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Chapter: Essentials of Psychiatry: Schizophrenia and Other Psychoses

Differential Diagnosis - Psychoses Disorder

This is similar to schizophrenia. Psychotic disorder caused by a general medical condition and substance-induced psychotic dis-order must be ruled out.

Differential Diagnosis


This is similar to schizophrenia. Psychotic disorder caused by a general medical condition and substance-induced psychotic dis-order must be ruled out. General medical conditions to be con-sidered are HIV infection, temporal lobe epilepsy, CNS tumors and cerebrovascular disease, all of which can also be associated with relatively short-lived psychotic episodes. The increas-ing number of reports of psychosis associated with the use of anabolic steroids by young men who are attempting to build up their muscles to perform better in athletic activities require care-ful history. Factitious disorder with predominantly psychological signs and symptoms and malingering may need to be ruled out in some instances.


Course and Prognosis


This is, as anticipated, variable. The DSM IV specifiers “with good prognostic features” and “without good prognostic fea-tures” though helpful in guiding the clinician, require further validation. However, confusion or perplexity at the height of the psychotic episode is the feature best correlated with good out-come. Also, the shorter the period of illness, the better the prog-nosis is likely to be. There is a significant risk of suicide in these patients. Postpsychotic depression is quite likely and should be addressed in psychotherapy. Psychotherapy may help speed the recovery and improve the prognosis. By definition, schizophreni-form disorder resolves within 6 months with a return to baseline mental functioning.




Hospitalization is often necessary and allows for effective as-sessment, treatment and supervision of a patient’s behavior. The psychotic symptoms, usually treated with a 3- to 6-month course of antipsychotic drugs, respond more rapidly than in patients with schizophrenia. One study found that 75% of the patients with schizophreniform psychosis compared with 20% of those with schizophrenia responded to antipsychotic agents within 8 days. ECT may be indicated for some patients, especially those with marked catatonic features or depression. If a patient has recurrent episodes, trials of lithium carbonate, valproic acid, or carbamazepine may be warranted for prophylaxis. Psychotherapy is usually necessary to help patients integrate the psychotic expe-rience into their understanding of their minds, brains and lives.


Delusional Disorder


Delusional disorder refers to a group of disorders, the chief feature of which is the presence of nonbizarre delusions. People suffer-ing from this illness do not regard themselves as mentally ill and actively oppose psychiatric referral. Because they may experience little impairment, they generally remain outside hospital settings, appearing reclusive, eccentric, or odd, rather than ill. They are more likely to have contacts with professionals such as lawyers and other medical specialists for health concerns. The current shift in diagnosis from paranoid to delusional helps avoid the ambiguity around the term “paranoid”. This also emphasizes that other delusions besides the paranoid ones are included in this di-agnosis. It is important to understand the definition of nonbizarre delusion so as to reach an unambiguous diagnosis. Nonbizarre delusions typically involve situations or circumstances that can occur in real life (e.g., being followed, infected, or deceived by a lover) and are believable.


Diagnostic Criteria


According to DSM-IV-TR, the diagnosis of delusional disorder can be made when a person exhibits nonbizarre delusions of at least 1 month’s duration that cannot be attributed to other psychi-atric disorders. Nonbizarre delusions must be about phenomena that, although not real, are within the realm of being possible. Ingeneral, the patient’s delusions are well systematized and have been logically developed. If the person experiences auditory or visual hallucinations, they are not prominent except for tactile or olfactory hallucinations where they are tied in to the delusion (e.g., a person who believes that he emits a foul odor might ex-perience an olfactory hallucination of that odor). The person’s behavioral and emotional responses to the delusions appear to be appropriate. Usually the person’s functioning and personality are well preserved and show minimal deterioration if at all.




Though the existence of delusional disorder has been known for a long time, relatively little is known about the demographics, incidence and prevalence. Unfortunately, people suffering from this illness function reasonably well in the community and lack insight resulting in minimal or no contact with the mental health system. However, the crude incidence is roughly 0.7 to 3.0 per 100 000 with a more frequent occurrence in females.




Etiology of the delusional disorder is unknown. Risk factors associated with the disorder include advanced age, sensory im-pairment/isolation, family history, social isolation, personality features (e.g. unusual interpersonal sensitivity) and recent im-migration. Some have reported higher association of delusional disorder with widowhood, celibacy and history of substance abuse. Age of onset is later than schizophrenia and earlier in men compared with women.




