Delusional Disorder

Primer

Delusional disorder is a mental disorder characterized by the presence of one or more delusions that persist for at least 1 month. A diagnosis of delusional disorder is not given if an individual has ever had symptoms that meet criteria for schizophrenia. Apart from the direct impact of the delusions, impairments in psychosocial functioning may be minor compared to those seen in other psychotic disorders such as schizophrenia.

Epidemiology
  • The lifetime prevalence of delusional disorder has been estimated at around 0.2%, and the most frequent subtype is persecutory.[1]
  • There are no major gender differences in the overall frequency of delusional disorder.
    • Delusional disorder, jealous type, is probably more common in males than in females.[2]
Prognosis
Comorbidity
Risk Factors
  • Immigration, isolation, family history, sensory impairment, and advanced age are risk factors for delusional disorder.[4][5]

DSM-5 Diagnostic Criteria

Criterion A

The presence of at least 1 delusion with a duration of at least 1 month.

Criterion B

Criterion A for schizophrenia has never been met.

Note: Hallucinations, if present, are not prominent and are related to the delusional theme (e.g. - the sensation of being infested with insects associated with delusions of infestation).
Criterion C

Apart from the impact of the delusion(s) or its ramifications, functioning is not markedly impaired, and behaviour is not obviously bizarre or odd.

Criterion D

If manic or major depressive episodes have occurred, these have been brief relative to the duration of the delusional periods.

Criterion E

The disturbance is not attributable to the physiological effects of a substance or an other medical condition and is not better explained by another mental disorder, such as body dysmorphic disorder or obsessive-compulsive disorder.

Specifiers

Specifiers

Specify whether:

  • Erotomanic type: This subtype applies when the central theme of the delusion is that another person is in love with the individual.
  • Grandiose type: This subtype applies when the central theme of the delusion is the conviction of having some great (but unrecognized) talent or insight or having made some important discovery.
  • Jealous type: This subtype applies when the central theme of the individual’s delusion is that his or her spouse or lover is unfaithful.
  • Persecutory type: This subtype applies when the central theme of the delusion involves the individual’s belief that he or she is being conspired against, cheated, spied on, followed, poisoned or drugged, maliciously maligned, harassed, or obstructed in the pursuit of long-term goals.
  • Somatic type: This subtype applies when the central theme of the delusion involves bodily functions or sensations.
  • Mixed type: This subtype applies when no one delusional theme predominates.
  • Unspecified type: This subtype applies when the dominant delusional belief cannot be clearly determined or is not described in the specific types (e.g. - referential delusions without a prominent persecutory or grandiose component).
  • With bizarre content: Delusions are deemed bizarre if they are clearly implausible, not understandable, and not derived from ordinary life experiences (e.g. - an individual’s belief that a stranger has removed his or her internal organs and replaced them with some one else’s organs without leaving any wounds or scars).

Severity Specifier

Specify current severity:

  • Severity is rated by a quantitative assessment of the primary symptoms of psychosis, including delusions, hallucinations, disorganized speech, abnormal psychomotor behavior, and negative symptoms. Each of these symptoms may be rated for its current severity (most severe in the last 7 days) on a 5-point scale ranging from 0 (not present) to 4 (present and severe)
  • Note: Diagnosis of delusional disorder can be made without using this severity specifier

Treatment

Delusional disorder is highly resistant to treatment with medication alone.[6]

Differential Diagnosis

  • CNS Neoplasms[7]

Comparison of Psychotic Disorders

The term psychosis has been defined in various ways in the medical literature over time. The narrowest and current definition of psychosis is hallucinations and delusions, with the lack of reality testing or insight. A broader definition of psychosis would also include disorganized thought, emotions, and behaviour. This loose definition was more common in the past, and schizophrenia was often overdiagnosed as a result.

DSM-IV to DSM 5 Psychotic Disorder Criteria Changes

Substance Abuse and Mental Health Services Administration. Table 3.20, DSM-IV to DSM-5 Psychotic Disorders

Comparison of Psychotic Disorders

Type Onset Length Psychotic Symptoms Mood Symptoms Functional Decline?
Brief psychotic disorder Sudden 1 day to 1 month At least 1 of:
• Delusions
• Hallucinations
• Disorganized speech
• Grossly disorganized or catatonic behaviour 		No Full resolution of symptoms
Schizophreniform disorder Can be prodromal 1 month to 6 months At least 2 of:
• Delusions
• Hallucinations
• Disorganized speech
• Grossly disorganized or catatonic behaviour
• Negative symptoms 		No Not required
Schizophrenia Can be prodromal > 6 months At least 2 of:
• Delusions
• Hallucinations
• Disorganized speech
• Grossly disorganized or catatonic behaviour
• Negative symptoms 		No Required
Schizoaffective disorder Can be prodromal Major mood episode
+ 2 weeks of isolated psychotic symptoms + predominantly mood symptoms over course of illness 		• Delusions or hallucinations for 2 or more weeks, which must be in absence of a major mood episode (depressive or manic) during the lifetime duration of the illness Required Not required
Delusional disorder Can be prodromal > 1 month • One or more delusions, with no other psychotic symptoms. No Normal function aside from impact of delusions

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References

1) American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). Arlington, VA.
2) American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). Arlington, VA.
3) K⊘ rner, A., Lopez, A. G., Lauritzen, L., Andersen, P. K., & Kessing, L. V. (2008). Delusional disorder in old age and the risk of developing dementia–a nationwide register-based study. Aging and Mental Health, 12(5), 625-629.
4) Joseph, S. M., & Siddiqui, W. (2020). Delusional Disorder. StatPearls [Internet].
5) Tampi, R. R., Young, J., Hoq, R., Resnick, K., & Tampi, D. J. (2019). Psychotic disorders in late life: a narrative review. Therapeutic advances in psychopharmacology, 9, 2045125319882798.
6) Cleveland Clinic: Delusional Disorder
7) Stupinski, J., Kim, J., & Francois, D. (2017). Delusional Disorder Arising From a CNS Neoplasm. The Journal of neuropsychiatry and clinical neurosciences, 29(2), 186-188.