SCHIZOPHRENIA
A mental disorder where contact with reality and insight are impaired, an example of
psychosis.
Diagnosis & Classification
The classification of a mental disorder is the process of organising symptoms into categories
based on which symptoms frequently cluster together.
After classification, diagnosis is possible by identifying symptoms and deciding what disorder
a person has.
The two major classification systems are the World Health Organisation’s ICD and the
American Psychiatric Association’s DSM. DSM requires 1 positive symptom for diagnosis of
SCZ whereas 2 or more negative symptoms are sufficient under ICD.
Previous editions of the ICD and DSM recognized subtypes of SCZ however these tended to
be inconsistent, so they scrapped them.
Positive symptoms
-additional experiences beyond those of ordinary existence
Hallucinations – unusual sensory experiences, some related to the events in the
environment, some bear no relationship to what the senses pick up from the environment,
can be experiences in relation to any sense, e.g., seeing distorted faces, hearing voices.
Delusions – irrational beliefs, paranoia that has no basis in reality, common delusions involve
being an important historical, political, or religious figure, also commonly involve being
persecuted or a person may believe they are under external control.
(Speech disorganisation – speech becomes incoherent or the speaker changes topic mid-
sentence)
Negative symptoms
-the loss of usual abilities and experiences
Speech poverty – changes in pattern of speech, reduction in amount and quality of speech,
accompanied by a delay in the person’s verbal responses during conversation.
Avolition – finding it difficult to begin or keep up with goal-directed activity, sharply reduced
motivation, e.g., poor hygiene and grooming, lack of persistence in work or education and
lack of energy.
GOOD RELIABILITY
Reports show excellent reliability for the diagnosis of SCZ in 180 individuals using the DSM-5.
Inter-rater reliability of +0.97 and test-retest reliability of +0.92.
LOW VALIDITY
(Criterion validity- are we assessing what we are trying to assess?) A study had 2
psychiatrists independently assess the same 100 clients under the ICD-10 and DSM-IV
criteria and found that 68 were diagnosed with SCZ under the ICD system and 39 under
DSM, suggesting SCZ is either over- or underdiagnosed and the criterion validity is low. Also
Rosenhan’s ‘being sane in insane places’ where people were admitted to psychiatric
hospitals after faking one positive symptom undermines the credibility of the diagnosis and
classification process entirely.
, C/A: In the study above, there was excellent inter-rater reliability when the clinicians used
the same D&C system, meaning that the criterion validity for diagnosing SCZ is actually good,
provided it takes place within a single diagnostic system.
CO-MORBIDITY
(The occurrence of 2 disorders or conditions together, where the two conditions are
frequently diagnosed together. Calls into question the validity of classifying them separately)
SCZ is commonly diagnosed with depression or substance abuse, suggesting SCZ may not
exist as a distinct condition, that some people diagnosed may just have unusual cases of
depression.
GENDER BIAS IN DIAGNOSIS
Since the 80s, men have been diagnosed with SCZ more commonly than women. One
explanation is that women are less vulnerable than men, perhaps due to genetics but it
seems more likely that it is because women have closer relationships and hence get support,
leading to women with SCZ functioning better than their male counterparts. This
underdiagnosis is a gender bias and means women may not be receiving sufficient treatment
and services that may benefit them.
CULTURE BIAS IN DIAGNOSIS
Some symptoms of SCZ – like hearing voices – have different meanings in different cultures,
e.g., in Haiti, people believe voices are communications from ancestors. British people of
Afro-Caribbean origin are up to 9x more likely to receive a diagnosis as white British people,
although people living in Afro-Caribbean countries are not, ruling out a genetic vulnerability.
The most likely explanation is culture bias – there is an overinterpretation of symptoms in
black British people, leading to potential discrimination.
SYMPTOM OVERLAP
Both SCZ and Bipolar Disorder involve symptoms such as delusions and avolition. In terms of
classification, this suggests that SCZ and BPD may not be 2 different conditions but rather
variations of a single condition. In terms of diagnosis, it makes SCZ hard to distinguish from
BPD. As with co-morbidity, symptom overlap means SCZ 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.
