ref name="pmidPMID: 33098221">{{cite journal| author=Torales J, García O, Barrios I, O'Higgins M, Castaldelli-Maia JM, Ventriglio A | display-authors=etal| title=Delusional infestation: Clinical presentations, diagnosis, and management. | journal=J Cosmet Dermatol | year= 2020 | volume= 19 | issue= 12 | pages= 3183-3188 | pmid=PMID: 33098221 | doi=10.1111/jocd.13786 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=33098221 }} </ref> The pathophysiology of the diseases is not known but an investigation suggest that the occurrence of the diseases may occur due to certain brain differences ( posterior fossa lesion) but still, the association between brain abnormality and the diseases is not clear  the
coined the term Folie à deux for this rare transmitted disease however some other terms are also used
the disorder can be of any type most commonly observed are persecutory and grandeur delusions but the races are vary.
synonymously such as double insanity and psychosis of association.<ref name="pmidPMID: 16895601">{{cite journal| author=Arnone D, Patel A, Tan GM| title=The nosological significance of Folie à Deux: a review of the literature. | journal=Ann Gen Psychiatry | year= 2006 | volume= 5 | issue= | pages= 11 | pmid=PMID: 16895601 | doi=10.1186/1744-859X-5-11 | pmc=1559622 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16895601 }} </ref>


Pathophysiology:
== Causes: ==
Shared psychiatric disorder(SPD) also known as folie à deux, is a rare chronic psychiatric problem in
The cause of the diseases is still not known, however, some risk factors are observed that can cause the diseases including genetic and environmental factors are the determinants of the disease such as social isolation and close association with the individual belief in unusual things.
which the symptoms are transferred from one psychotic individual to another or among multiple
healthy individuals who have close associations such as family members, or close friends with this disease
can extend from the original subject to three or more. based on the number of individuals involved this
the disorder can be named as, folie trios when three individuals are engaged in case of four  folie a
quatre, five  folie a cinq, or when sometimes a whole family is involved then it is termed as folie a
Famille   <ref name="pmidPMID: 33098221">{{cite journal| author=Torales J, García O, Barrios I, O'Higgins M, Castaldelli-Maia JM, Ventriglio A | display-authors=etal| title=Delusional infestation: Clinical presentations, diagnosis, and management. | journal=J Cosmet Dermatol | year= 2020 | volume= 19 | issue= 12 | pages= 3183-3188 | pmid=PMID: 33098221 | doi=10.1111/jocd.13786 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=33098221  }} </ref> The pathophysiology of the diseases is not known but an investigation
suggest that the occurrence of the diseases may occur due to certain brain differences ( posterior fossa
lesion) but still, the association between brain abnormality and the diseases is not clear  the
the disorder can be of any type most commonly observed are persecutory and grandeur delusions but the
races are vary.


Causes:
=== Genetic factors: ===
The cause of the diseases is still not known, however, some risk factors are observed that can cause the
diseases including genetic and environmental factors are the determinants of the disease such as social
isolation and close association with the individual belief in unusual things.
 
Genetic factors:
SPD can be influenced by genetic predisposition to psychosis, such as blood relations with the primary
SPD can be influenced by genetic predisposition to psychosis, such as blood relations with the primary
patient investigation has suggested that the individual with the disease is initially diagnosed with
patient investigation has suggested that the individual with the disease is initially diagnosed with [[schizophrenia]] which is a psychotic disorder that is caused by genetic factors. Studies suggest that the patients diagnosed with shared psychotic disorder are reported as monozygotic twins. <ref name="pmidPMID: 30328525(3)">{{cite journal| author=Vigo L, Ilzarbe D, Baeza I, Banerjea P, Kyriakopoulos M| title=Shared psychotic disorder in children and young people: a systematic review. | journal=Eur Child Adolesc Psychiatry | year= 2019 | volume= 28 | issue= 12 | pages= 1555-1566 | pmid=PMID: 30328525(3) | doi=10.1007/s00787-018-1236-7 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30328525  }} </ref>
schizophrenia which is a psychotic disorder that is caused by genetic factors. Studies suggest
that the patients diagnosed with shared psychotic disorder are reported as monozygotic twins.
<ref name="pmidPMID: 30328525(3)">{{cite journal| author=Vigo L, Ilzarbe D, Baeza I, Banerjea P, Kyriakopoulos M| title=Shared psychotic disorder in children and young people: a systematic review. | journal=Eur Child Adolesc Psychiatry | year= 2019 | volume= 28 | issue= 12 | pages= 1555-1566 | pmid=PMID: 30328525(3) | doi=10.1007/s00787-018-1236-7 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30328525  }} </ref>


