What are Delusions?

A delusion is a belief with strong conviction despite evidence to the contrary. Delusions are false beliefs or misinterpretations of events & their significance.  This is pathological and is different from a belief based on false or incomplete information, confabulation, some dogma or because of perception. Delusions are a symptom of medical, neurological, or mental disorder and are of diagnostic importance.

Delusions may be present in any of the following mental disorders:

  • Psychotic disorders including schizophrenia, schizoaffective disorder, delusional disorder, schizophreniform disorder, shared psychotic disorder, brief psychotic disorder, and substance-induced psychotic disorder
  • Bipolar disorder
  • Major Depressive Disorder with psychotic features
  • Delirium
  • Dementia 

Criteria of delusion are:

  • Certainty that means it is held with absolute conviction
  • Incorrigibility that means it is not changeable by compelling counterargument or proof to the contrary
  • Impossibility or falsity of content that means it is implausible, bizarre or patently untrue 

Delusions are categorized into four different groups:

  • Bizarre delusion – Delusions if they are clearly impossible and not understandable to same culture people and does not derive from or relate to ordinary life experiences.
  • Non bizarre delusion – A delusion though false is at least possible e.g., the affected person mistakenly believes that he is followed by someone.
  • Mood congruent delusion – Any delusion with its content correspond to or is consistent with either a depressive or manic state e.g., a depressed person believes that he or she is looked down upon by office colleagues or they highly disapprove of him, or a person in a manic state might believe she is a powerful and must control others.
  • Mood neutral delusion – A delusion that has no relation to the emotional state for example a belief that there is something moving in his head is not related to either depression or mania. 


Delusions are also explained according to theme they display. Some of the more common delusion themes are:

  • Grandiose delusions: In Grandiose delusions person is convinced that he or she has special powers, talents, or abilities or they are a famous person or character. This may be of super natural character, science fiction or religious characteristic. This super natural power could be to save or destroy others.
  • Persecutory delusions: In Persecutory delusions person believes that he or she is being conspired against, followed, harassed, cheated, poisoned, drugged, spied on, sabotaged, ridiculed, attacked or obstructed in doing work or in pursuit of his or her goals. The individual believes that some harm is being done or going to occur. They also believe that there are people who have clear cut intention to do such harm and are targeting him or her.
  • Delusion of control: A person believes that his thoughts, feelings or behavior are being controlled by someone else or external force.
  • Cotard delusion: This is a false belief that he or she is dead and deny own existence.
  • Delusional jealousy: A person believes that a spouse or lover is having an affair. There is no proof to back up their claim.
  • Delusion of guilt or sin or self-accusation: Person believes he or she has done something wrong and has an ungrounded feeling of remorse or guilt of huge intensity.
  • Delusion of mind being read: Person believes that his or her mind is being read by others directly or through some gadget.
  • Delusion of thought insertion: Person believes that someone is inserting thoughts inside his or her mind.
  • Delusion of reference: The person believes that insignificant remarks, events, or objects in his or her environment are related to him or her and have personal meaning or significance.
  • Erotomania: Person believes that another person is in love with him or her. Any amount of denial will not convince.
  • Grandiose religious delusion: Person believes that he or she is God sent or chosen one to act on behalf of or as God.
  • Somatic delusion: These are false beliefs related to own body appearance, sensation or function. They believe body is abnormal or changed. This is different from hypochondriacal anxiety in which person has abnormal worry about being sick.
  • Delusion of poverty: Person has belief that he or she is very poor or bankrupt.