What is a delusion?

A delusion is a belief that is false and lacking in any supporting evidence. The affected person is convinced and holds on to this belief firmly despite evidence or past experiences pointing to the contrary. People with delusion often misinterpret or highly exaggerate experiences and perception such that everything is relatable and concerned with them.

There are many types of delusion, classified according to their content, here are a few examples:


Delusion of Reference

This is the most common form of delusion seen in people with schizophrenia, thus it is often a warning sign for prodrome for psychosis and its relapse. The patient believes that the surroundings have a special message for him. Examples of this are people on television or blogs talking about him; gestures of strangers having ‘hidden messages’ contained that only he can perceive, or particular actions from strangers purposely annoying him.



- Capgras syndrome where the patient believes that one of his family members has been replaced by an identical impostor, or

- Fregoli syndrome where a family member is disguised as a stranger.


Being controlled

The patient believes that his thoughts, his actions and his speech are under the control of external forces and he has no control over it. The patient anticipates the forces are from the spiritual world, for example they believe the evil spirits are moving his/her shoulder, or God is controlling his/her arm.



People with delusion may also hold beliefs that they have a medical condition or a serious disease. They are obsessed with this idea that their illness is not yet diagnosed even though no medical evidence to support this. Some of them may also deny the existence of certain things there is in the real world.


Delusion of persecution

The patient believes that he has been targeted by others, often ‘they’ are ‘after him’ to harm him.


Delusion of grandeur

The patient has a false belief that he/she is ‘special’; (They may be famous, have special powers or wealth. For example, the patient may believe they have a close relationship with a very prominent person.


Thought block, insertion, withdrawal

The patient has the idea where someone else can think through the person’s mind, placing thoughts into their head, stopping thoughts or thoughts are being ‘taken’ from their head.


Psychiatrists have gathered their clinical experiences, their understanding for delusions and speculations in attempt to explain this disorder, and the following are a few of the theories mentioned:


Attributional bias

A negative event widens the gap between our ideal self and the reality. Self-serving bias is a cognitive error which the person attribute their failure to external forces, rather than accepting personal responsibility. The tendency to hold self-serving bias is particularly severe in deluded patients.


Probabilistic reasoning

Patient may show a ‘jumping to conclusion’ style of probabilistic reasoning even when there isn’t enough information.


Aberrant salience

Due to the huge amount of information that surrounds us in our daily environment, not all information exchanged will be registered into our conscious mind. The more relevant and significant the information we receive, the more activated our dopaminergic system becomes, resulting in ‘salience’. When chaotic dopamine firing occurs, stimuli that would normally be considered irrelevant becomes ‘salient’. As a result, when the person is experiencing aberrant salience, there is a greater likelihood of developing delusions.


Studies have shown that around half of those with delusion will carry out subsequent actions, mostly defensive actions for him/herself or others; people with delusion are not usually violent. It may be difficult for the patients’ family and friends to understand the patient at times, as the delusional thoughts can be very incomprehensible; Even when family and friends refute the delusions with logic and evidence, the patient will remain adamant and is unable to accept another explanation. We must understand that these delusional thoughts are brought on by the illness, and therefore avoid arguing with the patient. The patient’s delusion can affect the emotional well being of the family, however as their loved ones, we should avoid emotional over involvement, ridicule their beliefs or be intimidating.


If you wish to find out more on how to deal with delusions, please click here.