Schizophrenia : Evaluation Flashcards
What is a problem with the diagnosis of schizophrenia?
Problem: THE ISSUE OF VALIDITY
- Validity refers to whether we are assessing what we are intending to assess. An important measure of validity is criterion validity – how accurately a test measures the outcomes it was designed to measure.
- Cheniaux et al. (2009) Had two psychiatrists independently diagnose 100 patients using both DSM and ICD criteria. It was found that inter-rater reliability was poor, with one psychiatrist diagnosing 26 patients with schizophrenia according to the DSM and 44 according to the ICD, whereas the other diagnosed 13 with the DSM and 24 with the ICD.
- The fact that a total of 68 patients received a diagnosis with the ICD and only 39 with the DSM demonstrates that schizophrenia is either over or under diagnoses, either way criterion validity is low.
What is a positive of the diagnosis of schizophrenia?
Positive : Good reliability
- Although historically validity and reliability of diagnosis appears to be an issue, more recent research has suggested that it has good inter-rater reliability.
- Osorio et al. (2019) reported excellent reliability, when looking at 180 schizophrenic diagnoses, when consultants were interviewed post-diagnosis, they achieved an inter-rater reliability of +.97.
- Furthermore, on a second diagnosis, the same clinician tended to come to the same diagnosis, with a test-retest reliability score of +.92.
- So this suggests that when psychiatrists are encouraged to use the same diagnostic manual, then diagnosis is consistently applied.
What is an issue of diagnosing schizophrenia?
Problem : The issue of Comorbidity
- Comorbidity refers to the fact that two or more conditions occur together. If conditions occur together a lot of the time then this calls into question the validity of the diagnosis and classification because they might actually be a single condition.
- Schizophrenia is commonly diagnosed with other conditions.
- In one review Buckley at et (2009) concluded that half (50%) of patients with schizophrenia also have a diagnosis of depression, 47% substance abuse, 29% PTSD & 23% OCD.
- This is a problem for classification because it means schizophrenia may not exist as a distinct condition and is a problem for diagnosis as it suggests that at least some people diagnosed with schizophrenia may instead have unusual cases of conditions like depression
What is a limitation of diagnosing schizophrenia?
Limitation : The Issue of symptom overlap
Another limitation of schizophrenia diagnosis is the existence of symptom overlap with other conditions.
- There is considerable overlap between the symptoms of schizophrenia and the symptoms of other conditions, for example both schizophrenia and bipolar disorder involve positive symptoms such as delusions, and negative symptoms such as avolition.
- In terms of classification this suggests that schizophrenia and bipolar may not be two different conditions but variations of a single condition. In terms of diagnosis it means that schizophrenia is hard to distinguish from bi-polar disorder.
- As with comorbidity, symptom overlap means that schizophrenia may not exist as a distinct condition and that even if it does it is hard to diagnose. So both its classification and diagnosis are flawed.
What is a limitation of the schizophrenic diagnosis?
Problem : The Issue of Gender bias
A further limitation of schizophrenia diagnosis is the existence of gender bias. Since the 1980s men have been diagnosed with schizophrenia more commonly than women.
- Cotton et al. (2009) suggest this is due to the fact that women have closer social and familial relationships than men and hence get more support.
- This leads to women with schizophrenia functioning better than men, which may explain why some women have not been diagnosed with schizophrenia where men with similar symptoms might have been; the better interpersonal functioning may bias practitioners to underdiagnose schizophrenia, either because symptoms are masked altogether or because of the quality of interpersonal functioning makes the case seem too mild to warrant a diagnosis.
- This suggests that the validity of the diagnosis of schizophrenia is poor because our procedures for diagnosis work well only on patients of one gender.
What is a limitation of the schizophrenic diagnosis?
Problem : Culture Bias
A further limitation of schizophrenia diagnosis is the existence of culture bias.
- Afro-Caribbean people living in the UK are 9 times more likely to receive a diagnosis (Pinto & Jones 2008) compared to white British people, although people living in Afro-Caribbean countries are not, ruling out a genetic vulnerability. The most likely explanation for this is culture bias in diagnosis of clients by psychiatrist from a different cultural background.
- Some symptoms of schizophrenia, particularly hearing voices, have different meanings in different cultures. For example, in some Afro-Caribbean, such as Haiti, societies voices may be attributed to communication from ancestors. However, when presented to a practitioner from a different culture, these experience may seem bizarre or irrational.
- This appears to lead to an over interpretation of symptoms in black British people (Escobar, 2012). This means the Afro-Caribbean people may be discriminated against by a culturally biased diagnostic system.
What is a strength of biological explanations of schizophrenia?
Strength : Support for gentic Vulnerability
There is now very strong evidence for genetic vulnerability to schizophrenia from a variety of sources.
- Gottesman (1991) shows how genetic similarity and shared risk of schizophrenia are closely related. Adoption studies (Tienari et al. 2004) shows that children of schizophrenia sufferers are still at heightened risk of schizophrenia if adopted into families with no history of the condition.
- Furthermore a recent study by Hilker et al. (2018) showed a concordance rate of 33% for identical twin and 7% for non-identical twins.
- These findings don’t mean that schizophrenia is entirely genetic, however it does suggest that genetic factors make some people more vulnerable to developing schizophrenia than others.
What is a weakness of the biological explanations for schizophrenia?
Weakness : Biological Determinsm
One limitation of the genetic explanation is there is clear evidence to show that environmental factors also increase the risk of developing schizophrenia.
- These environmental factors include both biological and psychological influences. Biological risk factors include birth complications (Morgan et al. 2017) and smoking THC-rich cannabis in teenage years. Psychological risk factors include childhood trauma which leaves people more vulnerable to adult mental health problems in general but there is now evidence for a particular link with schizophrenia.
- In one study by Mørkved et al. (2017), researchers found 67% of people with schizophrenia and related psychotic conditions reported at least one childhood trauma as opposed to 38% of a matched group with non-psychotic mental health problems.
This means that genetic factors alone cannot provide a complete explanation for schizophrenia.
What is a strength of the dopamine hypothesis?
Strength : Dopamine Hypothesis - Evidence from drug studies
There is support from a number of sources for abnormal dopamine functioning in schizophrenia.
- Dopamine agonists like amphetamines that increase the levels of dopamine makes schizophrenia worse and can produce schizophrenia like symptoms in non-sufferers (Curran et al. 2004). Antipsychotic drugs, on the other hand, work by reducing dopamine activity (Tauscher et al. 2014) and are used effectively with many schizophrenic patients.
- Furthermore, research has suggested that a number of candidate genes implicated in schizophrenia act on the production of DA or DA receptors
- All of this strongly suggests that dopamine is involved in the symptoms of schizophrenia.
What is a limitation of the dopamine hypothesis?
Dopamine hypothesis: The role of glutamate
One limitation of the dopamine hypothesis is evidence for a central role of glutamate.
- Post-mortem and live scanning studies have consistently found raised levels of the neurotransmitter glutamate in several brain regions of people with schizophrenia (McCutcheon et al. 2020). In addition, several candidate genes for schizophrenia are believed to be involved in glutamate production or processing.
- This means that an equally strong case can be made for a role for other neurotransmitters
