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Delusion Definition and Types

Delusion Definition and Types

A delusion is an unshakeable belief (we cannot change it with logical explanations or evidence) that is held on inadequate grounds (they do not have a valid explanation or evidence for their belief, and that is not a conventional belief that the person might be expected to hold given their educational, cultural, and religious background.  

Illusions are mostly but not always normal. Hallucinations are mostly but not always abnormal. But a delusion is something that is always abnormal. So, someone who believes to be possessed by the supernatural is not delusional because it’s a cultural common belief. In the west, many young girls become convinced that they need to be thin and take extreme measures, and their weight may reach life-threatening low levels and continue. And this is still not a delusion because they consider thinness socially desirable and they educate most people about the risks of obesity is dangerous and the need for thinness.

Persecutory delusions are the most common ones, in which they develop a belief that someone wants to harm them.

Common Types of Delusions

A delusion may be primary or secondary. Primary delusions occur out of the blue, unexplainable by the patient's morbid experiences at the time. Secondary delusions arise occur against a background. For example, a patient with mania and grandiosity develops grandiose delusions. 

A delusional disorder is characterised by a single delusion or delusional system that persists for at least three months. Most of the time, these are persecutory delusions; delusions of jealousy, Foli a deux or Fregoli delusions may also occur.  In schizophrenia, delusions are more likely to be bizarre, primary, multiple and non-systematized. Grandiose delusion is more characteristic of mania. Patients with depression often have cotard delusions, delusions of poverty or hypochondriacal delusions. 


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