Delusional disorder, previously called paranoid disorder, is a type of serious mental illness called a psychotic disorder.
People who have it can’t tell what’s real from what is imagined.
Delusions are the main symptom of delusional disorder. They’re unshakable beliefs in something that isn’t true or based on reality.
But that doesn’t mean they’re completely unrealistic. Delusional disorder involves delusions that aren’t bizarre, having to do with situations that could happen in real life, like being followed, poisoned, deceived, conspired against, or loved from a distance.
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These delusions usually involve mistaken perceptions or experiences. But in reality, the situations are either not true at all or highly exaggerated.
A bizarre delusion, by contrast, is something that could never happen in real life, such as being cloned by aliens or having your thoughts broadcast on TV. A person who has such thoughts might be considered delusional with bizarre-type delusions.
People with delusional disorder often can continue to socialize and function normally, apart from the subject of their delusion, and generally do not behave in an obviously odd or bizarre manner.
This is unlike people with other psychotic disorders, who also might have delusions as a symptom of their disorder. But in some cases, people with delusional disorder might become so preoccupied with their delusions that their lives are disrupted.
Although delusions might be a symptom of more common disorders, such as schizophrenia, delusional disorder itself is rather rare.
Delusional disorder most often happens in middle to late life and is slightly more common in women than in men.