SCHIZOPHRENIA
CLASSIFICATION + DIAGNOSIS OF SCHIZOPHRENIA
AO1
Schizophrenia: a severe mental disorder in which cognitive and
emotional functions are impaired - example of psychosis
Classification: grouping symptoms to distinguish one disorder from
others
Diagnosis: two main systems
o DSM5: requires 1+ positive symptoms, generally used in US
o ICD11: requires 2+ negative symptoms, generally used in UK
Symptoms:
POSITIVE SYMPTOMS - excess or distortion of normal functions
o Delusions - bizarre beliefs that seem real but are not, e.g. delusions of
grandeur/delusions of persecution
o Hallucinations - bizarre, unreal perceptions of the environment (auditory,
visual, olfactory)
o Thought disorders - thoughts/actions perceived as under external control
NEGATIVE SYMPTOMS - reduction/loss of normal functions
o Affective flattening - a reduction in range/intensity of emotional expression
o Speech poverty - lessening of speech fluency/productivity
o Avolition - inability to initiate goal-directed behaviour (lack of energy, poor
hygiene, lack of persistence)
AO3
Gender bias: men are more likely to be diagnosed than women (1:1.4)
which some say is due to biological differences but is more likely due to
stronger female relationships with those around them (so the ‘typical’
symptoms are not displayed as often). Limited diagnosis of schizophrenia
in females leads to a lack of support
Cultural bias: characteristics which are commonly perceived as unnatural
in Western society may be normalised in other cultures, particularly
auditory hallucinations. This could result in overdiagnosis of those of
differing cultures and painting them out to be abnormal when they do not
possess unnatural characteristics, resulting in discrimination from the
diagnostic system
Good reliability: Osorio et al found inter-rater reliability of 0.97 and test
retest reliability of 0.92 , suggesting diagnosis of schizophrenia is
consistently applied
Counterpoint: lacks validity, particularly between diagnosis systems
(criterion reliability) as Cheniaux et al showed of 100 clients sent to 2
psychiatrists using different diagnostic systems, 68 were diagnosed as
schizophrenic using the ICD10 and only 39 under the DSM5
Symptom overlap, particularly with conditions such as bipolar disorder,
raises questions of whether schizophrenia is an individual disorder or
instead an extension of other disorders, and whether it has been correctly
categorised. Similar issues of co-morbidity, where other disorders seem
, to come in line with schizophrenia - could schizophrenia be an unusual
case of depression for example??
BIOLOGICAL EXPLANATIONS FOR SCHIZOPHRENIA
GENETIC BASIS
AO1
Likelihood of developing Schizophrenia increases in line with genetic
similarity to a relative with the disorder
o Studies such as Gottesman's large-scale family study exemplifies
this; 2% risk for aunt of schizophrenic, 17% for DZ twins, 48% for
MZ twins
o Important to note family members often share environments
Genes implicated in schizophrenia are called candidate genes because
they make individuals vulnerable to later developing schizophrenia but
don’t mean they inevitably will
o Schizophrenia is polygenic, and the implicated genes are likely
those involved in dopamine neurotransmission (+others)
o Schizophrenia is said to be aetiologically heterogenous as diff
combinations of genetic variations could lead to the disorder
Mutation in parental DNA, which could be random or caused by
radiation/poison/viral infection, could also correlate with schizophrenia in
offspring
AO3
Twin/adoption studies to isolate nature/nurture: Tienari found an
increased risk of developing schizophrenia in those with schizophrenic
parents even when adopted, Hilker found a concordance rate of 33% for
MZ twins and 7% for DZ. Twin studies allow assessment
Counterpoint: never 100% concordance so must be other factors
involved, twins may not have exactly same environment as assumed
(biologically reductionist)
Ripke et al: combines data of genome wide studies of schizophrenia,
genetic makeup of 37,000 with schizophrenia was compared to 113,000
controls + 108 genetic variations were associated with an increased risk of
schizophrenia
Application - Genetic counselling could be allocated to those who are
most heavily genetically disposed to developing schizophrenia +
preventative measures
NEURAL CORRELATES
AO1
The original dopamine hypothesis: Hyperdopaminergia
o Too much dopamine/too many dopamine receiving neurons in
subcortical regions of the brain results in a distortion in attention
and perception causing hallucinations
o Believed as antipsychotic caused Parkinson's-like symptoms, a
condition resulting from low dopamine levels in the brain
Updated dopamine hypothesis: Hypodopaminergia
o Schizophrenia can also be linked to low levels of dopamine, which
are linked to disordered thinking
