SCHIZOPHRENIA;
C1asstacat1qn or sz ·
Cl■dltloatlon: Organising symptoms into categories based on which symptomll cluster together in sufferers. (Sz atreets 1% of
the population).
Diagnosis: Deciding whether someone has a particular mental illness.
Positive symptoms: Atypical symptoms experienced In addition to normal experiences.
Hallucinations: disturbances of perception which have no basis in reality, the most common are auditory
hallucinations (hearing voices).
Delusions: Irrational beliefs which hold no basis in reality. Such as a delusion of control, which is the belief that their
body is under external control such as being controlled by the govemmenl
Negative symptoms: Atypical symptoms that represent the loss of usual experiences.
• Avolition: a lack of purposeful, willed behaviour, the inability to start or continue goal directed behaviour, results In
reduced motivation and lowered activity levels such as poor hygiene.
Speech poverty: reduced frequency and quality, often repeats words and difficulty producing them.
Reliability and valk1D in diaonnsi§lglnMificatioo of sz·
Rellablllty: is the extent to which the diagnosis Is consistent In relation to Sz. Inter-rater reliability is the extent to which different
psychiatrists diagnose the same patient with the same condition. Reliability can be affected by how the classifications for a
diagnosis have changed over time, the ICD and the DSM have had different versions over time where the symptoms for Sz
have changed. Cultural differences can also affect reliability as Western cultures see hearing voices as a sign for Sz whereas
African cultures see hearing voices as acceptable as they are hearing the voices of their ancestors or God.
Evidence from Copeland: Cultural differences affect the reliability of the diagnosis/classification of Sz as Copeland gave US
and UK psychiatrists a description of a patient and found that 69% of the US psychiatrist gave the patient a diagnosis of Sz
whereas only 2% of the UK psychiatrists gave the patent a diagnosis of Sz. Showing that the diagnosis of Sz is not
cross-culturally reliable. The classification of symptoms is also not reliable as the US uses the DSM 5 and the UK uses the ICD
11.
(·) However, this study lacks temporal validity as since this study was taken the ICD and the DSM have fallen more in line with
each other suggesting that the reliability of the diagnosis of Sz would have improved to be more consistent with each other.
Validity: is the extent to which you can measure what you intend to measure. Validity can be affected due to symptom overlap,
in which symptoms from one condition are symptoms in another condition such as avolition which is a symptom of SZ but can
also be seen as a symptom of depression. Symptom overlap can lead to co-morbidity in which two conditions coexist with each
other. Validity is therefore called into question because of this as psychiatrists are not able to tell the difference between the two
conditions meaning that they are not able to measure what they intend to, which in this case is Sz.
Evidence from Buckley: found that comorbidity lowers the validity of Sz diagnosis, as he found that 50% of patients
diagnosed with Sz were also diagnosed with depression, 47% of people diagnosed with SZ were also diagnosed with
substance abuse, this questions the validity of the classification of Sz as the classification is not just measuring SZ due to
symptom overlap means that the classification is alo measuring other conditions. This calls the validity of the diagnosis into
question as they may not be able to measure the difference between one condition to another which leads to them
misdiagnosing them.
(-) However, the comorbidity may not be due to symptom overlap but be due to it being a coping mechanism for having Sz.
Evidence from Po-II: Validity of a diagnosis of Sz is low due to gender bias. He found that when male and female ·
psychiatrists were told to diagnosis a patient which identified as 'male' or 'no information', 56% of the psychiatrists diagnosed
them with Sz, but when the patient was labelled as 'female' only 20% of the psychiatrists diagnosed them with SZ this calls into
question the validity of the diagnosis. They also found that gender bias is more present in male than female psychiatrists which
calls into question the reliability of the diagnosis as it is not consistent between the two genders so a diagnosis of SZ would
depend on the gender of the patient but also the gender of the psychiatrist.
Bi0100ical exo,anatjons t0csz·
• Genetics
• Dopamine hypothesis
• Neural correlates
Genetic explanation:
There is evidence which suggests that SZ is genetic and runs through the genes of families, so Sz can be inherited as genes
are passed from parent to child. Gottesman found that MZ twins have a 48% concordance rate of developing sz compared to
DZ twins which have a 17% concordance rate of developing Sz.
(·) However, if Sz was purely biological then you would expect a concordance rate of 100% between MZ twins and a 50%
concordance rate between DZ twins this suggests that the environment has a part to play.
