Delusions vs Hallucinations: Halucinations are false perceptions in a sensory modality with no basis in reality. e.g. the patient hears, sees or feels (rarely touches or tastes) something that has no basis in reality. A delusion has no sensory component but the two may be hard to separate historically as there may be a delusional belief that e.g. the patient has seen someone following him.

---

Delusions are common enough that psychiatrists have divided them up into multiple discrete types and it is usually possible to see easily which one your patient has.

Control: see Passivity

Eroticism or Love: the patient believes that another person, usually of higher status, is in love her. Attempts to rebuff by the object of affection may paradoxically be taken as 'secret signs' confirming the love felt by the target of the obsession.

Guilt: the patient is disturbed by guilt for a minor or imaginary event. Perhaps he imagines that police wish to arrest him for a childhood shoplifting or that 'sinful' behaviour will bring shame to his family. This delusion is most common in severe depression.

Hypochondriasis: the patient is convinced they are ill - unlike overvalued ideas or obsessions related to illness, the patient is unlikely to be convinced by negative tests.

Jealousy: Delusional jealousy is recorded in several good textbooks but in my opinion delusions of unfaithfulness is a better name as the jealousy is a real emotion caused by delusions that the spouse or lover is cheating on them. This delusion may have dangerous consequences for the spouse as violence is not uncommon.

Grandiosity: the patient believes that he is 'special' in some way. He may be Royal, have special powers, have a task from God or something similar. These are most commonly associated with bipolar disorder, hypomania, and schizophrenia.

Misidentification: e.g. the belief that a familiar person has been replaced by an identical impostor (Capgras syndrome) or that a familiar person is disguised as someone else (Fregoli syndrome). These are rare and frequently are associated with other psychiatric conditions (eg, schizophrenia) or organic illnesses (eg, dementia, epilepsy)

Nihilistic: In this type of delusion the patient believes something is vanishing. He may have lost all his money, her organs may be disappearing or, at the extreme, the world may be ending.

Passivity: the patient believes that his physical actions are under the control of another - they can make him do things that he has no control over - his body literally moves at the will of another. This is different to doing something in response to an auditory hallucination or compulsion. This is a rare phenomenon - usually encountered in schizophrenia. It has worrying forensic implications as people may perform dangerous acts that they feel they have no control over.

Persecution: the patient believes that someone is 'after him' in some way and either now or in the future wishes to harm him. This type of delusion could be of people listening to his conversations, bugging his house, following him around, or even that he has been attacked. Sadly, it is sometimes difficult to separate delusion from real persecution. People who act 'oddly' via mental illness or learning difficulties are often targetted for abuse of varying sorts and are sometimes very vulnerable - it is important to bear this in mind.

Reference: the patient believes that certain things in the environment have a special message for him. Examples include that people on television are talking about him or that newspapers contain secret messages for him. The gestures of stragers may have 'hidden messages' contained that only he can perceive.

Thought insertion: the patient believes that thoughts are being placed within her head. This is not via the words of others but by some form of other delusional process such as 'radio waves' or 'telepathy'.

Thought withdrawal: the patient believes that thoughts are being 'taken' from her head - this often occurs with thought blocking. In this phenomenon there is a break in the patients chain of thoughts and he may attribute this to the thought being 'removed' by another person.

Thought broadcast: the patient believes that his thoughts are being heard by others.

Somatic: these are delusions centred around bodily functions and sensations. The most common are the belief that one is infested with insects or parasites, emitting a foul odor, that parts of the body are not functioning, or that their body or parts of the body are misshapen or duplicated.


NB: The male and female pronouns are used interchangeably

---

Delusional Perception: this is a little different conceptually to the delusions above. To give an example:

• Mr smith sees a red car pass him just as he leaves his house - he knows that this means he is being watched by aliens.

Note that the red care is a real perception - it is the idea that comes after that is the delusion.

A delusional perception can be thought of as a delusional belief arising from a real perception.

Bipolar disorder: additional symptoms in the manic phase include wild spending, increased libido, gambling, and pressure of speech. In the depressive phase symptoms are as depression.

Dementia: additional symptoms include memory loss; difficulty performing familiar tasks; problems with language; disorientation to time and place; poor or decreased judgement; problems with keeping track of things; misplacing things; changes in mood, behavior or personality; Loss of initiative.

Depression: additional symptoms include poverty of speech, sleep dysfunction, altered appetite, loss of libido, anhedonia and a subjective low mood. Ask about suicidal ideation.

Induced delusional disorder (DSM-IV: shared psychotic disorder): The old, and probably more familiar, name for this disorder is Folie a Deux - it is characterised by two or more sharing the same delusion.

Primary delusional disorder: there will be no symptoms except the delusion(s).

Schizophrenia: this is a disease entity encompassing many many presentations. Always ask about suicidal ideation. Schneiders first rank symptoms comprise four characteristic hallucinations and 5 characteristic delusions. Any one of these is strongly suggestive of schizophrenia:

Four Hallucinations

• Auditory hallucinations in the third person (talking about the patient)
• Auditory hallucinations of a running commentary on one's own actions.
• Auditory hallucinations of hearing one's own thoughts spoken aloud
• Somatic hallucinations

Five Delusions

• Relating to thought: thought insertion, withdrawal, broadcast
• Delusional perception.
• Passivity phenomena (feeling of actions being controlled)

Substance related: intoxication, withdrawal or psychosis from the use of. Obviously a history of drug or alcohol use is vital in forming this diagnosis. Ask about suicidal ideation.

---

Click here if you wish to reproduce any information from this page.

---