The essential characteristic of delusional disorder is the presence of one or more delusions that persist for at least one month. During the 17th century, the concept of madness was primarily based on delirium, so “being crazy” was the same as “having delusions” and vice versa. So, what is a delusion?
The most well-known and cited definition is the one offered by Jaspers in his General Psychopathology (1975). For Jaspers, delusions are false judgments that are characterized by the fact that the individual holds them with great conviction, such that they are not influenced by experience or by irrefutable conclusions. In addition, their content is impossible.
To identify a delusion as such we should take into account the degree to which the experience fits the following points:
- He stands by it with absolute conviction.
- It is experienced as a self-evident truth, with great personal significance.
- It cannot be modified by reason or experience.
- Its content is often fantastic or at least inherently improbable.
- It is not shared by other members of the social or cultural group.
- The person is preoccupied with the belief and finds it difficult to avoid thinking or talking about it.
- The belief is a source of subjective discomfort or interferes with the person’s social functioning and occupations.
In short, delusions are characterized by being conceptually very complex, and perhaps that is why it is so difficult to “enclose” them in a definition. Nowadays, if we were to ask any person to describe their prototypical image of a “madman,” they would most likely tell us that it is someone who believes himself to be Napoleon or who claims that Martians are chasing him.
What are the characteristics of delusional disorder?
As we said before, the fundamental characteristic of delusional disorder is the presence of one or more delusions that persist for at least one month. We should not confuse the presence of delusions with the diagnosis of schizophrenia. Delusional disorder is one thing and schizophrenia is another.
The diagnosis of delusional disorder is not made if the person has ever had a clinical presentation that meets criterion A for schizophrenia (according to the DSM-5 ). Apart from the direct impact produced by delusions, the impairment of psychosocial functioning may be more circumscribed than in other psychotic disorders.
Additionally, a person with delusional disorder does not behave in bizarre or unusual ways, as might occur in other psychotic disorders. The DSM-5 also reflects that in delusional disorder, the delusions cannot be attributed to the effects of a substance (e.g., cocaine) or another medical condition (e.g., Alzheimer’s disease ). They also cannot be better explained by another mental disorder, such as body dysmorphic disorder or obsessive-compulsive disorder.
Diagnostic criteria for delusional disorder according to DSM-5
The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) lists the following diagnostic criteria for delusional disorder. They are as follows:
A. Presence of one or more delusions lasting one month or more.
B. Criterion A for schizophrenia has never been met. Hallucinations, if present, are not prominent and are related to the delusional theme (e.g., a feeling of being infested by insects associated with delusions of infestation).
C. Apart from the impact of the delirium or its ramifications, functioning is not significantly impaired and behavior is not grossly bizarre or unusual.
D. If manic or major depressive episodes have occurred, they have been brief compared with the duration of the delusional periods.
E. The disturbance cannot be attributed to the physiological effects of a substance or another medical condition. It is not better explained by another mental disorder, such as body dysmorphic disorder or obsessive-compulsive disorder.
What types of delusions exist?
Again, the DSM-5 lists the types of delusions that exist. The following delusions may occur in a delusional disorder:
- Erotomanic type. The central theme of the delusion is that another person is in love with the individual suffering from the disorder.
- Type of greatness. The central theme of the delusion is the belief of having some (unrecognized) talent or knowledge or of having made some important discovery.
- Jealous type. This subtype applies when the central theme of the delusion is that one’s spouse or lover is unfaithful.
- Persecutory type. The central theme of the delusion involves the belief that one is being conspired against, deceived, spied on, followed, poisoned, drugged, defamed, harassed, or otherwise prevented from achieving long-term goals.
- Somatic type. It is applied when the central theme of delirium involves bodily functions or sensations.
In addition to these types, there is also the mixed type (considered when no type of delusion predominates) and the unspecified type. The latter is applied when the dominant delusion cannot be determined or is not described in the specific types (e.g., referential delusions without a significant persecutory or grandiose component).
Treatment of delusional disorder
Delusional disorder is considered difficult to treat. Antipsychotic drugs, antidepressants, and mood-stabilizing drugs are frequently used to treat psychotic disorders. There is also a growing interest in psychological therapies as forms of treatment. On the other hand, we can say that there is still much room for improvement in interventions for delusional disorders at present.
Currently, there is no single form of intervention that stands out from the others in terms of the results it achieves. Until a specific intervention is identified that improves the results of general interventions, treatment for delusional disorders will probably be based on those considered effective for other psychotic disorders and mental health problems.