The lifetime prevalence of delusional disorder has been estimated at around 0.2%, and the most frequent subtype is persecutory. Delusional disorder, jealous type, is probably more common in males than in females, but there are no major gender differences in the overall frequency of delusional disorder.
On average, global function is generally better than that observed in schizophrenia. Al- though the diagnosis is generally stable, a proportion of individuals go on to develop schizophrenia. Delusional disorder has a significant familial relationship with both schizophrenia and schizotypal personality disorder. Although it can occur in younger age groups, the condition may be more prevalent in older individuals.
ing the possible presence of delusional disorder. The content of delusions also varies across cultural contexts.
Functional Consequences of Delusional Disorder
The functional impairment is usually more circumscribed than that seen with other psy- chotic disorders, although in some cases, the impairment may be substantial and include poor occupational functioning and social isolation. When poor psychosocial functioning is present, delusional beliefs themselves often play a significant role. A common character- istic of individuals with delusional disorder is the apparent normality of their behavior and appearance when their delusional ideas are not being discussed or acted on.
Obsessive-compulsive and related disorders. If an individual with obsessive—compul— sive disorder is completely convinced that his or her obsessive-compulsive disorder beliefs are true, then the diagnosis of obsessive-compulsive disorder, with absent insight/delu- sional beliefs specifier, should be given rather than a diagnosis of delusional disorder.
Similarly, if an individual with body dysmorphic disorder is completely convinced that his or her body dysmorphic disorder beliefs are true, then the diagnosis of body dysmor- phic disorder, with absent insight/ delusional beliefs specifier, should be given rather than a diagnosis of delusional disorder.
Delirium, major neurocognitive disorder, psychotic disorder due to another medical con- dition, and substance/medication-induced psychotic disorder. Individuals with these disorders may present with symptoms that suggest delusional disorder. For example, sirn- ple persecutory delusions in the context of major neurocognitive disorder would be di- agnosed as major neurocognitive disorder, with behavioral disturbance. A substance/ atology to delusional disorder but can be distinguished by the chronological relationship of substance use to the onset and remission of the delusional beliefs.
Schizophrenia and schizophreniform disorder. Delusional disorder can be distinguished from schizophrenia and schizophreniform disorder by the absence of the other character- istic symptoms of the active phase of schizophrenia.
Depressive and bipolar disorders and schizoaffective disorder. These disorders may be distinguished from delusional disorder by the temporal relationship between the mood disturbance and the delusions and by the severity of the mood symptoms. If delusions oc- cur exclusively during mood episodes, the diagnosis is depressive or bipolar disorder with psychotic features. Mood symptoms that meet full criteria for a mood episode can be su- perimposed on delusional disorder. Delusional disorder can be diagnosed only if the total duration of all mood episodes remains brief relative to the total duration of the delusional disturbance. If not, then a diagnosis of other specified or unspecified schizophrenia spec- trum and other psychotic disorder accompanied by other specified depressive disorder, unspecified depressive disorder, other specified bipolar and related disorder, or unspeci- fied bipolar and related disorder is appropriate.
Diagnostic Criteria 298.8 (F23)
A. Presence of one (or more) of the following symptoms. At least one of these must be (1). (2). 0r (3): 1. Delusions.
2. Hallucinations.
3. Disorganized speech (e.g., frequent derailment or incoherence).