Isolation:
=== Isolation: ===
Isolation from the social environment can act as a risk factor for the development of diseases it can
Isolation from the social environment can act as a risk factor for the development of diseases it can cause individuals to believe in unusual things and it can be spread to others who are in a relationship because they rely on each other’s information, making it easier to spread false belief.
cause individuals to believe in unusual things and it can be spread to others who are in a relationship
because they rely on each other’s information, making it easier to spread false belief.


Close Association:
=== Close Association: ===
Stressful life events can lead to delusional beliefs. In a relationship, if one partner holds unusual
Stressful life events can lead to delusional beliefs. In a relationship, if one partner holds unusual beliefs, it can create stress, leading the other to adopt those false ideas to avoid conflict.<ref name="pmidPMID: 22810994">{{cite journal| author=Lew-Starowicz M| title=Shared psychotic disorder with sexual delusions. | journal=Arch Sex Behav | year= 2012 | volume= 41 | issue= 6 | pages= 1515-20 | pmid=PMID: 22810994 | doi=10.1007/s10508-012-9992-9 | pmc=3501166 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22810994  }} </ref>
beliefs, it can create stress, leading the other to adopt those false ideas to avoid conflict.
<ref name="pmidPMID: 22810994">{{cite journal| author=Lew-Starowicz M| title=Shared psychotic disorder with sexual delusions. | journal=Arch Sex Behav | year= 2012 | volume= 41 | issue= 6 | pages= 1515-20 | pmid=PMID: 22810994 | doi=10.1007/s10508-012-9992-9 | pmc=3501166 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22810994  }} </ref>


Epidemiology and Demographics:
== Epidemiology and Demographics: ==
The incidence of the cases reported in the mental hospital is around 1.7-2.6 % and the true rate
The incidence of the cases reported in the mental hospital is around 1.7-2.6 % and the true rate
of prevalence is still unknown due to undocumented and under diagnostic cases<ref name="pmidPMID: 30328525">{{cite journal| author=Vigo L, Ilzarbe D, Baeza I, Banerjea P, Kyriakopoulos M| title=Shared psychotic disorder in children and young people: a systematic review. | journal=Eur Child Adolesc Psychiatry | year= 2019 | volume= 28 | issue= 12 | pages= 1555-1566 | pmid=PMID: 30328525 | doi=10.1007/s00787-018-1236-7 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30328525  }} </ref>
of prevalence is still unknown due to undocumented and under diagnostic cases<ref name="pmidPMID: 30328525">{{cite journal| author=Vigo L, Ilzarbe D, Baeza I, Banerjea P, Kyriakopoulos M| title=Shared psychotic disorder in children and young people: a systematic review. | journal=Eur Child Adolesc Psychiatry | year= 2019 | volume= 28 | issue= 12 | pages= 1555-1566 | pmid=PMID: 30328525 | doi=10.1007/s00787-018-1236-7 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30328525  }} </ref>


Age:
=== Age: ===
This disease is observed in various age groups with cases reported in children, adults, and the elderly
This disease is observed in various age groups with cases reported in children, adults, and the elderly.
Gender:
 
