Schizophrenia:
Classification of Schizophrenia:
Schizophrenia - Severe mental disorder where contact with reality and insight are impaired
● Affects 1% of population with more men being diagnosed
● Schizophrenics can completely manage disorder with treatment to allow them to live
independently
● Diagnosed using 2 diagnostic tools (DSM-5 / ICD-10)
● Symptoms are divided into Positive and Negative symptoms
● Can interfere with everyday tasks that can lead to unemployment/homelessness
Positive Symptoms - Symptoms that cause excessive behaviour
+ Hallucinations - Seeing/hearing things that are not physically there
+ Delusions of Grandeur - Thinking they are important historical/religious figures
+ Delusions of Persecution - believe they are being persecuted by government
+ Speech Disorganisation - Switching topics in same conversation
Negative Symptoms - Symptoms as a result of missing behaviour
- Speech Poverty - changes in speech patterns, often reduced
- Avolition/Apathy - difficulty in everyday tasks
Schizophrenia Diagnosis:
DSM-5:
● Schizophrenia is diagnosed if one positive symptom is present
● More commonly used in America
ICD-10:
● Schizophrenia can be diagnosed if two negative symptoms are present
● More commonly used in Europe and UK
Good diagnosis tools should be reliable and valid
Schizophrenia diagnosis has low validity but high reliability
- Cheniaux et al (2009) had two psychiatrists independently assess the same 100
clients using ICD-10 and DSM-5 criteria and found 68 were diagnosed under ICD and
39 under DSM suggesting over or underdiagnosis (low validity)
+ Osorio et al (2019) found excellent reliability for diagnosis in schizophrenia in 180
individuals using DSM-5 with pairs of interviewers achieving inter-rater reliability of +97
and test retest reliability of +92
Prior to DSM-5, diagnosis reliability was low but has now improved
+ Good reliability as diagnosis is consistent with good inter-rater and test-retest reliability
, Things that threaten validity:
● Co-morbidity - when two disorders occur together and call into question the validity
of classifying the two disorders separately. For example, Bucky et al. found 50% of
individuals with schizophrenia also have depression, 47% have co-morbidity with
substance abuse
● Symptom Overlap - when two or more conditions share symptoms and makes it hard
to diagnose and classify conditions such as bipolar
● Gender Bias - since 1980s men have been diagnosed more commonly than women
so many women go undiagnosed.
● Culture Bias - Symptoms such as hearing voices have different meanings in different
cultures. British people of African-Caribbean origin are up to nine times as likely to
receive a diagnosis as white British people although people living in African-Caribbean
countries are not
Rosenhan’s Research:
● 8 pseudopatients, (fake patients) admitted themselves to 12 different hospitals
● The pseudopatient called the hospital for an appointment. When they arrived they
complained of hearing voices saying “empty”, “hollow” and “thud”. They said that the
voices were unclear, unfamiliar and of the same sex as the pseudopatient.
● Pseudopatients gave false names, occupations and symptoms, but gave real life
histories. Once on the ward, the pseudopatients stopped pretending symptoms,
behaved normally and wrote observations. Pseudopatients were discharged only when
they convinced staff that they were sane.
● On admission, staff diagnosed 11 pseudopatients with schizophrenia, and one with
manic-depression. Staff never detected their sanity but 35 real patients detected
sanity (e.g., saying “You’re not crazy”).
● The average hospital stay was 19 days. All pseudopatients were discharged with
diagnosis of schizophrenia ‘in remission’ (still present but less severe).
● Psychiatric staff cannot always distinguish sanity from insanity. Any diagnostic method
that makes such errors cannot be very reliable or valid. However, physicians may
not identify sanity because it is less risky to diagnose a healthy person as sick than vice
versa.
Classification of Schizophrenia:
Schizophrenia - Severe mental disorder where contact with reality and insight are impaired
● Affects 1% of population with more men being diagnosed
● Schizophrenics can completely manage disorder with treatment to allow them to live
independently
● Diagnosed using 2 diagnostic tools (DSM-5 / ICD-10)
● Symptoms are divided into Positive and Negative symptoms
● Can interfere with everyday tasks that can lead to unemployment/homelessness
Positive Symptoms - Symptoms that cause excessive behaviour
+ Hallucinations - Seeing/hearing things that are not physically there
+ Delusions of Grandeur - Thinking they are important historical/religious figures
+ Delusions of Persecution - believe they are being persecuted by government
+ Speech Disorganisation - Switching topics in same conversation
Negative Symptoms - Symptoms as a result of missing behaviour
- Speech Poverty - changes in speech patterns, often reduced
- Avolition/Apathy - difficulty in everyday tasks
Schizophrenia Diagnosis:
DSM-5:
● Schizophrenia is diagnosed if one positive symptom is present
● More commonly used in America
ICD-10:
● Schizophrenia can be diagnosed if two negative symptoms are present
● More commonly used in Europe and UK
Good diagnosis tools should be reliable and valid
Schizophrenia diagnosis has low validity but high reliability
- Cheniaux et al (2009) had two psychiatrists independently assess the same 100
clients using ICD-10 and DSM-5 criteria and found 68 were diagnosed under ICD and
39 under DSM suggesting over or underdiagnosis (low validity)
+ Osorio et al (2019) found excellent reliability for diagnosis in schizophrenia in 180
individuals using DSM-5 with pairs of interviewers achieving inter-rater reliability of +97
and test retest reliability of +92
Prior to DSM-5, diagnosis reliability was low but has now improved
+ Good reliability as diagnosis is consistent with good inter-rater and test-retest reliability
, Things that threaten validity:
● Co-morbidity - when two disorders occur together and call into question the validity
of classifying the two disorders separately. For example, Bucky et al. found 50% of
individuals with schizophrenia also have depression, 47% have co-morbidity with
substance abuse
● Symptom Overlap - when two or more conditions share symptoms and makes it hard
to diagnose and classify conditions such as bipolar
● Gender Bias - since 1980s men have been diagnosed more commonly than women
so many women go undiagnosed.
● Culture Bias - Symptoms such as hearing voices have different meanings in different
cultures. British people of African-Caribbean origin are up to nine times as likely to
receive a diagnosis as white British people although people living in African-Caribbean
countries are not
Rosenhan’s Research:
● 8 pseudopatients, (fake patients) admitted themselves to 12 different hospitals
● The pseudopatient called the hospital for an appointment. When they arrived they
complained of hearing voices saying “empty”, “hollow” and “thud”. They said that the
voices were unclear, unfamiliar and of the same sex as the pseudopatient.
● Pseudopatients gave false names, occupations and symptoms, but gave real life
histories. Once on the ward, the pseudopatients stopped pretending symptoms,
behaved normally and wrote observations. Pseudopatients were discharged only when
they convinced staff that they were sane.
● On admission, staff diagnosed 11 pseudopatients with schizophrenia, and one with
manic-depression. Staff never detected their sanity but 35 real patients detected
sanity (e.g., saying “You’re not crazy”).
● The average hospital stay was 19 days. All pseudopatients were discharged with
diagnosis of schizophrenia ‘in remission’ (still present but less severe).
● Psychiatric staff cannot always distinguish sanity from insanity. Any diagnostic method
that makes such errors cannot be very reliable or valid. However, physicians may
not identify sanity because it is less risky to diagnose a healthy person as sick than vice
versa.
