Like schizophrenia, delusional disorder involves the presence of delusions that last for at least one month or longer. Delusions are fixed, mistaken ideas that the person holds. These are often odd or incorrect ideas about themselves and the world around them.
Unlike schizophrenia, however, hallucinations are either not present or are not prominent, unless related to the delusions. Delusional disorder also tends to start later in life than schizophrenia. Those with delusional disorder often are still able to care for themselves, work, have relationships and manage their daily lives.
For a diagnosis to be made, one or more delusions must be present for one month or longer.
The symptoms cannot be caused by another mental disorder or be the effects of a substance taken or other medical condition.
There are several subtypes that can be specified. These are made based on the main theme of the delusion(s) and include:
- Erotomanic type - when the delusion is that another person is in love with the individual (usually a famous person)
- Grandiose type - having the belief of having some great (but not recognized) talent or having made some important discovery
- Jealous type - believing that his or her spouse, partner or lover has been unfaithful
- Persecutory type - the individual believes that he or she is being plotted against, spied on, followed, poisoned or drugged, harassed, etc.
- Somatic type - the delusion involves bodily functions or sensations
- Mixed type - there is no one main theme of the delusion(s)
- Unspecified type - when the main belief of the delusion cannot be clearly determined or doesn't fit in the above types