DSM-IV-TR Diagnostic Criteria
Nonbizarre delusions (i.e., involving situations that occur in real life, such as being followed, poisoned, infected, loved at a distance, or deceived by spouse or lover, or having a disease) of at least 1 month's duration.
Criterion A for schizophrenia has never been met.
Note: Tactile and olfactory hallucinations may be present in delusional disorder if they are related to the delusional theme.
Apart from the impact of the delusion(s) or its ramifications, functioning is not markedly impaired and behavior is not obviously odd or bizarre.
If mood episodes have occurred concurrently with delusions, their total duration has been brief relative to the duration of the delusional periods.
The disturbance is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition.
Specify type (the following types are assigned based on the predominant delusional theme):
Erotomanic type: delusions that another person, usually of higher status, is in love with the individual
Grandiose type: delusions of inflated worth, power, knowledge, identity, or special relationship to a deity or famous person
Jealous type: delusions that the individual's sexual partner is unfaithful
Persecutory type: delusions that the person (or someone to whom the person is close) is being malevolently treated in some way
Somatic type: delusions that the person has some physical defect or general medical condition
Mixed type: delusions characteristic of more than one of the above types but no one theme predominates
(Reprinted, with permission, from the Diagnostic and Statistical Manual of Mental Disorders. 4th edn. Text Revision. Washington, DC: American Psychiatric Association, 2000)
The cause of delusional disorder is unknown. A very small proportion of the population (roughly 0.03%) experience persistent, relatively fixed delusions in the absence of the characteristic features of other psychotic disorders like schizophrenia.
Etiologic theories about the development of delusional disorder abound, but systematic study is sparse. Early concepts of etiology focused on the denial and projection of unacceptable impulses. Hence, as examples, homosexual attraction would be reformulated unconsciously to homosexual delusions or a belief in a love relationship with a famous person. Other theories focus on projection of unacceptable sexual and aggressive drives, leading to paranoid fears of others. These and other psychodynamic theories have certain heuristic appeal, but little systematic study has been done to support these conjectures.
Little is known about the genetics of delusional disorder. Family studies have suggested a decided lack of increased family history of psychotic or mood disorder.
Delusional disorder is characterized by nonbizarre delusions. Most often the delusional content appears possible, albeit far-fetched. For example, people with this condition may have fixed delusions that they are in an unrequited love relationship with a famous person or that they are being watched by the CIA, but not that their movements are being controlled by an external force. Persons with this condition may appear otherwise quite normal. They often hold jobs and may be married. The oddness and eccentricity of their beliefs and behavior may manifest itself only around the topic of the delusion.
The diagnosis of delusional disorder depends on the presence of nonbizarre delusions in the absence of meeting Criterion A for schizophrenia (see Chapter 16). Specifically, there should not be significant hallucinatory experiences, marked thought disorder, prominent negative symptoms, or psychosocial deterioration. Except for the behaviors associated with the delusions (e.g., delusional accusations of unfaithfulness in the spouse), the actions of the individual are not otherwise impaired. Although people with delusional disorder may have comorbid major depression or bipolar disorder, the delusions should be present at times when a mood disorder is not present and not just concurrently with an episode of depression or mania. Under these circumstances, however, care must be taken to distinguish this condition from schizoaffective disorder. Specifically, the symptoms must not meet criterion A of the schizophrenia diagnostic criteria.
Specific types of delusional disorder have distinguishing features. The most familiar is the so-called persecutory type, in which patients experience fixed (and often focal) paranoid delusions that other persons are intending to harm them in some way. These patients may believe that they are being watched or followed, or that malevolent parties are engaging in other persecutory or threatening behavior. The affected person will act in a way that is consistent with the content of the persecutory delusion but will otherwise be normal.
Another common variant is the jealous type. These patients exhibit delusional beliefs that their significant other is being unfaithful. As with the persecutory type, the plausible nature of the belief system may make it difficult to distinguish delusional beliefs from normal fears or real experiences. Patients with delusional disorder, jealous type, either have beliefs that cross the threshold of credibility or refuse to accept reasonable reassurances. For example, a 90-year-old man who believes that his 88-year-old wife is having sex regularly with young men may be suffering from delusional disorder.
In delusional disorder, erotomanic type (also referred to as de Clerambault syndrome), the delusion is that another person, usually someone who is famous or of higher social status, is in love with the affected individual. These beliefs may be highly elaborate, although plausibility is maintained. For example, a young woman with delusional disorder, erotomanic type, may travel around the country to attend the concerts of a famous performer. She may believe that the performer gives her secret signals during his concert that indicate his love. However, she also may believe that there is some external reason that he cannot express his love more directly, for example, because he is married, or has an ill mother, or some other reason. Persons with this condition seldom make direct contact with their paramour, although they may, occasionally, engage in more aggressive stalking behavior. Whenever the disorder occurs, it typically becomes the central focus of the person's life.
In the grandiose type of the disorder, the person experiences fixed, false beliefs of power (e.g., being the owner of a major corporation), money, identity (e.g., being the Prince of England), a special relationship with God (e.g., being Jesus Christ) or famous people, or some other distinguishing characteristic. These patients may be quietly psychotic but may come to treatment as a result of a contact with a government agency or other organization. For example, a person who believes that he is the President of the United States may be picked up trying to enter the grounds of the White House.
