Delusional Disorder

Delusion(s) that persist for at least one month- without any other features of Schizophrenia (or mood disorder), and do not impair psychosocial functioning except from the ramifications of the delusion(s).


  • Less common than schizophrenia (around 0.02% prevalence) and tends to occur in middle to late adult life
  • There tends not to be a large impact on daily living as with schizophrenia


  • May arise from a pre-existing personality disorder (paranoid or schizo-affective type)
  • Delusion(s) can, in theory, be anything, although several subtypes are more common
    • Erotomanic type- delusions that another person is in love with them
    • Grandiose type- delusions of inflated worth, power, knowledge, identity, or special relationships to a deity or famous person/people
    • Jealous type- delusions of unfaithfulness, jealousy
    • Persecutory type- delusions that they (or someone close to them) is being malevolently treated in some way
    • Somatic type- delusions that they have a physical defect or medical condition
  • Delusions can be mixed type or unspecified
  • In general, patients have poor insight into their delusions

Note: it is important to differentiate between a delusion (firmly held unreasonable belief) and an over-valued idea (can be unreasonable but is rarely so firmly held).  Cultural/religious beliefs must be carefully considered.


  • If possible/suitable- psychotherapy (supportive therapy and/or cognitive therapy) is the most effective treatment
    • There is little evidence to support the use of pharmacological treatments, although atypical antipsychotic medications may be tried in some cases.

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