=== Gender: ===
This shared psychotic disorder is common in Female <ref name="pmidPMID: 17521515">{{cite journal| author=Shimizu M, Kubota Y, Toichi M, Baba H| title=Folie à deux and shared psychotic disorder. | journal=Curr Psychiatry Rep | year= 2007 | volume= 9 | issue= 3 | pages= 200-5 | pmid=PMID: 17521515 | doi=10.1007/s11920-007-0019-5 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17521515  }} </ref>
This shared psychotic disorder is common in Female <ref name="pmidPMID: 17521515">{{cite journal| author=Shimizu M, Kubota Y, Toichi M, Baba H| title=Folie à deux and shared psychotic disorder. | journal=Curr Psychiatry Rep | year= 2007 | volume= 9 | issue= 3 | pages= 200-5 | pmid=PMID: 17521515 | doi=10.1007/s11920-007-0019-5 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17521515  }} </ref>
Symptoms:
The syndrome is diagnosed when two or more individuals who live in proximity are isolated from
the social environment and have very little interaction with other people. These people have
psychotic symptoms, major depression and anxiety, auditory and visual hallucinations, and delusional
beliefs.<ref name="pmidPMID: 27906088">{{cite journal| author=Vargas Alves Nunes A, Odebrecht Vargas Nunes S, Strano T, Pascolat G, Schier Doria GM, Nasser Ehlke M| title=Folie à Deux and its interaction with early life stress: a case report. | journal=J Med Case Rep | year= 2016 | volume= 10 | issue= 1 | pages= 339 | pmid=PMID: 27906088 | doi=10.1186/s13256-016-1128-8 | pmc=5134243 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27906088  }} </ref>


Diagnosis:
== Symptoms: ==
Laboratory Findings:
The syndrome is diagnosed when two or more individuals who live in proximity are isolated from the social environment and have very little interaction with other people. These people have psychotic symptoms, major depression and [[anxiety]], auditory and visual [[Hallucination|hallucinations]], and delusional beliefs.<ref name="pmidPMID: 27906088">{{cite journal| author=Vargas Alves Nunes A, Odebrecht Vargas Nunes S, Strano T, Pascolat G, Schier Doria GM, Nasser Ehlke M| title=Folie à Deux and its interaction with early life stress: a case report. | journal=J Med Case Rep | year= 2016 | volume= 10 | issue= 1 | pages= 339 | pmid=PMID: 27906088 | doi=10.1186/s13256-016-1128-8 | pmc=5134243 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27906088  }} </ref>
 
== Diagnosis: ==
 
=== Laboratory Findings: ===
Like other diseases, there is no Laboratory test or scan available to rule out the SPD.
Like other diseases, there is no Laboratory test or scan available to rule out the SPD.
Physical Examination:
 
=== Physical Examination: ===
Physical examination will be done by the respected physician to check out the problem that is
Physical examination will be done by the respected physician to check out the problem that is
causing symptoms like brain injuries, infection, and drug use.
causing symptoms like brain injuries, infection, and drug use.
Psychiatric evaluation:
 
=== Psychiatric evaluation: ===
Later physical evaluation both partners will be asses by the mental health professional to understand
Later physical evaluation both partners will be asses by the mental health professional to understand
their thoughts feelings and emotions and this part of the diagnosis is challenging because sometimes
their thoughts feelings and emotions and this part of the diagnosis is challenging because sometimes
primary partner will try to hide the problem and protect the delusion.
primary partner will try to hide the problem and protect the delusion.
Past History:
 
=== Past History: ===
It is important to find out the history of the individual from the third person to get the complete
It is important to find out the history of the individual from the third person to get the complete
picture of the situation<ref name="pmidPMID: 17521515">{{cite journal| author=Shimizu M, Kubota Y, Toichi M, Baba H| title=Folie à deux and shared psychotic disorder. | journal=Curr Psychiatry Rep | year= 2007 | volume= 9 | issue= 3 | pages= 200-5 | pmid=PMID: 17521515 | doi=10.1007/s11920-007-0019-5 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17521515  }} </ref>
picture of the situation<ref name="pmidPMID: 17521515">{{cite journal| author=Shimizu M, Kubota Y, Toichi M, Baba H| title=Folie à deux and shared psychotic disorder. | journal=Curr Psychiatry Rep | year= 2007 | volume= 9 | issue= 3 | pages= 200-5 | pmid=PMID: 17521515 | doi=10.1007/s11920-007-0019-5 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17521515  }} </ref>


Treatment:
== Treatment: ==
The treatment plan varies from person to person each case is unique so the treatment plan should be
The treatment plan varies from person to person each case is unique so the treatment plan should be tailored. The available treatment options for the patient are separation and pharmacotherapy with [[antipsychotics]]
tailored. The available treatment options for the patient are separation and pharmacotherapy with
 
antipsychotics
=== Separation: ===
Separation:
Separating the partners can improve the symptoms sometimes but it makes the situation worsen.
Separating the partners can improve the symptoms sometimes but it makes the situation worsen.
Pharmacotherapy with antipsychotics:
 