CLASSIFICATION + DIAGNOSIS OF SCHIZOPHRENIA
AO1
Schizophrenia: a severe mental disorder in which cognitive and
emotional functions are impaired - example of psychosis
Classification: grouping symptoms to distinguish one disorder from
others
Diagnosis: two main systems
o DSM5: requires 1+ positive symptoms, generally used in US
o ICD11: requires 2+ negative symptoms, generally used in UK
Symptoms:
POSITIVE SYMPTOMS - excess or distortion of normal functions
o Delusions - bizarre beliefs that seem real but are not, e.g. delusions of
grandeur/delusions of persecution
o Hallucinations - bizarre, unreal perceptions of the environment (auditory,
visual, olfactory)
o Thought disorders - thoughts/actions perceived as under external control
NEGATIVE SYMPTOMS - reduction/loss of normal functions
o Affective flattening - a reduction in range/intensity of emotional expression
o Speech poverty - lessening of speech fluency/productivity
o Avolition - inability to initiate goal-directed behaviour (lack of energy, poor
hygiene, lack of persistence)
AO3
Gender bias: men are more likely to be diagnosed than women (1:1.4)
which some say is due to biological differences but is more likely due to
stronger female relationships with those around them (so the ‘typical’
symptoms are not displayed as often). Limited diagnosis of schizophrenia
in females leads to a lack of support
Cultural bias: characteristics which are commonly perceived as unnatural
in Western society may be normalised in other cultures, particularly
auditory hallucinations. This could result in overdiagnosis of those of
differing cultures and painting them out to be abnormal when they do not
possess unnatural characteristics, resulting in discrimination from the
diagnostic system
Good reliability: Osorio et al found inter-rater reliability of 0.97 and test
retest reliability of 0.92 , suggesting diagnosis of schizophrenia is
consistently applied
Counterpoint: lacks validity, particularly between diagnosis systems
(criterion reliability) as Cheniaux et al showed of 100 clients sent to 2
psychiatrists using different diagnostic systems, 68 were diagnosed as
schizophrenic using the ICD10 and only 39 under the DSM5
Symptom overlap, particularly with conditions such as bipolar disorder,
raises questions of whether schizophrenia is an individual disorder or
instead an extension of other disorders, and whether it has been correctly
categorised. Similar issues of co-morbidity, where other disorders seem
, to come in line with schizophrenia - could schizophrenia be an unusual
case of depression for example??
BIOLOGICAL EXPLANATIONS FOR SCHIZOPHRENIA
GENETIC BASIS
AO1
Likelihood of developing Schizophrenia increases in line with genetic
similarity to a relative with the disorder
o Studies such as Gottesman's large-scale family study exemplifies
this; 2% risk for aunt of schizophrenic, 17% for DZ twins, 48% for
MZ twins
o Important to note family members often share environments
Genes implicated in schizophrenia are called candidate genes because
they make individuals vulnerable to later developing schizophrenia but
don’t mean they inevitably will
o Schizophrenia is polygenic, and the implicated genes are likely
those involved in dopamine neurotransmission (+others)
o Schizophrenia is said to be aetiologically heterogenous as diff
combinations of genetic variations could lead to the disorder
Mutation in parental DNA, which could be random or caused by
radiation/poison/viral infection, could also correlate with schizophrenia in
offspring
AO3
Twin/adoption studies to isolate nature/nurture: Tienari found an
increased risk of developing schizophrenia in those with schizophrenic
parents even when adopted, Hilker found a concordance rate of 33% for
MZ twins and 7% for DZ. Twin studies allow assessment
Counterpoint: never 100% concordance so must be other factors
involved, twins may not have exactly same environment as assumed
(biologically reductionist)
Ripke et al: combines data of genome wide studies of schizophrenia,
genetic makeup of 37,000 with schizophrenia was compared to 113,000
controls + 108 genetic variations were associated with an increased risk of
schizophrenia
Application - Genetic counselling could be allocated to those who are
most heavily genetically disposed to developing schizophrenia +
preventative measures
NEURAL CORRELATES
AO1
The original dopamine hypothesis: Hyperdopaminergia
o Too much dopamine/too many dopamine receiving neurons in
subcortical regions of the brain results in a distortion in attention
and perception causing hallucinations
o Believed as antipsychotic caused Parkinson's-like symptoms, a
condition resulting from low dopamine levels in the brain
Updated dopamine hypothesis: Hypodopaminergia
o Schizophrenia can also be linked to low levels of dopamine, which
are linked to disordered thinking
