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Delusional disorder

This topic covers about Delusional disorder, Symptoms, Diagnosis and Treatment.

Delusional disorder

Delusional disorder is classified as a psychotic disorder, a disorder where a person has trouble recognizing reality. Person cannot tell what is real from what is imagined.  A delusion is a false belief that is based on an incorrect interpretation of reality.  Delusions, like all psychotic symptoms, can occur as part of many different psychiatric disorders.  But the term delusional disorder is used when delusions are the most prominent symptom and characterized by the presence of recurrent, persistent non-bizarre delusions, which involve situations that could occur in real life such as being followed, poisoned, deceived, conspired against, or loved from a distance.  Non-bizarre delusions are considered to be plausible; that is, there is a possibility that what the person believes to be true could actually occur in a small proportion of situations.  These delusions usually involve the misinterpretation of perceptions or experiences.  In reality, the situations are either not true at all or highly exaggerated.  The incidence and prevalence of the disease remained more or less static over the years because of the low levels of case finding and treatment completion, leading to practically no epidemiological impact.


  • The prevalence is estimated at 0.025-0.03%, lower than the rates for schizophrenia (1%).
  • Delusional disorder may account for 1–2% of admissions to inpatient psychiatric hospitals.
  • Age at onset ranges from 18–90 years, with a mean age of 40 years.
  • More females than males (overall) suffer from delusional disorder.
  • Delusional disorder is typically a chronic (ongoing) condition, but when properly treated, many people with this disorder can find relief from their symptoms.
  • Some people recover completely and others experience episodes of delusional beliefs with periods of remission.
  • Unfortunately, many people with this disorder do not seek help.
  • It is often difficult for people with this mental disorder to recognize that they are not well.
  • They also might be too embarrassed or afraid to seek treatment.
  • Without treatment, delusional disorder can be a life-long illness.
  • Early diagnosis and treatment can help decrease the disruption to the person's life, family and friendships.


No specific lab test is followed for diagnosis. Careful and detailed history from the client helps in identification of delusional disorder.  Psychiatrists use specially designed interview and assessment tools to evaluate the disorder. The diagnosis is made on the basis of person's report of symptoms, and observation of the person's attitude and behaviour.  Clients' past medical records and discussion with family members also help to confirm the diagnosis. Delusions are often observed in persons with other psychotic disorders such as schizophrenia and schizoaffective disorder. In addition to occurring in the psychotic disorders, delusions also may be evident as part of a response to physical, medical conditions such as brain injury or brain tumours, or reactions to ingestion of a drug.  Because delusions can be shown as part of many illnesses, the diagnosis of delusional disorder is partially conducted by process of elimination.


  • The presence of non-bizarre delusions is the most obvious symptom of this disorder.
  • An irritable, angry or low mood.
  • People with delusional disorder often can continue to socialize and function normally, apart from the subject of their delusion.
  • Generally do not behave in an obviously odd or bizarre manner. Hallucinations are usually absent but sometimes they are present in relation to their delusion.
  • In some cases, however, people with delusional disorder might become so preoccupied with their delusions that their lives are disrupted.

Sub Types

  • Erotomanic: Someone with this type of delusional disorder believes that another person, often someone important or famous, is in love with him or her. The person might attempt to contact the object of the delusion, and stalking behaviour is not uncommon.
  • Grandiose: A person with this type of delusional disorder has an over-inflated sense of worth, power, knowledge or identity. The person might believe he or she has a great talent or has made an important discovery.
  • Jealous: A person with this type of delusional disorder believes that his or her spouse or sexual partner is unfaithful. Patients are firmly convinced of the infidelity of a spouse or partner, despite contrary evidence. In some instances, some degree of infidelity may actually be occurring, yet the magnitude of the jealous response and the evidence accumulated to support the unfaithfulness may take a delusional quality.  Based on minimal data like finding an unidentified number on mobile, messy bed sheet etc they may try to constrict their partners' activities or confine them to home. This sub type of delusional disorder is most commonly associated with aggression and violence and can sometimes lead to murder of partner.
  • Persecutory: People with this type of delusional disorder are convinced that they (or someone close to them) are being malevolently treated or harmed in some way. These persecutory beliefs are often associated with querulousness, irritability, anger and at times aggressive or even homicidal behaviour. It is not uncommon for people with this type of delusional disorder to make repeated complaints to legal authorities.
  • Somatic: A person with this type of delusional disorder believes that he or she has a physical defect or medical problem.
  • Mixed: People with this type of delusional disorder have two or more of the types of delusions listed above.
  • Etiology: As with many other psychotic disorders, the exact cause of delusional disorder is not yet known. Researchers are, however, looking at the role of various genetic, biological, and environmental or psychological factors.
  • Genetic: The fact that delusional disorder is more common in people who have family members with delusional disorder or schizophrenia suggests there might be a genetic factor involved. It is believed that, as with other mental disorders, a tendency to develop delusional disorder might be passed on from parents to their children.
  • Biological: Researchers are studying how abnormalities of certain areas of the brain might be involved in the development of delusional disorders. An imbalance of certain chemicals in the brain, called neurotransmitters, also has been linked to the formation of delusional symptoms. An imbalance in these chemicals can interfere with the transmission of messages, leading to symptoms.
  • Environmental/psychological: Evidence suggests that delusional disorder can be triggered by stress. Alcohol and drug abuse also might contribute to the condition. People, who tend to be isolated, such as immigrants or those with poor sight and hearing, appear to be more vulnerable to developing delusional disorder.

Effect of Delusional disorder

  • People with delusional disorder might become depressed, often as the result of difficulties associated with the delusions.
  • Acting on the delusions also can lead to violence or legal problems; for example, a person with an erotomanic delusion who stalks or harasses the object of his or her delusion, could lead to arrest.
  • Persecutory and jealous sub types may lead to aggression and homicidal behaviour.
  • People with this disorder can eventually become alienated from others, especially if their delusions interfere with or damage their relationships.


Treatment for delusional disorder most often includes medication and psychotherapy. Delusional disorder is highly resistant to treatment with medication alone. The primary drugs used to treat delusional disorder are called antipsychotics. Newer second generation antipsychotics appear to be more effective in treating symptoms of delusional disorder. Other medications like tranquilizers and antidepressants are also used to treat associated anxiety or depression. Psychosocial treatment can help with the behavioural and psychological problems associated with delusional disorder. Through therapy, patients also can learn to control their symptoms, identify early warning signs of relapse, and develop a relapse prevention plan. Cognitive-behavioural therapy (CBT) can help the person learn to recognize and change thought patterns and behaviours that lead to troublesome feelings. Cognitive therapy has shown promise as an emerging treatment for delusions. Family therapy can help families to deal more effectively with a loved one who has delusional disorder, enabling them to contribute to a better outcome for the person.

Source : Kaplan & Sadock’s Comprehensive text book of psychiatry. Volume I Ninth edition

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