Persecutory Type


This is the most common form of delusional disorder. Here the person affected believes that he or she is being followed, spied on, poisoned or drugged, harassed, or conspired against. The person affected may become preoccupied by small slights that can become incorporated into the delusional system. These indi-viduals may resort to legal actions to remedy perceived injustice. Individuals suffering from these delusions often become resent-ful and angry with a potential to become violent against those believed to be against them.


Jealous Type


Individuals with this subtype have the delusional belief that their spouses/lovers are unfaithful. This is often wrongly inferred from small bits of benign evidence which is used to justify the delusion. Delusions of infidelity have also been called conjugal paranoia. The term Othello syndrome has been used to describe morbid jealousy. This delusion usually affects men, with no history of prior psychiatric problems. The condition is difficult to treat and may diminish only on separation, divorce or death of the spouse. Marked jealousy (pathological jealousy or morbid jealousy) is a symptom of many disorders including schizophrenia and not unique to delusional disorder. Jealousy is a powerful emotion and when it occurs in delusional disorder or as part of another condi-tion, it can be potentially dangerous and has been associated with violence including suicidal and homicidal behavior.


Erotomanic Type


These patients have delusions of secret lovers. Most frequently, the patient is a woman, though men are also susceptible to these delusions. The patient believes that a suitor, usually more sociallyprominent than herself, is in love with her. This can become cen-tral focus of the patient’s existence and the onset can be sudden. Erotomania is also referred to as de Clerambault’s syndrome. Again, these delusions can occur as part of other disorders too. Generally women (but not exclusively so), unattractive in appear-ance, working at a lower-level jobs, who lead withdrawn, lonely single lives with few sexual contacts are reported to be more prone to develop this condition. They select lovers who are sub-stantially different from them. They exhibit what has been called paradoxical conduct, the delusional phenomenon of interpreting all denials of love no matter how clear as secret affirmations of love. Separation from the love object may be the only satisfac-tory means of intervention. When it affects men, it can manifest with more aggressive and possibly violent pursuit of love. Thus, such people are often in the forensic system. The object of ag-gression is often companions or protectors of the love object who are viewed as trying to come between the lovers. However, re-sentment and rage in response to an absence of reaction from all forms of love communication may escalate to a point that the love object may be in danger too.


Approximately 10% of stalkers have a primary diagnosis of erotomania. Menezies and colleagues (1995) conducted the first predictive study of violence among erotomanic males and found that serious antisocial behavior (a criminal history) unrelated to the delusion and concurrent multiple objects of fixations discrim-inated between the dangerous and the nondangerous men. In a review by Meloy (1996), if violence occurred the object of love was target at least 80% of the time. The next most likely target was a third party perceived as impeding access to the object. He referred to this latter behavior as triangulation. Triangulation when present in jealousy, whether delusional or not, is motivated by a perceived competition for the love object.


Somatic Type


Delusional disorder with somatic delusions has been called monosymptomatic hypochondriacal psychosis. This disorder differs from other conditions with hypochondriacal symptoms in degree of reality impairment Munro (1991) has described the largest series of cases and has used content of delusions to define three main types.


Delusions of Infestations (Including Parasitosis) Delu-sional parasitosis is one of the most common presentations of monohypochondriacal psychosis, which occurs in absence of other psychiatric illness. The onset is insidious and chronic.


Matchbox sign describes the common phenomenon that occurred not so long ago in patients suffering from this condition. During their clinic visit, the patient would present with peeled skin, and other substances connected to delusional thinking in an empty old-fashioned matchbox as evidence that they were infested with insects. Delusional parasitosis has been described in associa-tion with many physical illnesses such as vitamin B12 deficiency, pellagra, neurosyphilis, multiple sclerosis, thalamic dysfunction, hypophyseal tumors, diabetes mellitus, severe renal disease, hep-atitis, hypothyroidism, mediastinal lymphoma and leprosy. Use of cocaine and presence of dementia has also been reported.


