AO1 DSM ICD schizophrenia classification
Schizophrenia diagnosed using DSM-5 and ICD-11 criteria based on symptom clusters and duration requirements.
AO3 Classification systems evaluation
✔ Standardised diagnosis worldwide
✔ Allows research consistency
✖ Different criteria between systems
✖ Cultural bias possible
AO1 Positive symptoms schizophrenia
Added experiences such as hallucinations and delusions that distort perception of reality.
AO1 Negative symptoms schizophrenia
Loss of normal functioning such as avolition and speech poverty reducing motivation and communication.
It includes two types: test-retest reliability and inter-rater reliability.
AO1 Reliability schizophrenia diagnosis
Reliability means consistent diagnosis across clinicians and time using classification systems.
It assesses the stability of a diagnosis over time.
AO3 Reliability evaluation
✔ Standard manuals improve agreement
✔ Kappa scores measurable
✖ Cultural bias reduces reliability
✖ Comorbidity complicates diagnosis
It is measured by a statistic called a ‘kappa score’.
AO1 Validity schizophrenia diagnosis
Validity refers to accuracy of schizophrenia as a distinct disorder with specific symptoms.
A score of 1 indicates perfect agreement, while 0 indicates no agreement.
AO3 Validity evaluation
✔ Some criteria correlations
✔ Predictive treatment value
✖ Symptom overlap disorders
✖ Gender bias diagnosis
Culture bias can lead to over-diagnosis of schizophrenia in members of other cultures.
AO1 Symptom overlap schizophrenia
Schizophrenia shares symptoms with depression and bipolar disorder, complicating classification.
Ghanaian and Indian subjects reported positive experiences with hallucinations, unlike American subjects.
AO3 Symptom overlap evaluation
✔ Explains diagnostic difficulty
✔ Supported by comorbidity
✖ Threatens validity
✖ Misdiagnosis risk
This pattern is not observed in Caribbean or African countries, suggesting context dependency.
AO1 Cultural bias schizophrenia diagnosis
Diagnosis influenced by cultural interpretation of hallucinations and clinician background.
This bias threatens the reliability of diagnosis across different cultural backgrounds.
AO3 Cultural bias evaluation
✔ Cross-cultural symptom differences
✔ Explains overdiagnosis minorities
✖ Hard to separate culture
✖ Reduces reliability
It is common among patients with schizophrenia.
AO1 Gender bias schizophrenia diagnosis
Men diagnosed more often; differences in symptoms and clinician expectations affect diagnosis.
These comorbidities complicate the reliability of schizophrenia diagnosis.
AO3 Gender bias evaluation
✔ Different symptom patterns
✔ Treatment differences evidence
✖ May reflect real prevalence
✖ Threatens validity
It can lead to lower functioning and complicate symptom interpretation.
AO1 Genetics schizophrenia explanation
Schizophrenia risk is inherited and polygenic. Higher concordance in identical twins and biological relatives shows genetic vulnerability.
These may be used for self-medication, complicating diagnosis.
AO3 Genetics evaluation
✔ Twin/adoption support genetic role
✔ Candidate genes identified
✖ Concordance not 100%
✖ Environmental factors involved
This exclusion may lead to unreliable findings regarding the causes of schizophrenia.
AO1 Dopamine imbalance schizophrenia
High dopamine in subcortex → positive symptoms. Low dopamine in prefrontal cortex → negative symptoms.
AO3 Dopamine hypothesis evaluation
✔ Drug & brain scan support
✔ Amphetamine increases symptoms
✖ Other neurotransmitters involved
✖ Slow drug response unexplained
AO1 Brain abnormalities schizophrenia
Abnormal brain areas linked to symptoms: prefrontal cortex (cognition), ventral striatum (motivation), temporal cortex (hallucinations).
AO3 Neural correlates evaluation
✔ fMRI/CT objective evidence
✔ Symptom–brain links shown
✖ Correlation not causation
✖ Not all patients abnormal
AO1 Family dysfunction schizophrenia
Schizophrenia linked to disturbed family relationships: double-bind communication, high expressed emotion, schizophrenogenic mother.
AO3 Family dysfunction evaluation
✔ EE predicts relapse
✔ Some communication studies support
✖ Causation unclear
✖ Parent-blaming socially sensitive
AO1 Psychological Cognitive deficits schizophrenia
Faulty information processing and metacognition cause hallucinations and delusions; reasoning and perception deficits.
AO3 Cognitive explanation evaluation
✔ Cognitive deficits demonstrated
✔ CBT effectiveness supports
✖ Cause of deficits unclear
✖ Ignores biology factors
