Delusions are fixed beliefs that are not amenable to change in light of conflicting evidence. Their content may include a variety of themes:

  • persecutory
  • referential
  • somatic
  • religious
  • grandiose

Persecutory delusions: the belief that one is going to be harmed, harassed, and so forth by an individual, organization, or other groups are most common.

Referential delusions: belief that certain gestures, comments, environmental cues, and so forth are directed at oneself are also common.

Grandiose delusions: when an individual believes that he or she has exceptional abilities, wealth, or fame and erotomanic delusions: when an individual believes falsely that another person is in love with him or her are also seen.

Nihilistic delusions: involve the conviction that a major catastrophe will occur, and somatic delusions focus on preoccupations regarding health and organ function.

Delusions are deemed bizarre if they are clearly implausible and not understandable to same-culture peers and do not derive from ordinary life experiences.

An example of a bizarre delusion is the belief that an outside force has removed his or her internal organs and replaced them with someone else’s organs without leaving any wounds or scars.

An example of a nonbizarre delusion is the belief that one is under surveillance by the police, despite a lack of convincing evidence.

Delusions that express a loss of control over mind or body are generally considered to be bizarre; these include the belief that one’s thoughts have been “removed” by some outside force (thought withdrawal), that alien thoughts have been put into one’s mind (thought insertion), or that one’s body or actions are being acted on or manipulated by some outside force (delusions of control). The distinction between a delusion and a strongly held idea is sometimes difficult to make and depends in part on the degree of conviction with which the belief is held despite clear or reasonable contradictory evidence regarding its veracity.