Psychogenic parasitosis was also known as Ekbom’s syn-drome before being referred to as delusional parasitosis. Females experienced this disorder twice as often as males. Entomologists, pest control specialists and dermatologists had often seen the pa-tient before seen by a psychiatrist. All investigators have been impressed by the concurrent medical illnesses associated withthis condition. Others have attempted to distinguish between de-lusional and nondelusional aspects of presentation to establish clearer diagnosis and thus management.


Delusions of Dymorphophobia This condition includes de-lusions such as of misshapenness, personal ugliness, or exagger-ated size of body parts.


Delusions of Foul Body Odors or Halitosis This is also called olfactory reference syndrome.


The frequency of these conditions is low, but they may be under diagnosed because patients present to dermatologists, plas-tic surgeons and infectious disease specialists more often than to psychiatrists. Patients with these conditions do respond to pimoz-ide, a typical antipsychotic medication and also to SSRIs. Usually prognosis is poor without treatment. It affects both sexes equally. Suicide apparently motivated by anguish is not uncommon.


Grandiose Type


This is also referred to as megalomania. In this subtype, the cen-tral theme of the delusion is the grandiosity of having made some important discovery or having great talent. Sometimes there may be a religious theme to the delusional thinking such that the per-son believes that he or she has a special message from god.


Mixed Type


This subtype is reserved for those with two or more delusional themes. However, it should be used only where it is difficult to clearly discern one theme of delusion.


Unspecifi ed Type


This subtype is used for cases in which the predominant delu-sion cannot be subtyped within the above mentioned categories. A possible example is certain delusions of misidentification, for example, Capgras’s syndrome, named after the French psychia-trist who described the ‘illusions of doubles’. The delusion here is the belief that a familiar person has been replaced by an imposter. A variant of this is Fregoli’s syndrome where the delusion is that the persecutors or familiar persons can assume the guise of stran-gers and the very rare delusion that familiar persons could change themselves into other persons at will (intermetamorphosis). Each disorder is not only a rare delusion but is highly associated with other conditions such as schizophrenia and dementia.


Course and Prognosis


Though the onset can occur in adolescence, generally it begins from middle to late adulthood with variable patterns of course, including lifelong disorder in some cases. Delusional disorder does not lead to severe impairment or change in personality, but rather to a gradual, progressive involvement with the delusional concern. Suicide has often been associated with this disorder. The base rate of spontaneous recovery may not be as low as pre-viously thought, especially because only the more severely af-flicted are referred for psychiatric treatment. The more chronic forms of the illness tend to have their onset early in the fifth dec-ade. Onset is acute in nearly two-thirds of the cases and gradual in the remainder. In almost half of the cases the delusion disap-pears at follow-up, improves in 10%, and is unchanged in 31%. In the more acute forms of the illness, the age of onset is in the fourth decade, a lasting remission occurs in over half of the pa-tients and a pattern of chronicity develops in only 10%; a relaps-ing course has been observed in 37%. Thus, the more acute and earlier the onset of the illness, the more favorable the prognosisThe presence of precipitating factors, married status and female gender are associated with better outcome. The persistence of delusional thinking is most favorable for cases with persecutory delusions and somewhat less favorable for delusions of grandeur and jealousy. However, the outcome in terms of overall function-ing appears somewhat more favorable for the jealous subtype.




Depression occurs frequently and is often an independent disor-der in these patients.




Though generally considered resistant to treatment and interven-tions, the management is focused on managing the morbidity of the disorder by reducing the impact of the delusion on the pa-tient’s (and family’s) life. However, in recent years the outlook has become less pessimistic or restricted in planning effective treatment for these conditions. An effective and therapeutic clini-cian–patient relationship is important but difficult to establish.


Somatic Treatment


Overall, treatment results suggest that 80.8% of cases recover either fully or partially. Pimozide, the most frequently reported treatment produced full remission in 68.5% and partial recovery in 22.4% (N 5 143). There are reports of treatment with other typical antipsychotic agents with variable success in small number of sub-jects. SSRIs have been used and reported to be helpful. The newer atypical antipsychotic agents have been used in small number of cases with success but the data is anecdotal. Bhatia and colleagues (2000) report that pimozide, fluoxetine and amitriptyline were used in their study with pimozide showing good response.


