psychiatry: psychoses Flashcards
delusions definition
A delusion is a false belief which is firmly sustained and based on incorrect inference about reality. This belief is held despite evidence to the contrary and is not accounted for by the person’s culture or religion.
criteria for delusions
- Certainty - the patient believes the delusion absolutely.
- Incorrigibility - the belief can not be shaken.
- Impossibility - the delusion is without doubt untrue.
hallucination definition
a sensory perception which is experienced despite there being no external stimulus. Hallucinations can occur with any sense and thus be visual, auditory, olfactory, gustatory or tactile.
pseudohallucination definition
the patient is aware of a stimulus which they realise is in their mind, eg hearing a voice. This differentiates them from hallucinations, which can be localised in a three-dimensional space outside the body
psychosis definition
Misperception of thought and perceptions that arise from the patient’s own mind as reality, includes delusions and hallucinations. It is a symptom, not diagnosis.
Psychotic disorders include:
- Schizophrenia
- Schizoaffective disorder
- Delusional disorder
- Brief psychotic episodes
- Psychotic depression
- Bipolar affective disorder
- Drug-induced psychoses
schizophrenia epidemiology
incidence of 15.2 per 100,000 person-years. A systematic review reported a prevalence of 7.2/1,000 persons. Age of onset is usually <35 y for females
aetiology schizophrenia
Multiple factors: genetic, environmental and social. Short-lived illnesses similar to paranoid schizophrenia are associated with cocaine, amfetamines and cannabis. Cannabis especially in both established schizophrenia and in enhancing future risk of schizophrenia in those who have not yet developed psychotic symptoms.
differentials for schizophrenia
Differentials Organic disorders • Drug-induced psychosis - amphetamine, LSD, cannabis • Temporal lobe epilepsy • Encephalitis • Alcoholic hallucinosis • Dementia • Delirium due to infection, metabolic or toxic disturbance, neurological disease, endocrine cause, etc • Cerebral syphilis (still rare, although worldwide incidence of syphilis has been increasing) Psychiatric conditions • Mania • Psychotic depression
first rank or positive symptoms in schizophrenia
(ATPD – Aim To Pass Definitely) Auditory hallucinations, specifically: 1. Third person (two or more voices heard discussing the patient – 3rd person) 2. Running commentary 3. Thought echo
Thought disorder (passivity of thought – under external control)
- Thought withdrawal
- Thought insertion
- Thought broadcasting
Passivity experiences (delusions of control)
- Actions/feelings/impulses under external control
- Bodily sensations due to external influence
Delusional perception (two stage process)
- Normal perception of commonplace object/sight leads to…
- Sudden, intense, self-referential delusion (eg finding a coin on the ground leads to belief of messianic role)
second rank symptoms in schizophrenia
symptoms are common in schizophrenia but also occur in other disorders: catatonic behaviour, second-person auditory hallucinations.
current diagnosis of schizophrenia
At least 1 First rank symptom or persistent delusions + present for at least a month (ICD-10) or 6 months (DSM-IV-TR) + no drug intoxication, withdrawal, overd brain disease or prominent affective symptoms.
types of delusions in schizophrenia
- Persecutory (someone is out to harm the patient)
- Delusions of reference (patient is mentioned on TV or knows that people are taling about him/her)
- Formal thought disorder may occur:
a. Loosening of associations
b. Neologisms
c. Concrete thinking (inability to deal with abstract ideas)
d. Word salad
schizophrenia symptoms can be classified into:
- Positive (hallucinations, delusions)
- Negative (poverty of speech, flat affect, poor motivation, social withdrawal, lack of concern for social convention
- Cognitive (poor attention and memory)
types of schizophrenia
paranoid catatonic hebephrenic residual (chronic) undifferentiated (simple)
