Epidemiology
- Incidence: 16.00 cases per 100,000 person-years
- Peak incidence: 30-40 years
- Sex ratio: more common in males 1.4:1
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Aetiology
The strongest risk factor for developing a psychotic disorder (including schizophrenia) is family history. Having a parent with schizophrenia leads to a relative risk (RR) of 7.5.
Risk of developing schizophrenia
Other selected risk factors for psychotic disorders include:
Risk of developing schizophrenia
- monozygotic twin has schizophrenia = 50%
- parent has schizophrenia = 10-15%
- sibling has schizophrenia = 10%
- no relatives with schizophrenia = 1%
Other selected risk factors for psychotic disorders include:
- Black Caribbean ethnicity - RR 5.4
- Migration - RR 2.9
- Urban environment- RR 2.4
- Cannabis use - RR 1.4
Clinical features
Schneider's first rank symptoms may be divided into auditory hallucinations, thought disorders, passivity phenomena and delusional perceptions:
Auditory hallucinations of a specific type:
Thought disorder*:
Passivity phenomena:
Delusional perceptions
Other features of schizophrenia include
*occasionally referred to as thought alienation
Auditory hallucinations of a specific type:
- two or more voices discussing the patient in the third person
- thought echo
- voices commenting on the patient's behaviour
Thought disorder*:
- thought insertion
- thought withdrawal
- thought broadcasting
Passivity phenomena:
- bodily sensations being controlled by external influence
- actions/impulses/feelings - experiences which are imposed on the individual or influenced by others
Delusional perceptions
- a two stage process) where first a normal object is perceived then secondly there is a sudden intense delusional insight into the objects meaning for the patient e.g. 'The traffic light is green therefore I am the King'.
Other features of schizophrenia include
- impaired insight
- incongruity/blunting of affect (inappropriate emotion for circumstances)
- decreased speech
- neologisms: made-up words
- catatonia
- negative symptoms: incongruity/blunting of affect, anhedonia (inability to derive pleasure), alogia (poverty of speech), avolition (poor motivation)
*occasionally referred to as thought alienation
Management
NICE published guidelines on the management of schizophrenia in 2009.
Key points:
Key points:
- oral atypical antipsychotics are first-line
- cognitive behavioural therapy should be offered to all patients
- close attention should be paid to cardiovascular risk-factor modification due to the high rates of cardiovascular disease in schizophrenic patients (linked to antipsychotic medication and high smoking rates)
Prognosis
Factors associated with poor prognosis
- strong family history
- gradual onset
- low IQ
- premorbid history of social withdrawal
- lack of obvious precipitant