Classification of Schitzophrenia

Classification and a03 (how reliability and validity effect diagnosis)

What is ==Schizophrenia==

* a mental disorder suffered by ==1%== of the population, characterised by delusions, hallucinations, avolition and speech poverty
* Most common in ==men + ages 15-35==
* To be diagnosed two of following symptoms must be present for ==over a month== (one has to be a positive symptom)

What is a @@positive symptom of SZ@@

* Experiences that are @@in addition to normal functioning-@@ include hallucinations and delusions

@@Hallucinations (positive)@@

* Additional @@sensory experiences@@
* @@Unusual perceptions@@ of environment stimuli unique to the individual, no one else can perceive

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Hallucinations can be:

* @@visual@@ (seeing distortions in objects that look like faces or seeing things that aren’t there at all)
* @@auditory@@ (hearing critical voices)
* @@olfactory (@@perceiving a disgusting smell)
* @@tactile@@ (feeling something or someone)

@@Delusions (positive)@@

* @@Irrational beliefs@@ about themselves, people around them or of the world, but aren’t true in reality
* @@paranoid delusions@@ involve an individual feeling like they’re being @@persecuted by others@@ (feeling like people are out to get them/ being followed or spied on)
* @@**Delusions of grandeur**@@ involve exaggerated beliefs about oneself (being famous or having superpowers)

Negative symptoms

* involve a reduction in normal functioning
* they include avolition and speech poverty

avolition (negative)

* loss of normal motivation or energy, making it difficult to begin and maintain goal-directed behaviour
* often less sociable and less likely to look after personal hygiene
* e,g, sitting in bed all day instead of going to work which is only a short walk away

Speech Poverty

* reduction in amount or quality of verbal response e.g. brief and disorganised adding random words/ jumping from topic to topic

Speech poverty can include:

* reduced verbal fluency (difficulty saying a list of words for a given topic)
* reduced language complexity ( short utterances)

A01- %%Reliability%% in diagnosis/ classification of SZ

* the %%consistency%% of measuring the symptoms of Sz
* %%**Test-retest**%%- the extent to which a clinician makes the %%same diagnosis of Sz on separate occasions%% from the same information provided by the patient
* %%**Inter-rater-**%% the extent to which different clinicians %%independently make the same diagnosis%% of Sz when assessing the same patient

^^Culture bias^^ as an issue affecting reliability of diagnosis

* Culture bias concerns differential ^^treatment towards ethnic groups.^^ There is a tendency for members of certain ethnic minorities to be ^^over-diagnosed^^ with schizophrenia.
* For example, people of ^^Afro-Caribbean descent^^ are ^^several times^^ more likely than white people to be diagnosed with schizophrenia. This could be because the people who create diagnostic tools such as the DSM are from ^^predominately white backgrounds^^, with a ^^different set of norms and values^^ to other ethnic groups.
* Cultural bias can therefore affect the ^^inter-rater reliability^^ of diagnosis and classification because an individual reporting the same symptoms to clinicians from different cultural backgrounds may ^^not receive the same diagnosis.^^

==Evidence for culture bias== affecting reliability of diagnosis- Luhrmann

* ==Luhrmann et al.== investigated ==60 adults== (20 each from Ghana, India and US) diagnosed with schizophrenia. They used ==interviews== to ask the participants about the ==voices they heard.==
* Many of the @@Ghanaian and Indian@@ participants reported @@positive experiences,@@ whereas not one American did. The results imply that if a Ghanaian or Indian patient was to report @@hearing voices, this may be viewed as a negative experience@@ and a symptom of schizophrenia @@by an American clinician@@ but not by a clinician of their own culture.
* This could lead to low inter-rater reliability of diagnosis between clinicians of these particular cultures.

Culture bias can lead to ^^negative labels^^

* Individuals who display characteristics considered ^^abnormal by a particular culture^^, but not their own, may be labelled as a ‘schizophrenic’ by a clinician.
* They may ^^not understand^^ why they have been given this label, which can make them feel ^^ostracised from society.^^
* Furthermore, as they struggle to cope with being ‘different’, this can lead to ^^social withdrawal, avolition and disorganised thinking. A **self-fulfilling prophecy** results^^ as the behaviours that develop are because of the label they have been given.

%%Symptom overlap%% as an issue affecting reliability of diagnosis

* Symptom overlap occurs when the %%characteristics of a particular disorder are shared with another%%.
* For example, %%schizophrenia%% and %%bipolar disorder%% are often characterised by the common symptom of depressed mood.
* This can %%affect the inter-rater reliability%% of diagnosis because if a person presents the symptom of depressed mood to %%different clinicians,%% one may provide a diagnosis of schizophrenia and another with bipolar disorder.