C1asstacat1qn or sz ·
Cl■dltloatlon: Organising symptoms into categories based on which symptomll cluster together in sufferers. (Sz atreets 1% of
the population).
Diagnosis: Deciding whether someone has a particular mental illness.
Positive symptoms: Atypical symptoms experienced In addition to normal experiences.
Hallucinations: disturbances of perception which have no basis in reality, the most common are auditory
hallucinations (hearing voices).
Delusions: Irrational beliefs which hold no basis in reality. Such as a delusion of control, which is the belief that their
body is under external control such as being controlled by the govemmenl
Negative symptoms: Atypical symptoms that represent the loss of usual experiences.
• Avolition: a lack of purposeful, willed behaviour, the inability to start or continue goal directed behaviour, results In
reduced motivation and lowered activity levels such as poor hygiene.
Speech poverty: reduced frequency and quality, often repeats words and difficulty producing them.
Reliability and valk1D in diaonnsi§lglnMificatioo of sz·
Rellablllty: is the extent to which the diagnosis Is consistent In relation to Sz. Inter-rater reliability is the extent to which different
psychiatrists diagnose the same patient with the same condition. Reliability can be affected by how the classifications for a
diagnosis have changed over time, the ICD and the DSM have had different versions over time where the symptoms for Sz
have changed. Cultural differences can also affect reliability as Western cultures see hearing voices as a sign for Sz whereas
African cultures see hearing voices as acceptable as they are hearing the voices of their ancestors or God.
Evidence from Copeland: Cultural differences affect the reliability of the diagnosis/classification of Sz as Copeland gave US
and UK psychiatrists a description of a patient and found that 69% of the US psychiatrist gave the patient a diagnosis of Sz
whereas only 2% of the UK psychiatrists gave the patent a diagnosis of Sz. Showing that the diagnosis of Sz is not
cross-culturally reliable. The classification of symptoms is also not reliable as the US uses the DSM 5 and the UK uses the ICD
11.
(·) However, this study lacks temporal validity as since this study was taken the ICD and the DSM have fallen more in line with
each other suggesting that the reliability of the diagnosis of Sz would have improved to be more consistent with each other.
Validity: is the extent to which you can measure what you intend to measure. Validity can be affected due to symptom overlap,
in which symptoms from one condition are symptoms in another condition such as avolition which is a symptom of SZ but can
also be seen as a symptom of depression. Symptom overlap can lead to co-morbidity in which two conditions coexist with each
other. Validity is therefore called into question because of this as psychiatrists are not able to tell the difference between the two
conditions meaning that they are not able to measure what they intend to, which in this case is Sz.
Evidence from Buckley: found that comorbidity lowers the validity of Sz diagnosis, as he found that 50% of patients
diagnosed with Sz were also diagnosed with depression, 47% of people diagnosed with SZ were also diagnosed with
substance abuse, this questions the validity of the classification of Sz as the classification is not just measuring SZ due to
symptom overlap means that the classification is alo measuring other conditions. This calls the validity of the diagnosis into
question as they may not be able to measure the difference between one condition to another which leads to them
misdiagnosing them.
(-) However, the comorbidity may not be due to symptom overlap but be due to it being a coping mechanism for having Sz.
Evidence from Po-II: Validity of a diagnosis of Sz is low due to gender bias. He found that when male and female ·
psychiatrists were told to diagnosis a patient which identified as 'male' or 'no information', 56% of the psychiatrists diagnosed
them with Sz, but when the patient was labelled as 'female' only 20% of the psychiatrists diagnosed them with SZ this calls into
question the validity of the diagnosis. They also found that gender bias is more present in male than female psychiatrists which
calls into question the reliability of the diagnosis as it is not consistent between the two genders so a diagnosis of SZ would
depend on the gender of the patient but also the gender of the psychiatrist.
Bi0100ical exo,anatjons t0csz·
• Genetics
• Dopamine hypothesis
• Neural correlates
Genetic explanation:
There is evidence which suggests that SZ is genetic and runs through the genes of families, so Sz can be inherited as genes
are passed from parent to child. Gottesman found that MZ twins have a 48% concordance rate of developing sz compared to
DZ twins which have a 17% concordance rate of developing Sz.
(·) However, if Sz was purely biological then you would expect a concordance rate of 100% between MZ twins and a 50%
concordance rate between DZ twins this suggests that the environment has a part to play.
