introduction to schizophrenia

what is schizophrenia

a group of psychotic disorders characterised by a loss of contact with reality

what is the prevalence rate of Sz

1% of the population

onset of symptoms 15-45 yrs- higher likelihood and earlier onset in males

how is Sz identified

DSM 5 (USA) is most commonly used as well as the ICD 11 (Europe)

2 symptoms must be present for at least a month, with at least one being positive

what are the types of symptoms of Sz

positive- in addition to normal experiences

negative- a loss of normal experiences and abilities

examples of positive symptoms

hallucinations- additional sensory experiences eg distortions in objects/ hearing critical voices

delusions- irrational beliefs about themself / the world eg feelings of persecution or grandeur

disorganised speech- incoherent speech/ topic changes mid sentence

examples of negative symptoms

avolition- a lack of purposeful willed behaviour, no energy, sociability, affection, or attempt at personal hygiene

speech poverty/alogia- brief verbal communication style. loss of quality and quantity of verbal responses (can be pos if disorganised speech)

affective flattening- reduction in emotional expressiveness eg monotone voice and decreased body language

Anhedonia- reduced ability to experience pleasure/ interest in previously enjoyed activities

what is reliability

the consistency of results

what is validity

the truth of results

being real and distinct from other disorders

what is test retest reliability

the agreement over time by the same doctor

what is interobserver reliability

agreement between 2 observers/ doctors

AO3 for reliability

an issue for diagnosis of schizophrenia is a lack of interobserver reliability

The lack of reliability may be may be caused by classification systems lending themselves to misinterpretation

Reliability of Sz diagnosis is low between countries and classification systems

An issue with diagnosis of Sz is low test retest reliability

An issue for diagnosis of Sz is a lack of inter observer reliability

Beck reviewed 153 patients diagnosed by multiple doctors and found only 54% concordance between the doctors assessments. Similarly, Whaley (2001) found inter rater reliability correlations as low as 0.11.
This indicated that there may be misdiagnosis of Sz leading to failure to access correct treatment

The lack of reliability may be caused by classification systems lending themselves to misinterpretation

for example, using the DSM, only 1 of the characteristics are required ‘if delusions are bizzare’ which can create issues. Mojtabi and Nicholson found that 50 senior US psychiatrists had only 0.4 concordance when asked to differentiate between bizzare and non bizzare delusions.
This suggests that the central diagnostic requirement lacks clarity and reliability and so the DSM cannot be a reliable method

Reliability of Sz diagnosis is low between countries/ classification systems

Copeland (1971) gave 134 US and 194 British psychiatrists a description of a patient. 69% of US diagnosed schizophrenia but only 2% of British psychiatrists gave the same diagnosis.

Cooper suggested new york psychiatrists were 2x as likely to diagnose Sz than london psychiatrists, when shown the same video interviews. An implication is that the classification systems and psychiatric practices between countries are not comparable, leading to misdiagnosis and suggesting the systems may not be fit for purpose

an issue with diagnosis of SZ is the low test retest reliability

Evidence comes from Read who suggested test retest reliability of Sz diagnosis has only 37% concordance. This may be improving eg using cognitive screening tests such as RBANS which measure the degree of neuropsychological impairment and have improved reliability of diagnosis. This is evidenced by Wilks et al 2003 who administered 2 forms of the test to Sz patients and found high test retest reliability at 0.84

This shows more objective measures can improve reliability of diagnosis

what are the types of validity

predictive validity

descriptive validity

aetiological validity

what is predictive validity

if diagnosis leads to successful treatment

what is descriptive validity

patients should differ in symptoms from patients with other disorders

what is aetiological validity

all with the disorder should have the same cause

AO3 for validity

there are mixed views as to whether high levels of predictive validity exist in the classification/ diagnosis of Sz

There are mixed views surrounding potential descriptive validity of Sz

there is suggestion of low to no aetiological validity in the classification and diagnosis of Sz

there are mixed views as to whether high levels of predictive validity exist in the classification/ diagnosis of Sz

Birchwood and Jackson argue that there can never be high predictive validity due to variations in Sz. They found 20% recover and never have another episode while 10% are so affected they commit suicide. However, Mason tested predictive validity of 4 classification systems over 13 years and found newer systems showed more predictive validity

while there are limitations to the extent of predictive validity, it is suggested to be improving

There are mixed views surrounding the potential descriptive validity of Sz

jager suggested high descriptive validity with ICD 10 distinguishing 951 Sz cases from 51 delusional disorders and 354 Schizoaffective disorders. Their patients with Sz had more negative symptoms and lower overall functioning. However Allardyce claims there are too many variations between patients and so it is not possible to diagnose Sz as a separate disorder

