Schizophrenia
Introduction to schizophrenia:
Diagnosis and classification of schizophrenia:
Diagnosis and classification
- To diagnose a specific disorder, we need to distinguish one disorder from another. Do this by
identifying a cluster of symptoms that occur together and classifying this as 1 disorder
- ICD-10 and DSM-5, previous editions recognised subtypes of schizophrenia, but both have
now dropped them because they tended to by inconsistent
Positive symptoms
- Hallucinations: uneasy sensory experiences, some are related to events in the environment,
but others aren’t e.g. voices heard either talking to or commenting on a person. Can be
experienced in relation to any sense.
- Delusions: also knows a paranoia, these are irrational beliefs. Common delusions involved
being an important historical or religious figure e.g., Jesus. Also commonly involved being
persecuted. Another call of delusions concerns the body, believe under external control.
Negative symptoms
- Speech poverty: changes in patterns of speech. Reduction in amount and quality of speech
and delay in response during conversation. Now more emphasis on speech disorganisation –
speech becomes incoherent, or speaker changes topic mid-sentence
- Avolition: finding it difficult to begin or keep up with goal-directed activity, sharply reduced
motivation to carry out a range of activities. Andreasen identified 3 signs of avolition: poor
hygiene and grooming, lack of persistence in work/education and lack of energ
Issues in diagnosis and classification:
Good reliability: means consistency. Psychiatric diagnosis is said to be reliable when different
diagnosing clinicians reach the same diagnosis for the same individual (inter-rater reliability) and
when the same clinician reaches the same diagnosis for the same individual on 2 occasions (test-
retest reliability). Osorio - pairs of interviewers achieved inter-rater reliability of +9.7 and test-retest
of +9.2, means we can be sure diagnosis is consistent.
Low validity: criterion validity, Cheniaux had 2 psychiatrists independently assess same 100 clients
using ICD-10 and DSM-IV, found 68 diagnosed with ICD and 39 DSM, suggests either under/over
diagnosed.
Co-morbidity: commonly diagnosed with other conditions, one review found ½ diagnosed with
schizophrenia also had diagnosis of depression/substance abuse. Means may not exist as distinct
condition.
Gender bias in diagnosis: since 1980s men diagnosed more with schizophrenia. Women may be less
vulnerable due to genetic. Cotton suggests more women underdiagnosed as they have closer
relationships hence get support. Lead to women functioning better but may not receive treatment.
Symptom overlap: schizophrenia and bipolar both have positive and negative symptoms. Terms of
classification suggests they may be a variation of a single condition, hard to distinguish so
classification and diagnosis are flawed.
, Biological explanations for schizophrenia:
Genetic basis:
Family studies
- Confirmed that risk increase with genetic similarity to a relative with disorder. Gottesman’s
large-scale family study. Identical twin with schizophrenia – 48% chance of developing it,
sibling with schizophrenia – 9% chance.
Candidate genes
- No. of diff. genes involved (polygenic), most likely genes would be those coding for
neurotransmitters including dopamine
- Ripke combined all previous data from genome-wide studies. Genetic makeup of 37000
people with schizophrenia compared to 113000 controls showed 108 separate variations of
increased risk
- Aetiologically heterogeneous – different combinations of factors, including genetic variation,
can lead to the condition
Role of mutation
- Genetic origin in absence of a family history because of disorder. Mutation in parental DNA
caused by radiation, poison, or viral infection
- Evidence for mutation comes from positive correlation between parental age and risk of
schizophrenia, increasing from 0.7% with fathers under 25 to over 2% with fathers over 50
(Brown et al.)
Evaluation:
Research support: strong evidence base. Family studies such as Gottesman show that risk increases
with genetic similarity to a family member with schizophrenia. Adoption studies such as Tienari show
that biological children of parents with schizophrenia are at heightened risk even if they grow up in
an adoptive family. This shows some people are more vulnerable to schizophrenia.
Environmental factors: clear evidence shows environmental factors increased risk of developing
schizophrenia. Factors include both biological and psychological influences. Biological risk factors
include birth complications and smoking THC-rich cannabis in teen years. Psychological risk factors
include childhood trauma, study Morkved et al. 67% of pps with schizophrenia and related disorders
reported at least 1 childhood trauma opposed to 38% of matched group with non-psychotic mental
issues.