=== Pharmacotherapy with antipsychotics: ===
It can play a significant role in the treatment of diseases these are used to manage the symptoms
It can play a significant role in the treatment of diseases these are used to manage the symptoms
associated with the diseases it stabilizes the individual by reducing the intensity of the delusion the
associated with the diseases it stabilizes the individual by reducing the intensity of the delusion the
Antipsychotics are effective in the acute phase of the diseases it include quetiapine, aripiprazole,
Antipsychotics are effective in the acute phase of the diseases it include quetiapine, aripiprazole,
benzodiazepines, and a second generation antipsychotic<ref name="pmidPMID: 35548660">{{cite journal| author=Schopfer Q, Eshmawey M| title=Shared Psychotic Disorder in Old Age: Syndrome of Folie à Deux. | journal=Case Rep Psychiatry | year= 2022 | volume= 2022 | issue=  | pages= 8811140 | pmid=PMID: 35548660 | doi=10.1155/2022/8811140 | pmc=9085334 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=35548660  }} </ref>
benzodiazepines, and a second generation antipsychotic<ref name="pmidPMID: 35548660">{{cite journal| author=Schopfer Q, Eshmawey M| title=Shared Psychotic Disorder in Old Age: Syndrome of Folie à Deux. | journal=Case Rep Psychiatry | year= 2022 | volume= 2022 | issue=  | pages= 8811140 | pmid=PMID: 35548660 | doi=10.1155/2022/8811140 | pmc=9085334 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=35548660  }} </ref>
== Reference ==

Latest revision as of 07:03, 7 September 2024

Historical Perspective:

It is a psychiatric syndrome that is historically known as a shared psychotic disorder due to its transmitted properties that involve the sharing of symptoms from one individual to another. The concept of the disease was first put forward in the 19th century by Lasègue and Falret in France and they coined the term Folie à deux for this rare transmitted disease however some other terms are also used synonymously such as double insanity and psychosis of association.[1]

Pathophysiology:

Shared psychiatric disorder(SPD) also known as folie à deux, is a rare chronic psychiatric problem in which the symptoms are transferred from one psychotic individual to another or among multiple healthy individuals who have close associations such as family members, or close friends with this disease can extend from the original subject to three or more. based on the number of individuals involved this the disorder can be named as, folie trios when three individuals are engaged in case of four  folie a quatre, five  folie a cinq, or when sometimes a whole family is involved then it is termed as folie a Famille   [2] The pathophysiology of the diseases is not known but an investigation suggest that the occurrence of the diseases may occur due to certain brain differences ( posterior fossa lesion) but still, the association between brain abnormality and the diseases is not clear the the disorder can be of any type most commonly observed are persecutory and grandeur delusions but the races are vary.

Causes:

The cause of the diseases is still not known, however, some risk factors are observed that can cause the diseases including genetic and environmental factors are the determinants of the disease such as social isolation and close association with the individual belief in unusual things.

Genetic factors:

SPD can be influenced by genetic predisposition to psychosis, such as blood relations with the primary patient investigation has suggested that the individual with the disease is initially diagnosed with schizophrenia which is a psychotic disorder that is caused by genetic factors. Studies suggest that the patients diagnosed with shared psychotic disorder are reported as monozygotic twins. [3]

Isolation:

Isolation from the social environment can act as a risk factor for the development of diseases it can cause individuals to believe in unusual things and it can be spread to others who are in a relationship because they rely on each other’s information, making it easier to spread false belief.

Close Association:

Stressful life events can lead to delusional beliefs. In a relationship, if one partner holds unusual beliefs, it can create stress, leading the other to adopt those false ideas to avoid conflict.[4]

Epidemiology and Demographics:

The incidence of the cases reported in the mental hospital is around 1.7-2.6 % and the true rate of prevalence is still unknown due to undocumented and under diagnostic cases[5]

Age:

This disease is observed in various age groups with cases reported in children, adults, and the elderly.