Thus, there are questions of the validity and subsequent treatments for Sz patients

There is suggestion of low to no aetiological validity in the classification and diagnosis of Sz

Baillie surveyed 154 British psychologists and found some agreement to the influence of genetics, biochemical abnormalities and substance abuse, but overall widely differing views about the cause of Sz

Furthermore, Bentall claims the diagnosis of Sz says nothing about its cause, implying diagnosis is invalid

The lacking agreement of the cause or Sz limits the reliability of diagnosis

what is comorbidity

the extent that one or more disorders or diseases occur simultaneously with Sz

examples of common comorbidities with Sz

substance abuse

anxiety

depression

AO3 for co morbidity

Comorbidity makes diagnosis less valid and creates difficulties in treatment due to confusion over what disorder is being diagnosed

There are high levels of Comorbidity between Sz and other conditions

There is a suggestion that the high levels of comorbidity reveal more about Sz

Comorbidity makes diagnosis less valid and creates difficulties in treatment due to confusion over what disorder is being diagnosed

Comorbid substance abuse (found in 47% of Sz patients) makes diagnosis less valid and reduces functioning/ compliance with medication, and so males treatment more difficult

This shows how comorbidity makes not only diagnosis, but treatment of the disorder more difficult

There are high levels of comorbidity between Sz and other conditions

Buckley estimated comorbidity of 50% with depression, 47% with substance abuse, 15% with panic disorder, 29% with PTSD, and 23% with OCD. The high comorbidity levels may reduce the validity of diagnosis as well as making treatment more complex

There is a suggestion that the high levels of comorbidity reveal more about Sz

It may be argued that high levels of comorbidity are evidence of separate subtypes of the disorder. This creates an issue for descriptive validity, as having simultaneous disorders suggests Sz may not be a separate and distinct disorder

what is symptom overlap

the extent that symptoms of Sz can also be found in other disorders eg bipolar disorder also has hallucinations and delusions as symptoms

AO3 for symptom overlap

symptom overlap makes diagnosis difficult

There is genetic overlap between Sz and bipolar disease

symptom overlap makes diagnosis difficult

ellason and ross found that those with DID have more symptoms of Sz than those with Sz. This means it is difficult to separate and diagnose Sz from other disorders as they present similarly

This may lead to misdiagnosis and incorrect treatment, leading to suffering and high risk of suicide

There is genetic overlap between Sz and bipolar disorder

Ophoff assessed genetic material from 50,000 cases and found that of 7 gene locations associated with Sz 3 were also linked to bipolar disorder. This suggests the 2 disorders have a genetic overlap.
This provides scientific evidence for the overlap between Sz and bipolar

what is bias

implies a form of distorition that can affect how individuals or groups are perceived

what is emic

analyses culturally specific behaviour

what is etic

analyses universals of human behaviour

what is imposed etic

where a construct from one society is inappropriately applied to another

what is the impact of cultural bias on Sz

there is a tendency to overdiagnose members of other cultures as suffering from Sz

In britain those of Afro- Carribean descent are more likely to be diagnosed than white people and are more likely to be confined to hospitals and called dangerous

what is alpha bias

assuming there are real differences between males and females

what is beta bias

ignoring or minimising sex differences

how does gender bias impact Sz

diagnositc criteria tend to be applied differently to males and females

classification systems show a beta bias potentially leading to higher diagnosis of men

gender bais is also associated with the gender of the clinician

AO3 for culture and gender bias

there is a question of the reason for higher diagnosis of black americans and brits

Women may be less diagnosed due to higher functioning

There is a suggestion that psychiatrists diagnosis of Sz has culture and gender bias

there is a question of the reason for higher diagnosis of black americans and brits

some suggest Sz is more prevalent in some groups due to environmental stressors while others suggest cultural bias and blindness is the cause with a misunderstanding of cultural differences

If cultural bias is the cause, it is likely to lead mistreatment and further stereotyping

Women may be less diagnosed due to higher functioning

Cotton et al found female patients typically function better than men, being more able to work and have good relationships. This may explain the underdiagnosis in women despite similarity in symptoms

An underdiagnosis of women suggests the validity of diagnosis is poor as it is only effective for one gender

There is a suggestion that psychiatrists diagnosis of Sz has cultural and gender bias

Loring and Powel sent 290 psychiatrists 2 identical case studies but changed the gender/ race or did not disclose the gender/race

They found overdiagnosis of black case studies and underdiagnosis of females. The most accurate diagnosis was when the gender and race of the patient was the same as the psychiatrist

This suggests Sz diagnosis lacks validity as it has gender and cultural bias