Introduction to schizophrenia:
Diagnosis and classification of schizophrenia:
Diagnosis and classification
- To diagnose a specific disorder, we need to distinguish one disorder from another. Do this by
identifying a cluster of symptoms that occur together and classifying this as 1 disorder
- ICD-10 and DSM-5, previous editions recognised subtypes of schizophrenia, but both have
now dropped them because they tended to by inconsistent
Positive symptoms
- Hallucinations: uneasy sensory experiences, some are related to events in the environment,
but others aren’t e.g. voices heard either talking to or commenting on a person. Can be
experienced in relation to any sense.
- Delusions: also knows a paranoia, these are irrational beliefs. Common delusions involved
being an important historical or religious figure e.g., Jesus. Also commonly involved being
persecuted. Another call of delusions concerns the body, believe under external control.
Negative symptoms
- Speech poverty: changes in patterns of speech. Reduction in amount and quality of speech
and delay in response during conversation. Now more emphasis on speech disorganisation –
speech becomes incoherent, or speaker changes topic mid-sentence
- Avolition: finding it difficult to begin or keep up with goal-directed activity, sharply reduced
motivation to carry out a range of activities. Andreasen identified 3 signs of avolition: poor
hygiene and grooming, lack of persistence in work/education and lack of energ
Issues in diagnosis and classification:
Good reliability: means consistency. Psychiatric diagnosis is said to be reliable when different
diagnosing clinicians reach the same diagnosis for the same individual (inter-rater reliability) and
when the same clinician reaches the same diagnosis for the same individual on 2 occasions (test-
retest reliability). Osorio - pairs of interviewers achieved inter-rater reliability of +9.7 and test-retest
of +9.2, means we can be sure diagnosis is consistent.
Low validity: criterion validity, Cheniaux had 2 psychiatrists independently assess same 100 clients
using ICD-10 and DSM-IV, found 68 diagnosed with ICD and 39 DSM, suggests either under/over
diagnosed.
Co-morbidity: commonly diagnosed with other conditions, one review found ½ diagnosed with
schizophrenia also had diagnosis of depression/substance abuse. Means may not exist as distinct
condition.
Gender bias in diagnosis: since 1980s men diagnosed more with schizophrenia. Women may be less
vulnerable due to genetic. Cotton suggests more women underdiagnosed as they have closer
relationships hence get support. Lead to women functioning better but may not receive treatment.
Symptom overlap: schizophrenia and bipolar both have positive and negative symptoms. Terms of
classification suggests they may be a variation of a single condition, hard to distinguish so
classification and diagnosis are flawed.
, Biological explanations for schizophrenia:
Genetic basis:
Family studies
- Confirmed that risk increase with genetic similarity to a relative with disorder. Gottesman’s
large-scale family study. Identical twin with schizophrenia – 48% chance of developing it,
sibling with schizophrenia – 9% chance.
Candidate genes
- No. of diff. genes involved (polygenic), most likely genes would be those coding for
neurotransmitters including dopamine
- Ripke combined all previous data from genome-wide studies. Genetic makeup of 37000
people with schizophrenia compared to 113000 controls showed 108 separate variations of
increased risk
- Aetiologically heterogeneous – different combinations of factors, including genetic variation,
can lead to the condition
Role of mutation
- Genetic origin in absence of a family history because of disorder. Mutation in parental DNA
caused by radiation, poison, or viral infection
- Evidence for mutation comes from positive correlation between parental age and risk of
schizophrenia, increasing from 0.7% with fathers under 25 to over 2% with fathers over 50
(Brown et al.)
Evaluation:
Research support: strong evidence base. Family studies such as Gottesman show that risk increases
with genetic similarity to a family member with schizophrenia. Adoption studies such as Tienari show
that biological children of parents with schizophrenia are at heightened risk even if they grow up in
an adoptive family. This shows some people are more vulnerable to schizophrenia.
Environmental factors: clear evidence shows environmental factors increased risk of developing
schizophrenia. Factors include both biological and psychological influences. Biological risk factors
include birth complications and smoking THC-rich cannabis in teen years. Psychological risk factors
include childhood trauma, study Morkved et al. 67% of pps with schizophrenia and related disorders
reported at least 1 childhood trauma opposed to 38% of matched group with non-psychotic mental
issues.