Psychosocial Treatment


As mentioned earlier, developing a therapeutic relationship is very important and yet significantly difficult, and requires a frank and supportive attitude. Supportive therapy is very helpful in deal-ing with emotions of anxiety and dysphoria generated because of delusional thinking. Cognitive therapy, when accepted and im-plemented, is helpful. Confrontation of the delusional thinking usually does not work and can further alienate the patient.


Shared Psychotic Disorder


Shared psychotic disorder is a rare disorder, which is also re-ferred to as shared paranoid disorder, induced psychotic dis-order, folie a deux and double insanity. In this disorder, the transfer of delusions takes place from one person to another. Both persons are closely associated for a long time and typically live together in relative social isolation. In its more common form, folie imposee, the individual who first has the delusion is often chronically ill and typically is the influential member of the close relationship with another individual, who is more suggestible and who develops the delusion too. The second indi-vidual is frequently less intelligent, more gullible, more passive, or more lacking in self-esteem than the primary case. If the two people involved are separated, the second individual may aban-don the delusion. However, this is not seen consistently. Other forms of shared psychotic disorder reported are folie simulta-nee, where similar delusional systems develop independently in two closely associated people. The most common dyadic rela-tionships who develop this disorder are sister–sister, husband– wife and mother–child. Almost all cases involve members of a single family




More than 95% of all cases of shared psychotic disorder involve two members of the same family. About a third of the cases involve two sisters, another one-third involve husband and wife or a mother and her child. The dominant person is usually af-fected by schizophrenia or a similar psychotic disorder. In 25% of all cases, the submissive person is usually affected with physical disabilities such as deafness, cerebrovascular diseases, or other disability that increases the submissive person’s dependence on the dominant person. This condition is more common in people from low socioeconomic groups and in women.




There is some data that suggest that people suffering from shared psychotic disorder may have a family history of schizophrenia. The dominant person suffering from this illness often has schiz-ophrenia or a related psychotic illness. The dominant person is usually older, more intelligent, better educated and has stronger personality traits than the submissive person, who is usually de-pendent on the dominant person. The affected individuals usually live together or have an extremely close personal relationship, as-sociated with shared life experiences, common needs and hopes, and, often, a deep emotional rapport with each other. The relation-ship between the people involved is usually somewhat or com-pletely isolated from external societal cultural inputs. The sub-missive person may be predisposed to a mental disorder and may have a history of a personality disorder with dependent or sug-gestible qualities as well as a history of depression, suspiciousness and social isolation. The dominant person’s psychotic symptoms may develop in the submissive person through the process of iden-tification. By adopting the psychotic symptoms of the dominant person, the submissive person gains acceptance by the other.




An important feature in the diagnosis is that the person with shared psychotic disorder does not have a preexisting psychotic disorder. The delusions arise in the context of a close relationship with a person who suffers from delusional thinking and resolve on separation from that person.


Clinical Features


The key symptom of shared psychosis is the unquestioning ac-ceptance of another person’s delusions. The delusions themselves are often in the realm of possibility and usually not as bizarre as those seen in patients with schizophrenia. The content of the delusion is often persecutory or hypochondriacal. Symptoms of a coexisting personality disorder may be present, but signs and symptoms that meet criteria for schizophrenia, mood disorders and delusional disorder are absent. The patient may have ideation about suicide or pacts about homicide; clinicians must elicit this information during the interview.


Differential Diagnosis


Malingering, factitious disorder with predominantly psychologi-cal sign and symptoms, psychotic disorder due to a general medi-cal condition and substance-induced psychotic disorder must be considered.


Course and Prognosis


Though separation of submissive person from the dominant per-son should resolve the psychosis, this probably occurs only in 10 to 40% of the cases. Unfortunately, when these individuals are discharged from hospital, they usually move back together.




The initial step in treatment is to separate the affected person from the source of the delusions, the dominant individual. An-tipsychotic agents may be used if the symptoms have not abated in a week after separation. Psychotherapy with the nondelusional members of the patient’s family should be undertaken, and psy-chotherapy with both the patient and the person sharing the delu-sion may be indicated later in the course of treatment. To prevent redevelopment of the syndrome the family may need family ther-apy and social support to modify the family dynamics and to pre-vent redevelopment of the syndrome. Steps to decrease the social isolation may also help prevent the syndrome from reemerging.


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