==Evidence of symptom overlap== affecting reliability of diagnosis

* ==Ellason and Ross== gave 108 patients with a diagnosis of ==dissociative identity disorder== (DID) the ‘Positive and Negative Syndrome Scale’.
* They found that the patients actually reported more ==positive symptoms== than schizophrenic patients typically experience. The consequence for real patients with DID is they are often provided with a ==false-positive (type 1 error) diagnosis of schizophrenia== because the overlapping positive symptoms are more commonly associated with schizophrenia.
* If an initial diagnosis is provided ==without asking the patient enough questions==, this can lead to low inter-rater reliability between clinicians.

^^Inappropriate medication is a negative consequence of low inter-rater reliability due to symptom overlap^^

* An implication of the issue of symptom overlap is that it can lead to ^^misdiagnosis and consequently an incorrect therapy.^^
* For example, a schizophrenic patient with depressed mood may be misdiagnosed with bipolar disorder and receive a prescription for this disorder. This treatment may be ^^ineffective^^ and would also have ^^negative economic implications^^ for society.
* One way to deal with this issue may be to examine the ^^grey matter conten^^t of the brain, as schizophrenics can experience a ^^decrease of grey matter,^^ while bipolar sufferers do not. This shows how objective, empirical evidence can support a more unreliable diagnosis of schizophrenia based on symptoms alone.

%%Validity in the diagnosis and classification of SZ%%

* concerns the %%accuracy of measuring symptoms%% and whether classification systems can distinguish schizophrenia form other disorders.
* The validity of a diagnosis of schizophrenia can be assessed in a number of ways: 

%%· **Concurrent validity**%% is the extent to which %%different classification systems identify symptoms%% of schizophrenia according to their criteria and the systems arrive at the same diagnosis of schizophrenia. %%If both systems agree,%% the diagnosis has concurrent validity. 

%%**· Predictive validity**%% is the extent to which a diagnosis of schizophrenia %%leads to a treatment%% which is successful in reducing a patient’s symptoms. If the treatment %%outcome is successful,%% the diagnosis has predictive validity

Co-morbidty as an issue affecting reliability diagnosis

* Co-morbidity occurs when a person has two or more disorders at the same time. For example, schizophrenia is often co-morbid with disorders such as substance abuse, depression and OCD.
* This can affect the validity of classification and diagnosis because it leads to uncertainty about whether such different disorders can be considered independently or not.
* For example, schizophrenia may not always be a separate disorder to depression; depression may be a symptom of schizophrenia and therefore occur at the same time.

==Evidence of co-morbidity== affecting schizophrenia

* ==Buckley et al== reported that ==50%== ==of schizophrenics== had ==co-morbid depression==, @@47% substance abuse@@ and 23% OCD.
* This highlights the problem of trying to distinguish ==separate disorders== and that such high levels of co-morbidity might suggest that schizophrenia consists of ==distinct sub-types==.
* For example, schizophrenia with obsessive-compulsive symptoms may be one such sub-type which should be considered distinct from schizophrenia with substance abuse.

^^Schizophrenics with co-morbid disorders are excluded from research^^

* An implication of the issue of co-morbidity is that despite being the majority of patients, many ^^schizophrenics are not recognised as having the disorder.^^
* This is because a clinician may diagnose a patient with their co-morbid disorder ^^such as bi-polar^^ disorder and not recognise that they also have schizophrenia.
* This means the diagnosis is ^^invalid^^ and such patients are ^^excluded from research into schizophrenia^^ and any research findings obtained may not represent sufferers of schizophrenia with prominent co-morbid disorders.

%%gender bias as an issue affecting validity of diagnosis%%

* Gender bias refers to %%differential treatment or representation%% of males and females, based on %%stereotypes.%%
* In the context of diagnosing schizophrenia, %%males are statistically more likely to be diagnosed than females.%% However, this may misrepresent the true prevalence of the disorder for each sex.
* For instance, %%female patients%% %%typically function better%% than males when suffering with symptoms such avolition, so may %%cope or seek support%% from others.
* This affects the validity of diagnosis because clinicians may assume women who present such symptoms are not likely to be suffering from of schizophrenia and %%diagnose them with a different disorder%% such as depression

==Evidence that gender bias affects the validity of diagnosis:==

* ==Loring and Powell== randomly selected ==290 psychiatrists== and asked them to read information about two patients and diagnose them according to standard diagnostic criteria.
* When the patients were ==not assigned a gender== or described as ‘males’ ==56%== of the psychiatrists gave a diagnosis of schizophrenia compared to ==only 20% when they were described as ‘female’.==
* This shows that gender bias when interpreting symptoms can affect the validity of diagnosis.

^^Evidence for a biological basis for the under-diagnosis of females^^

* Kulkarni et al found that the female ^^sex hormone oestradiol^^ was effective in ^^treating schizophrenia in women when used as an antipsychotic therapy.^^
* This suggests that female biology naturally helps them cope better with schizophrenic symptoms than males and therefore they may be ^^less inclined to seek a clinical consultation.^^
* Biological differences between the sexes may therefore lead to under-diagnosis of females and reduce the validity of diagnoses.