diagnosis and classification of schizophrenia Flashcards
who is most commonly diagnosed with schizophrenia?
- men
- city-dwellers
- lower socio-economic class
what is the approximate lifetime risk in the general population?
- <1% (NHS)
- this holds true for most geographical areas although rates do vary
torrey (2002) - rates of schizophrenia
- abnormally high in southern ireland and croatia
- significantly lower rates in italy and spain
what are some risk factors for schizophrenia?
- low socio-economic class
- ethnic minority
- urban residence
what are the consequences of symptoms of schizophrenia?
- can interfere severely with everyday tasks
- many people end up homeless or hospitalised
how is a diagnosis made according to the medical approach?
- to diagnose a specific disorder, we need to distinguish one disorder from another
- identify clusters of symptoms that occur together and classify this as a disorder
- diagnosis is possible by identifying symptoms and deciding what disorder a person has
what are the two major systems for the classification of mental disorders?
- world health organisation’s ‘international classification of disease’ (ICD-10)
- american psychiatric association’s ‘diagnostic and statistical manual (DSM-5)
what criteria is necessary for a diagnosis according to the ICD-10?
- symptoms present most of the time for at least 1 month
- disorder not from substance use or organic brain disease
at least one of the following:
- echoing / insertion / withdrawal / broadcasting of thought
- delusional perceptions
- hallucinatory voices
- impossible delusions
OR
at least two of the following:
- persistent hallucinations in any modality
- incoherence or irrelevant speech
- catatonic behaviour
- negative symptoms
what criteria is necessary for a diagnosis according to the DSM-5?
at least two of the following: (at least one must be 1,2 or 3)
1. delusions
2. hallucinations
3. disorganised speech
4. grossly disorganised or catatonic behaviour
5. negative symptoms
- symptoms must be present for at least 1 month
- level of functioning must be significantly and long term lowered compared to the previously achieved level
- continuous signs of disturbance persists for at least 6 months, must include symptoms 1, 2 or 3 for at least 1 month
- schizoaffective disorder and depressive or bipolar disorder with psychotic symptoms are ruled out
- disturbance is not caused by substance use or medical conditions
what did previous editions of ICD and DSM recgonise that they no longer do?
- subtypes of schizophrenia
- eg. paranoid schizophrenia mainly involved powerful hallucinations and delusions
why have DSM-5 and ICD-10 both dropped subtypes?
- tended to be inconsistent
- eg. someone with a diagnosis of paranoid schizophrenia would not necessarily show the same symptoms a few years later
describe what positive symptoms are
atypical symptoms experienced in addition to normal experiences which appear to reflect an excess or distortion of normal functions
what are some examples of positive symptoms? (5)
- hallucinations
- disordered thinking
- speech disorganisation
- delusions
- experiences of control
positive symptoms: hallucinations
- unusual sensory (auditory / visual / olfactory / tactile) experiences
- can be related to events in the environment or have no relation
positive symptoms: disordered thinking
feeling that thoughts have been inserted or withdrawn from the mind
positive symptoms: speech disorganisation (DSM-5)
- speech becomes incoherent
- speaker changes topic mid-sentence
- loosely associated speech is associated with thought disorder
positive symptoms: delusions
- aka paranoia
- irrational beliefs which seem real to the person with schizophrenia but are not real
- make a person behave in ways that make sense to them but seem bizarre to others
what are some common delusions? (4)
- being an important historical, political or religious figure
- being persecuted eg. by government or aliens
- having superpowers
- under external control eg. alien force
describe what negative symptoms are
atypical experiences that represent the loss of a usual experience and normal functions
what are some examples of negative symptoms?