A mental disorder where contact with reality and insight are impaired, an example of
psychosis.
Diagnosis & Classification
The classification of a mental disorder is the process of organising symptoms into categories
based on which symptoms frequently cluster together.
After classification, diagnosis is possible by identifying symptoms and deciding what disorder
a person has.
The two major classification systems are the World Health Organisation’s ICD and the
American Psychiatric Association’s DSM. DSM requires 1 positive symptom for diagnosis of
SCZ whereas 2 or more negative symptoms are sufficient under ICD.
Previous editions of the ICD and DSM recognized subtypes of SCZ however these tended to
be inconsistent, so they scrapped them.
Positive symptoms
-additional experiences beyond those of ordinary existence
Hallucinations – unusual sensory experiences, some related to the events in the
environment, some bear no relationship to what the senses pick up from the environment,
can be experiences in relation to any sense, e.g., seeing distorted faces, hearing voices.
Delusions – irrational beliefs, paranoia that has no basis in reality, common delusions involve
being an important historical, political, or religious figure, also commonly involve being
persecuted or a person may believe they are under external control.
(Speech disorganisation – speech becomes incoherent or the speaker changes topic mid-
sentence)
Negative symptoms
-the loss of usual abilities and experiences
Speech poverty – changes in pattern of speech, reduction in amount and quality of speech,
accompanied by a delay in the person’s verbal responses during conversation.
Avolition – finding it difficult to begin or keep up with goal-directed activity, sharply reduced
motivation, e.g., poor hygiene and grooming, lack of persistence in work or education and
lack of energy.
GOOD RELIABILITY
Reports show excellent reliability for the diagnosis of SCZ in 180 individuals using the DSM-5.
Inter-rater reliability of +0.97 and test-retest reliability of +0.92.
LOW VALIDITY
(Criterion validity- are we assessing what we are trying to assess?) A study had 2
psychiatrists independently assess the same 100 clients under the ICD-10 and DSM-IV
criteria and found that 68 were diagnosed with SCZ under the ICD system and 39 under
DSM, suggesting SCZ is either over- or underdiagnosed and the criterion validity is low. Also
Rosenhan’s ‘being sane in insane places’ where people were admitted to psychiatric
hospitals after faking one positive symptom undermines the credibility of the diagnosis and
classification process entirely.
, C/A: In the study above, there was excellent inter-rater reliability when the clinicians used
the same D&C system, meaning that the criterion validity for diagnosing SCZ is actually good,
provided it takes place within a single diagnostic system.
CO-MORBIDITY
(The occurrence of 2 disorders or conditions together, where the two conditions are
frequently diagnosed together. Calls into question the validity of classifying them separately)
SCZ is commonly diagnosed with depression or substance abuse, suggesting SCZ may not
exist as a distinct condition, that some people diagnosed may just have unusual cases of
depression.
GENDER BIAS IN DIAGNOSIS
Since the 80s, men have been diagnosed with SCZ more commonly than women. One
explanation is that women are less vulnerable than men, perhaps due to genetics but it
seems more likely that it is because women have closer relationships and hence get support,
leading to women with SCZ functioning better than their male counterparts. This
underdiagnosis is a gender bias and means women may not be receiving sufficient treatment
and services that may benefit them.
CULTURE BIAS IN DIAGNOSIS
Some symptoms of SCZ – like hearing voices – have different meanings in different cultures,
e.g., in Haiti, people believe voices are communications from ancestors. British people of
Afro-Caribbean origin are up to 9x more likely to receive a diagnosis as white British people,
although people living in Afro-Caribbean countries are not, ruling out a genetic vulnerability.
The most likely explanation is culture bias – there is an overinterpretation of symptoms in
black British people, leading to potential discrimination.
SYMPTOM OVERLAP
Both SCZ and Bipolar Disorder involve symptoms such as delusions and avolition. In terms of
classification, this suggests that SCZ and BPD may not be 2 different conditions but rather
variations of a single condition. In terms of diagnosis, it makes SCZ hard to distinguish from
BPD. As with co-morbidity, symptom overlap means SCZ 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.
