Delusional disorder is rare and not much research data is known. The estimated incidence is about 1 to 3 cases per 100,000. people, with the female:male ratio being 3:1. The real incidence is unknown because of the possibility of under-reporting, as individuals would not volunteer this ordinarily but would have to be forced by their families to seek psychiatric help. Men tend to develop paranoid delusions and woman tend to develop erotomanic delusions. The onset of the disorder is often associated with a dramatic life event.
Delusional disorder differs from schizophrenia in the following ways. It is usually diagnosed later in life in middle age, the personality is intact and there is no functional decline. Schizophrenia is diagnosed in early adulthood, and is associated with personality and functional decline. In primary delusional disorder, there is an underlying psychiatric disorder such as depression, dememtia, organic brain pathology and intellectual disability.Secondary delusional disorder is due to an underlying medical or neurological condition. Examples include, leprosy, diabetes, hepatitis, hypetension, prostatic hypertrophy.
The causeof delusional disorder, as with all major psychiatric disorders, is unknown. It is much rarer than schizophrenia or mood disorders. There does seem to be a genetic cause. There is no link to schizophrenia or mood disorder.Risk factors for delusional disorder are the following:
The content of these delusions can be of any nature, and are usually non-bizarre and paranoid in nature. It can be mono-delusional or a complex organised delusional system. Non-bizarre means that it could be plaussable, that the situation could possibly really have occurred, such as being followed, loved at a distance
Common delusions involve erotomania and jealousy. Erotomania is the belief that someone, usually of the opposite sex and someone famous is in love with you. Delusions of jealousy or infidelity is the belief that your partner or spouse is being unfaithful.Apart from these beliefs, delusions could be of the following types:
The individual presents as quite organised and well groomed, with no evidence of functional disturbance. They seem slightly eccentric, suspicious or hostile. A feature of their presentation is that the whole examination will be normal except for the delusional ideation. Patients do not have prominent or sustained hallucinations. Patients with delusional disorder do not normally have insight into their illness and are brought to the clinicailns by police, employers or family.
Persecutory type is the most common type of delusional disorder. This is usually an ordered, systematised, logical delusion, with an intact personality and daily functioning.
Jealous type. The patient will have delusions of infidelity towards his partner. This often affects men. This symptom ca occur as part of a delusional disorder, or it can occur as part of a manic, depressive or schizophrenia disorder, or secondary to conditions discussed above.
This disorder is also called pathological jealousy or morbid jealousy, and is sometimes referred to as the Othelo syndrome. (The term Othello syndrome comes from a Shakespearian play in which a character in Othello kills his wife because he believes that she was unfaithful.) This is often the cause of marital stress and can lead to acts of hostility, aggression, stalking and violence. Partners can hire private detectives, accuse their partner's of infidelity, monitor their movements and constantly check up on them at work or other whereabouts. Physical and verbal abuse occur more frequently than extreme violence or homicide.
Erotomanic type. The incidence is unknown but it is rarer than delusional disorder. These patients believe that he or she is being loved from afar. As with all delusions, this belief is maintained despite evidence to the contrary, and the belief is out of context to the person's cultural, edicational and social background. This condition is more common in females than males.
Erotomania can occur as a primary disorder or can be classified as secondary to another psychiatric disorder or other brain pathology.
In erotomania the subject of the erotomanic delusions is usually someone of higher social status and may be married or otherwise unobtainable. The patient will often offer "irrefutable evidence" that this person is in love with them, and will interepret rejection as conclusive evidence that this person is indeed in love with them. The onset of this condition is often sudden.
The prototypical patient profile is usually female, not particularly attractive and of low status, and not in a relationship.
Men are affeted less frequently, but there is greater incidence of violence and aggression. The victim of the aggresive act may be the love object or their partner, who are seen as trying to disrupt the "love couple". Sometimes the love object may be the victim of aggression, if there is an absence of reaction. This condition can remain undiagnosed for many years and only come to the attention of authorities due to socially disruptive acts such as excessive telephoning, letter writing, SMSing or stalking, or sexual or non-sexual violence.
In delusions of the somatic type, the patient believes that they have a physical disorder. This differs from hypochondriasis in the intensity of their belief. In delusional disorder, the patient is absolutely convinced and unmoveable in their belief. In hypochondriasis, the patient can be challenged on their ideas.
There are 3 subtypes.In delusions of infestaion, the patient believes that they have an infestation.
These patients often present to other medical professionals first such as dermatologists, plastic surgeons or physicians.
Unspecified type is reserved for those delusions that cannot be characterised in the previous categories. Capgrass Syndrome is one such disorder which would fall within this category. This is the belief that someone close to you, usually a family member, is an imposter. This is named after a french psychiatrist who described the illusion of doubles. Sometimes there is a variation to this where family members can change into other people. This is a rare disorder and my be associated with other psychiatric disorders such as schizophrenia, dementia and epilepsy.
Over the years there has been a lot of pessimism about treatment success. It was thought that the disorder is unresponsive to medications. Over the last decade, there appears to be some optimism with treatment response reported in 50% of cases. However, this must be balanced against the following. There is a lack of double blind trials and most reportes are from case studies which is biased towards favourable results. There have been sporadic reports of success with the atypical antipsycotics and adherance might be the key factor in treatment success. previous poor treatment response may have been due to the traditional use of pimozide, a typical agent,as treatment for delusional disorder.
There has been success with pimozide with somatic delusions
More research on drug treatment is needed.
In erotomanic type delusion, the delusion may only regress if the patient is geographically removed from the love object.