- affective flattening
- speech poverty (alogia)
- avolition (apathy)
negative symptoms: affective flattening
reduction in range and intensity of emotional expression:
- facial expression
- voice tone
- eye contact
- body language
negative symptoms: speech poverty (alogia)
- lessened fluency, productivity, and quality of speech
- sometimes accompanied by a delay in the person’s verbal responses during conversation
negative symptoms: avolition (apathy)
- difficult to begin or keep up with goal-directed activity
- reduced motivation to carry out a range of activities
three signs of avolition (andreasen 1982)
- poor hygiene and grooming
- lack of persistence in work or education
- lack of energy
evaluation: good reliability
- a psychiatric diagnosis is said to be reliable when different diagnosing clinicians reach the same diagnosis for the same individual (inter-rater reliability) and when the same clinician reaches the same diagnosis for the same individual on two occasions (test-retest reliability)
- prior to DSM-5, reliability for diagnosis was low but this has now improved
evidence for good reliability (osório et al. 2019)
- reported excellent reliability for the diagnosis of schizophrenia in 180 individuals using DSM-5
- pairs of interviewers achieved inter-rater reliability of +0.97 and test-retest reliability of +0.92
evaluation: low criterion validity (cheniaux et al. 2009)
- had 2 psychiatrists independently asess the same 100 clients using ICD-10 and DSM-IV criteria
- 68 were diagnosed under the ICD system, 39 under DSM
- schizophrenia is over- or underdiagnosed
evaluation: good criterion validity
- osório et al. reported excellent agreement between clinicians when they used measures both derived from the DSM system
- criterion validity may be good as long as it takes place within a single diagnostic system
evaluation: co-morbidity
- if conditions occur together often, this calls into question the validity of their diagnosis and classification as they might actually be a single condition
- schizophrenia may not exist as a distinct condition
- at least some people diagnosed with schizophrenia may have unusual cases of condition like depression
- clinicians make dual diagnosis-appropriate treatment for both disorders
- DSM is a multaxial classification system which encourages multiple diagnoses
evidence for co-morbidity (buckley et al.)
- 50% co-morbidity with depression
- 47% co-morbidity for substance abuse
- 23% co-morbidity for OCD
evidence for co-morbidity (swets et al. 2014)
- meta-analysis
- 12% of schizophrenia patients also fulfilled the diagnostic criteria for OCD
- approx. 12% displayed significant OCD symptoms
evaluation: gender bias in diagnosis (fischer and buchanan 2017)
- since the 1980s, men have been diagnosed more commonly than women in a 1.4:1 ratio
- beore 1980s, there was no difference
- this could be due to men having a genetic vulnerability
evaluation: gender bias in diagnosis (cotton et al. 2019)
- women are underdiagnosed because they have closer relationships so get support
- women with schizophrenia are often better functioning than men
- women may not be receiving treatment and services that benefit them
evaluation: cultural bias
- some symptoms of schizophrenia, especially hearing voices, have different meanings in different cultures
- eg. in haiti, some people believe voices are communications from ancestors
evidence for cultural bias (luhrmann 2015)
- interviewed 60 adults with a diagnosis of schizophrenia
- asked about the voices they heard
- 20 from ghana, 20 from india, 20 from US
- ps from ghana & india reported positive experiences with their voices (playful, offered advice)
- US ps reported only negative experiences (hateful, violent)
evidence for cultural bias (pinto and jones 2008)
- british people of african-caribbean descent are up to 9x more likely to be diagnosed with schizophrenia than white british people
- rates in africa and west indies are not particularly high, so there is not a genetic vulnerability
- likely due to culture bias in diagnosis of clients by psychiatrists from a different cultural background
evidence for cultural bias (escobar 2012)
- cultural bias leads to an overinterpretation of symptoms in black british people
- british african-caribbean people may be discrimated against by a culturally-biased diagnostic system
evaluation: sympton overlap
- overlap between schizophrenia and bipolar disorder positive symptoms (eg. delusions) and negative symptoms (eg. avolition)
- schizophrenia and BPD may not be two different conditions but variations of a single condition
- differentiating between them is difficult
- misdiagnosis risk increases if boundaries are unclear
- holistic approach is effective as it allows for individualised approach