Gender:

This shared psychotic disorder is common in Female [6]

Symptoms:

The syndrome is diagnosed when two or more individuals who live in proximity are isolated from the social environment and have very little interaction with other people. These people have psychotic symptoms, major depression and anxiety, auditory and visual hallucinations, and delusional beliefs.[7]

Diagnosis:

Laboratory Findings:

Like other diseases, there is no Laboratory test or scan available to rule out the SPD.

Physical Examination:

Physical examination will be done by the respected physician to check out the problem that is causing symptoms like brain injuries, infection, and drug use.

Psychiatric evaluation:

Later physical evaluation both partners will be asses by the mental health professional to understand their thoughts feelings and emotions and this part of the diagnosis is challenging because sometimes primary partner will try to hide the problem and protect the delusion.

Past History:

It is important to find out the history of the individual from the third person to get the complete picture of the situation[6]

Treatment:

The treatment plan varies from person to person each case is unique so the treatment plan should be tailored. The available treatment options for the patient are separation and pharmacotherapy with antipsychotics

Separation:

Separating the partners can improve the symptoms sometimes but it makes the situation worsen.

Pharmacotherapy with antipsychotics:

It can play a significant role in the treatment of diseases these are used to manage the symptoms associated with the diseases it stabilizes the individual by reducing the intensity of the delusion the Antipsychotics are effective in the acute phase of the diseases it include quetiapine, aripiprazole, benzodiazepines, and a second generation antipsychotic[8]

Reference

  1. Arnone D, Patel A, Tan GM (2006). "The nosological significance of Folie à Deux: a review of the literature". Ann Gen Psychiatry. 5: 11. doi:10.1186/1744-859X-5-11. PMC 1559622. PMID 16895601 PMID: 16895601 Check |pmid= value (help).
  2. Torales J, García O, Barrios I, O'Higgins M, Castaldelli-Maia JM, Ventriglio A; et al. (2020). "Delusional infestation: Clinical presentations, diagnosis, and management". J Cosmet Dermatol. 19 (12): 3183–3188. doi:10.1111/jocd.13786. PMID 33098221 PMID: 33098221 Check |pmid= value (help).
  3. Vigo L, Ilzarbe D, Baeza I, Banerjea P, Kyriakopoulos M (2019). "Shared psychotic disorder in children and young people: a systematic review". Eur Child Adolesc Psychiatry. 28 (12): 1555–1566. doi:10.1007/s00787-018-1236-7. PMID 30328525(3) PMID: 30328525(3) Check |pmid= value (help).
  4. Lew-Starowicz M (2012). "Shared psychotic disorder with sexual delusions". Arch Sex Behav. 41 (6): 1515–20. doi:10.1007/s10508-012-9992-9. PMC 3501166. PMID 22810994 PMID: 22810994 Check |pmid= value (help).
  5. Vigo L, Ilzarbe D, Baeza I, Banerjea P, Kyriakopoulos M (2019). "Shared psychotic disorder in children and young people: a systematic review". Eur Child Adolesc Psychiatry. 28 (12): 1555–1566. doi:10.1007/s00787-018-1236-7. PMID 30328525 PMID: 30328525 Check |pmid= value (help).
  6. 6.0 6.1 Shimizu M, Kubota Y, Toichi M, Baba H (2007). "Folie à deux and shared psychotic disorder". Curr Psychiatry Rep. 9 (3): 200–5. doi:10.1007/s11920-007-0019-5. PMID 17521515 PMID: 17521515 Check |pmid= value (help).
  7. Vargas Alves Nunes A, Odebrecht Vargas Nunes S, Strano T, Pascolat G, Schier Doria GM, Nasser Ehlke M (2016). "Folie à Deux and its interaction with early life stress: a case report". J Med Case Rep. 10 (1): 339. doi:10.1186/s13256-016-1128-8. PMC 5134243. PMID 27906088 PMID: 27906088 Check |pmid= value (help).
  8. Schopfer Q, Eshmawey M (2022). "Shared Psychotic Disorder in Old Age: Syndrome of Folie à Deux". Case Rep Psychiatry. 2022: 8811140. doi:10.1155/2022/8811140. PMC 9085334 Check |pmc= value (help). PMID 35548660 PMID: 35548660 Check |pmid= value (help).