This document summarizes delusions, which are fixed false beliefs that are firmly held despite evidence to the contrary. It defines delusions and distinguishes them from overvalued ideas. It describes different types of delusions such as persecutory, grandiose, somatic, and mixed delusions. It also discusses primary delusions that occur suddenly versus secondary delusions caused by other conditions. Various disorders and medical conditions that can cause delusions are listed.

1. Delusion
Dr Rakesh Kumar Mehta
Department of Psychiatry
Nepalgunj Medical College

2. Introduction
• Delusion is a disorder of content of thought.
• Delusion can be defined as Fixed belief which is based
on inadequate background and is not susceptible to
reasonable argument or evidence to contrary and is
not shared by regional, cultural or educational
background.
• For example, a person with the delusion that
persecutors are in the next room will not alter his
belief when shown that the room is empty;

3. • A person with a delusion will hold firmly to the belief regardless of
evidence to the contrary.
• Delusions can be difficult to distinguish from overvalued ideas, which
are unreasonable ideas that a person holds, but the affected person
has at least some level of doubt as to its truthfulness.
• A person with a delusion is absolutely convinced that the delusion is
real.
• Delusions are a symptom of either a medical, neurological, or mental
disorder.

4. Delusion can be divided into bizarre and non-
bizarre.
• Non bizarre Delusions refer to thought content that is not true but is
not out of the realm of possibility.
• Eg. Person may have delusion that his neighbors are planning to kill him.
Although it may not be real but is completely possible.
• Bizarre Delusions refers to thought content that is not true and is not
possible too.
• Eg. Person may have delusion that all his internal organs has been taken out
by some external agencies. It is impossible.
• Aliens from another planet are coming to destroy the earth.

5. Causes
• CNS lesions, vitamin B12 deficiency, hepatic encephalopathy,
diabetes, and hypothyroidism.
• Disorders affecting the limbic system and basal ganglia
• Huntington's disease and in individuals with idiopathic basal ganglia
calcifications
• Epilepsy
• Bipolar disorder, Major depressive disorder with psychotic features,
Delirium, and Dementia.

6. Depending on the origin , delusion can be
classified into
1. Primary Delusion
2. Secondary Delusion

7. Primary Delusion
• These are the delusions that occurs suddenly without any other
mental/Psychopathological events.
• The core of primary delusion is that it is ultimately un-
understandable.
• For example, a patient may suddenly develop the unshakable
conviction that he is changing sex, without ever having thought of this
before and without any reason to do so at the time
• Primary delusions are rare, and when they occur they strongly
suggest schizophrenia
• Delusional perception

8. Secondary Delusion
• These are the delusions that occurs secondary to other
psychopathological conditions, previous abnormal ideas or
experience.
• Secondary delusions are understandable when a detailed psychiatric
history and examination is available
• For eg,
• Hallucination : A person may hear voices and believes that he is being
followed.
• Mood: A Depressed person may be feel of worthlessness and consequently
believes that others feels same about him.
• Delusion of Grandiose in Mania.

9. Types of Delusion
• Persecutory (paranoid)
• Reference
• Grandiose and expansive
• Guilt and worthlessness
• Nihilistic
• Somatic
• Erotomanic
• Control
• The possession of thoughts

10. Persecutory (paranoid) Delusion
• Persecutory delusions are ideas that people or organizations are
trying to inflict harm on the patient, damage his reputation, or make
him insane.
• Persecutory delusions are common in schizophrenia, and occur also in
organic states and severe depressive disorder
• The persecutory beliefs are often associated with irritability, and
anger, and the individual who acts out his or her anger may at times
be assaultive or even homicidal.

11. Jealous Type
• In delusions of infidelity a person has a delusion that a spouse or
partner has been unfaithful.
• Delusions of jealousy are more common among men
• Othello syndrome has been used to describe morbid jealousy
• Jealousy is a powerful emotion; when it occurs in delusional disorder
it can be potentially dangerous and has been associated with
violence, notably both suicide and homicide
• Can occur in schizophrenia (in which female patients more commonly
display this feature), epilepsy, mood disorders, drug abuse, and
alcoholism

12. Erotomanic Type
• Also called as de Clerambault syndrome or psychose passionelle.
• The patient has the delusional conviction that another person, usually
of higher status, is in love with him or her
• more frequent among women
• Patients with erotomania frequently show certain characteristics:
They are generally unattractive women in low-level jobs who lead
withdrawn, lonely lives; they are single and have few sexual contacts.

13. Grandiose Type
• Grandiose and expansive delusions are beliefs of exaggerated self-
importance.
• Patients may think them- selves wealthy, endowed with unusual
abilities, or in other ways special.
• Such ideas occur mainly in mania and sometimes in schizophrenia.

14. Somatic Type
• Delusional disorder with somatic delusions has been called
monosymptomatic hypochondriacal psychosis
• The three main types are
(1) delusions of infestation (including parasitosis);
(2) delusions of dysmorphophobia, such as of misshapenness,
personal ugliness, or exaggerated size of body parts
(3) delusions of foul body odors or halitosis.
• Hypochondriacal delusions occur in depressive disorders and
schizophrenia.

15. Mixed Type
• The category mixed type applies to patients with two or more
delusional themes.
• This diagnosis should be reserved for cases in which no single
delusional type predominates.

16. Unspecified Type
• The category unspecified type is reserved for cases in which the
predominant delusion cannot be subtyped within the pre vious categories
• Capgras syndrome
• belief that a familiar person has been replaced by an impostor.
• Fregoli Syndrome
• belief that different people are in fact a single person who changes appearance or is
in disguise
• Cotard syndrome
• sometimes referred to as nihilistic delusional disorder
• beliefs that the patient’s career is finished, that he is about to die or has no money,
or that the world is doomed.

17. • Delusions of control are beliefs that personal actions, impulses, or
thoughts are controlled by an outside agency.
• Delusions concerning the possession of thoughts.
found most often in schizophrenia and include:
• (i) delusion of thought insertion—some of the person’s thoughts have been
implanted by an outside agency;
• (ii) delusion of thought withdrawal—some of their thoughts have been
taken away;
• (iii) delusion of thought broadcasting—some of their thoughts are known to
other people through telepathy, radio, or some other unusual way.

18. • Delusions of reference
• Objects, events, or the actions of other people have a special significance for
the patient.
• For example, a remark heard on television is believed to be directed
specifically to the patient, or a gesture by a stranger is believed to
convey something about the patient.
• Delusions of this kind are associated with schizophrenia.

19. • Delusional perception
• This is the misinterpretation of the significance of
something perceived normally.
•For example, a patient may suddenly be convinced
that the particular arrangement of objects on his
desk indicates that his life is threatened.

20. • Shared delusions
• A person who lives with or is otherwise in a close relationship with a deluded
patient comes to share the delusional beliefs.
• This person is then said to have shared delusions or folie à deux.
• Lycanthropy
• The false belief that the patient is an animal, often a wolf or "were wolf"
• Heautoscopy
• The false belief that one has a double
• reduplicative hallucination of "seeing one's own body at a distance"

21. • Thank You