Delusion

Clinic

• It is an entity, means having a false fixed belief that is not changed in by nay evidence.
• Along with Altered pattern of thought, they are Thought entities. Delusion is disturbances of thought content and Altered pattern is disturbances of pattern of thinking.
• As a pathology, it is distinct from a belief based on false or incomplete information, confabulation, dogma, illusion, hallucination, or some other misleading effects of perception, as individuals with those beliefs are able to change or readjust their beliefs upon reviewing the evidence. However:

"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."

• Here I claim that Delusion is a sign of Psychosis.
• Note that ... it means that there maybe some patients who have delusions but not have psychosis. Since for labeling psychosis, the patient must have Delusion and

Causes

Dynamic	Static
Schizophrenia Paraphrenia Manic episodes of bipolar disorder Psychotic depression

Types

Delusions are categorized into four different groups:

• Bizarre delusion: 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 named by the DSM-5 is a belief that someone replaced all of one's internal organs with someone else's without leaving a scar, depending on the organ in question.
• Non-bizarre delusion: A delusion that, though false, is at least technically possible, e.g., the affected person mistakenly believes that they are under constant police surveillance.
• Mood-congruent delusion: Any delusion with content consistent with either a depressive or manic state, e.g., a depressed person believes that news anchors on television highly disapprove of them, or a person in a manic state might believe they are a powerful deity.
• Mood-neutral delusion: A delusion that does not relate to the patient's emotional state; for example, a belief that an extra limb is growing out of the back of one's head is neutral to either depression or mania.

Themes

In addition to these categories, delusions often manifest according to a consistent theme. Although delusions can have any theme, certain themes are more common. Some of the more common delusion themes are:

Types

Grandiose delusions	It is a subtype of delusional disorder but could possibly feature as a symptom of schizophrenia and manic episodes of bipolar disorder. It is characterized by fantastical beliefs that one is famous, omnipotent or otherwise very powerful. The delusions are generally fantastic, often with a supernatural, science-fictional, or religious bent. In colloquial usage, one who overestimates one's own abilities, talents, stature or situation is sometimes said to have "delusions of grandeur". This is generally due to excessive pride, rather than any actual delusions. Grandiose delusions or delusions of grandeur can also be associated with megalomania.
Persecutory delusions	The most common type of delusions and involve the theme of being followed, harassed, cheated, poisoned or drugged, conspired against, spied on, attacked, or otherwise obstructed in the pursuit of goals. They wrongly believes that they are being persecuted. Specifically, they have been defined as containing two central elements
Delusion of poverty	Person strongly believes they are financially incapacitated. Although this type of delusion is less common now, it was particularly widespread in the days preceding state support.
Somatic delusion:	Delusion whose content pertains to bodily functioning, bodily sensations or physical appearance. Usually the false belief is that the body is somehow diseased, abnormal or changed. A specific example of this delusion is delusional parasitosis: Delusion in which one feels infested with insects, bacteria, mites, spiders, lice, fleas, worms, or other organisms.
	Religious delusion: Belief that the affected person is a god or chosen to act as a god.
	Erotomania: False belief that another person is in love with them.
	Delusion of reference: False belief that insignificant remarks, events, or objects in one's environment have personal meaning or significance. "Usually the meaning assigned to these events is negative, but the 'messages' can also have a grandiose quality."
	Persecutory delusions: False belief that one is being persecuted.
Delusion of thought insertion:	Belief that another thinks through the mind of the person.
Thought broadcasting:	False belief that other people can know one's thoughts.
Delusion of guilt or sin (or delusion of self-accusation):	Ungrounded feeling of remorse or guilt of delusional intensity.
Delusional jealousy	False belief that a spouse or lover is having an affair, with no proof to back up the claim.
Cotard delusion	False belief that one does not exist or that one has died. Some cases also include the belief that one is immortal or that one has lost their internal organs, blood, or other body parts.
Delusion of control	False belief that another person, group of people, or external force controls one's general thoughts, feelings, impulses, or behaviors.

Pathophysiology

The two-factor model of delusions posits that dysfunction in both belief formation systems and belief evaluation systems are necessary for delusions. Dysfunction in evaluations systems localized to the right lateral prefrontal cortex, regardless of delusion content, is supported by neuroimaging studies and is congruent with its role in conflict monitoring in healthy persons. Abnormal activation and reduced volume is seen in people with delusions, as well as in disorders associated with delusions such as frontotemporal dementia, psychosis and Lewy body dementia. Furthermore, lesions to this region are associated with "jumping to conclusions", damage to this region is associated with post-stroke delusions, and hypometabolism this region associated with caudate strokes presenting with delusions.^{[citation needed]}

The aberrant salience model suggests that delusions are a result of people assigning excessive importance to irrelevant stimuli. In support of this hypothesis, regions normally associated with the salience network demonstrate reduced grey matter in people with delusions, and the neurotransmitter dopamine, which is widely implicated in salience processing, is also widely implicated in psychotic disorders.^{[citation needed]}

Specific regions have been associated with specific types of delusions. The volume of the hippocampus and parahippocampus is related to paranoid delusions in Alzheimer's disease, and has been reported to be abnormal post mortem in one person with delusions. Capgras delusions have been associated with occipito-temporal damage and may be related to failure to elicit normal emotions or memories in response to faces.