There are three components to the definition of a delusion:
- the delusion is a belief which is held on unsatisfactory grounds
- a delusion is not amenable to rational arguement
- a delusion is not explicable in terms of the social or cultural background of the patient
A delusion is usually, but not always, a false belief.
A delusional belief may dominate the life of the patient e.g. a persecutory delusion may prevent the patient leaving their home. Alternatively, the patient may appear unmoved by what would seem to be a terrifying belief, this picture is most common in patients with chronic schizophrenia.
Delusions may be primary or secondary.