Delusional disorder is characterized by the presence of either bizarre or non-bizarre delusions which have persisted for at least one month. Non-bizarre delusions typically are beliefs of something occurring in a person’s life which is not out of the realm of possibility. For example, the person may believe their significant other is cheating on them, that someone close to them is about to die, a friend is really a government agent, etc. All of these situations could be true or possible, but the person suffering from this disorder knows them not to be (e.g., through fact-checking, third-person confirmation, etc.). 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 someone else’s organs without leaving any wounds or scars). Delusions that express a loss of control over mind or body are generally considered to be bizarre and reflect a lower degree of insight and a stronger conviction to hold such belief compared to when they are non-bizarre. Accordingly, if an individual has bizarre delusions, a clinician will specify “with bizarre content” when documenting the delusional disorder.
People who have this disorder generally don’t experience a marked impairment in their daily functioning in a social, occupational, or other important setting. Outward behavior is not noticeably bizarre or objectively characterized as out-of-the-ordinary.
The delusions can not be better accounted for by another disorder, such as schizophrenia, which is also characterized by delusions (which are bizarre). The delusions also cannot be better accounted for by a mood disorder, if the mood disturbances have been relatively brief. The lifetime prevalence of delusional disorder has been estimated at around 0.2%.
Specific Diagnostic Criteria
- Delusions lasting for 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. Criterion A of schizophrenia requires two (or more) of the following, each present for a significant portion of time during a 1-month period (or less if successfully treated):
- disorganized speech (e.g., frequent derailment or incoherence)
- grossly disorganized or catatonic behavior
- negative symptoms, i.e., affective flattening, alogia, or avolition
Note: Criteria A of schizophrenia requires only one symptom if delusions are bizarre or hallucinations consist of a voice keeping up a running commentary on the person’s behavior or thoughts, or two or more voices conversing with each other.
- 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
- Unspecified Type
For more on treatment, please see treatment for delusional disorder.
This entry has been updated for 2013 DSM-5 criteria; diagnostic code: 297.1.