The somatic type of delusional disorder involves a fixed belief of some physical abnormality or characteristic. Distinguishing this disorder from simple hypochondriasis may be difficult and generally depends of the content of the belief and the degree to which the belief is held in spite of evidence to the contrary. People with somatoform disorders such as hypochondriasis or body dysmorphic disorder may have a fixed belief regarding a specific, serious, but plausible physical illness, such as cancer or AIDS. In hypochondriasis, these beliefs often relate to specific symptoms, such as pain, stiffness, or swelling. Patients with delusional disorder, somatic type, may have beliefs about other, more unusual conditions. These delusions may involve beliefs about contamination with toxic substances, infestations of insects or other vermin, foul body odors, malfunctions of specific body parts such as the liver or intestines, or other unusual content.
Finally, the mixed type of delusional disorder involves more than one of the types described above, without one taking prominence, and the unspecified type involves delusions that do not fall into one of the other categories. For example, the delusion of Capgras Syndrome is the belief that a familiar person has been replaced by an imposter.
Psychological testing will reveal the presence of the delusional psychotic material in these patients but, most often, little else. The cognitive impairments or social deterioration seen in schizophrenia are absent; if such impairments are present, the diagnosis of schizophrenia should be considered. Similarly, prominent mood symptoms might suggest a diagnosis of a psychotic mood disorder.
Laboratory Findings & Imaging
Neuroimaging data on delusional disorder are rare. Limited evidence indicates that persons with delusional disorder show reduced cortical gray matter and increased ventricular and sulcal size similar to that seen in schizophrenia. However, there has been little systemic study of this condition.
Occasionally, patients with delusional disorder will go on to develop schizophrenia. This is an exception, though; most patients maintain the delusional diagnosis. About half of patients recover fully and about one-third improve significantly. Only about 20% maintain the delusion indefinitely.
Differential Diagnosis (Including Comorbid Conditions)
The differential diagnosis of delusional disorder encompasses broad categories of disorders. For example, delusional thinking may occur in patients with other psychotic disorders such as schizophrenia, schizoaffective disorder, mood disorders (bipolar disorder, manic or depressed type or major depression) with psychotic features, psychotic disorders due to a general medical condition, or substance-induced psychotic disorder. In delusional disorder, however, important features of those conditions will be absent. For example, the prominent hallucinations, negative symptoms, thought disorder, or social deterioration consistent with schizophrenia are not present. Similarly, mood symptoms, if present, are not prominent. The delusional thinking should not be accounted for by the presence of a medical condition or substance, including substances of abuse. For example, a young patient with a history of stimulant abuse who exhibits paranoid ideation after a recent cocaine binge would not necessarily have delusional disorder.
A delusional diagnosis also may be easily confused with the obsessions of obsessive-compulsive disorder (OCD; see Chapter 21); however, in OCD the patient almost always has at least some insight into the exaggerated nature of the thoughts. Further, obsessions associated with OCD most often involve an inappropriate or exaggerated appraisal of a real threat. This could include a fear of contamination, loss of control of impulses, loss of important documents, and similar threats. When delusional disorder involves a fear of a specific threat, the fears are more typically paranoid or persecutory in nature.
Somatoform disorders such as hypochondriasis or somatization disorder are easily confused with delusional disorder, somatic type (see Chapter 22). As noted earlier, delusional disorder, somatic type, generally differs in both degree and type of belief. That is, in delusional disorder the beliefs are held tenaciously, and often will involve implausible content. Alternatively, people with body dysmorphic disorder often hold tenaciously to their preoccupation with a specific body part and are not easily dissuaded from the belief. In this case, the belief may seem like a delusion. The distinction is that the problem is perceptual, – i.e., is fixed on the appearance of a body part, and does not extend to other types of delusional beliefs.
Paranoid personality disorder also may be confused with delusional disorder (see Chapter 30). Two significant characteristics distinguish these disorders. In paranoid personality disorder, the hostility and paranoid thinking most often are generalized and affect multiple areas of the person's life. For example, the patient may be jealous of the spouse but also will exhibit hypersensitivity at work and in other areas. By contrast, the psychotic thoughts of delusional disorder usually are focused in a single area with remarkable preservation of other areas of thinking and functioning. Another feature distinguishing the disorders is the tenacity of the delusional belief. Persons with delusional disorder most often will maintain a stable but false belief system for long periods. Alternatively, the threatening beliefs of the person with paranoid personality disorder do not reach delusional proportions and often wax and wane in intensity.
The treatment of delusional disorder relies heavily on the use of antipsychotic drugs, particularly the atypical antipsychotics; however, little systematic study has examined the effectiveness of this approach. Pharmacotherapy should be undertaken with caution: Patients with delusional disorder are convinced of the delusional beliefs and will usually resist medication management. Drug treatment should only be undertaken in the context of an ongoing therapeutic relationship in which there has been an effort to establish rapport, collaboration, and shared goals. For example, it is of little use to try to convince patients who have persecutory delusions that medicine will help them by changing how they think about the feared situation. Patients may be willing to take a drug that will calm the anxiety that has resulted from the persecution. Pimozide has been recommended for this condition; however, systematic study of this approach is lacking.
Individual supportive psychotherapy as well as family therapy may also be required.
Complications/Adverse Outcomes of Treatment
The main complication of delusional disorder has to do with whether the affected person acts on the delusion in some way. Most people with this disorder lead quiet, uneventful lives otherwise. However, a sudden, unexpected event may intervene, such as the stalking of a famous person. These events may lead to incarceration or involuntary hospitalization, which may surprise friends and coworkers. These actions are consistent with the content of the delusion. Unfortunately, treatment, at least in the short term, often is ineffective, leading to a repetition of the behaviors related to the false beliefs.
The prognosis of delusional disorder is good in most cases. About two third of patients recover or improve significantly; however, in about 20% of patients delusional symptoms persist and are usually treatment-resistant.
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NL: Recent advances in the treatment of delusional disorder. Can J Psychiatry