Biological explanations for schizophrenia
Genetic basis – Family studies by Gottesman confirmed that risk of schizophrenia increases with genetic similarity to relative with the disorder. Aunt (2%),
Schizophrenia sibling (9%), identical twin (48%). May also be due to environment as family often share environment. Schizophrenia is polygenic. Most likely genes are those
coding for neurotransmitters including dopamine. Ripke compared the genetic make-up of 37,000 people with a diagnosis of schizophrenia to 113,000 without.
108 separate genetic variations associated with increased risk of schizophrenia. It is aetiologically heterogenous meaning different combinations of factors
contribute. Schizophrenia can also have genetic origin without family history. E.g. mutation in DNA due to radiation, poison of infection. Age can also
contribute 2% risk in father 50+ but only 0.7% in those below 25.
Introduction to schizophrenia
- Evidence. Twin study showed a concordance rate of 33% for identical twins and 7% for non-identical.
A serious mental disorder experience by about 1% of people.
- Evidence for environmental factors. Biological risk factors include birth complication, smoking weed. Psychological risk factors include childhood
To diagnose a disorder, must distinguish one disorder from another by clusters
trauma. 67% of people with schizophrenia reported at least one childhood trauma opposed to 38% of a matched group.
of symptoms and classifying as one disorder. Diagnosis is then possible by
- Genetic counselling. Risk estimate is just an average figure and cannot reflect probability of child developing schizophrenia.
identifying symptoms. Systems of classification: ICD-10 and DSM-5. DSM-5
Neural correlates – Dopamine is important in the functioning of several brain systems related to the symptoms of schizophrenia. Original hypothesis was based
positive must be present. ICD only 2+ negative symptoms.
on discovery that drugs used to treat schizophrenia caused symptoms similar to Parkinson’s (low DA level). Schizophrenia may be as result of high levels of DA
Positive symptoms of schizophrenia are additional experiences beyond those
in subcortical areas of the brain. May explain symptoms such as speech poverty and auditory hallucinations. Davis proposed addition of cortical
of ordinary existence. Hallucinations are unusual sensory experiences. Some
hypodopaminergia in brain’s cortex. Low DA in prefrontal cortex could explain cognitive problems. It is also thought that this could lead to subcortical
are related to events in the environment while others bear no relation to what
hyperdopaminergia. Current versions of dopamine hypothesis try to explain origins of abnormal DA functions. E.g. how genetic variation and early experience
senses pick up. Delusions are irrational beliefs. Common delusions involve
can make people more sensitive to cortical hypodopaminergia.
being an important historical, political, or religious figure. A person may
- Amphetamines increase DA and worse symptoms. Antipsychotic drugs reduce DA and symptoms. Suggests dopamine involved in symptoms.
believe they are under external control. Delusions make people behave in
- Evidence for role of glutamate. Post-mortem and live scanning found raised levels of glutamate in people with schizophrenia.
ways that make sense to them but seem abnormal to others.
- Tenn induced schizophrenia-like symptoms using amphetamines and relieved them using drugs that reduced DA. Other drugs that increase DA
Negative symptoms involve loss of usual experiences. Speech poverty involves
levels do not cause schizophrenia-like symptoms.
changes in patterns of speech. This is sometimes accompanied by a delay in
the person’s verbal responses. Speech disorganisation is also significant when
speech becomes incoherent or changes topic mid-sentence. Speech Psychological explanations for schizophrenia
disorganisation, however, is classified as positive. Avolition is described as Family dysfunction - Fromm-Reichmann proposed psychodynamic explanation based on childhood accounts from patients. Noted that many patients spoke of
finding difficulty to begin or keep up with goal-directed activity. Andreasen parent she called the schizophrenogenic mother (is cold, rejecting, controlling and creates tension and secrecy). Leads to development of paranoid delusions +
identified 3 signs of avolition: poor hygiene, lack of persistence in work and schizophrenia. Double-bind theory (Bateson) emphasised role of communication style within a family. Developing child finds themselves in situations where
lack of energy. they fear doing wrong but receive mixed messages on what this is. When they get it wrong, they are punished with love withdrawal. This can lead to a
- Diagnosis reliable. Inter-rater reliability of +.97 and test-retest +.92 confusing understanding of the world and disorganised thinking and paranoid delusions. Bateson considered this a risk factor to developing schizophrenia.
- Validity. 2 psychiatrists independently assessed 100 clients using Expressed emotion is the level of emotion expressed towards a person with schizophrenia. EE contains verbal criticism, sometimes accompanied by violence,
ICD and DSM found 68 with ICD and 39 with DSM. Suggests hostility and emotional overinvolvement. These can be serious sources of stress. This is a primary explanation of relapse but may also be a trigger of onset
under/over diagnosis depending on classification used. schizophrenia for someone who is already vulnerable.
- Co-morbidity. Half with schizophrenia also had depression or - Evidence. Adults with schizophrenia are disproportionately likely to have insecure attachment. 69% women + 59% men with schizophrenia have
substance abuse. Make diagnosis more difficult. history of physical or sexual abuse.
- Gender bias. Men more commonly diagnosed most likely due to - No evidence to support traditional family-based theories. Based on clinical observation and informal assessment.
women functioning better. Means they may not receive treatment - Socially sensitive research can lead to parent-blaming. Adds insult to injury for parents.
and services that benefit them. Cognitive explanations – focuses on mental processes. Schizophrenia characterised by disruption to normal thought processing. Reduced thought processing
- Cultural bias. Symptoms have different meanings in different in ventral striatum associated with negative symptoms. Reduced processing in temporal and cingulate gyri associated with hallucination. Frith–
cultures. E.g. Haiti believe hearing voices is communications from metarepresentation (cognitive ability to reflect on thoughts. Dysfunction leads to not being able to distinguish our own actions as being carried out by
ancestors. Black British people 9x more likely to be diagnosed than ourselves e.g. hallucinations, voices, delusions. Frith also identified issues with cognitive ability to suppress automatic responses. Speech poverty could result in
white british although people living in African-Caribbean countries an inability to supress automatic thought which can lead to derailment as each word triggers associations and automatic responses.
are not. Overinterpretation of symptoms in black British people. - Evidence. 30 people with schizophrenia and 30 without compared. Stroop test. People with schizophrenia took longer to name font-colours.
Culturally biased diagnostic system. - Only explain proximal origins of symptoms. Not understood how genetics and childhood may impact metarepresentation or central control.
- Abnormal cognition may be due to genetic meaning schizophrenia is biological rather than cognitive.
Genetic basis – Family studies by Gottesman confirmed that risk of schizophrenia increases with genetic similarity to relative with the disorder. Aunt (2%),
Schizophrenia sibling (9%), identical twin (48%). May also be due to environment as family often share environment. Schizophrenia is polygenic. Most likely genes are those
coding for neurotransmitters including dopamine. Ripke compared the genetic make-up of 37,000 people with a diagnosis of schizophrenia to 113,000 without.
108 separate genetic variations associated with increased risk of schizophrenia. It is aetiologically heterogenous meaning different combinations of factors
contribute. Schizophrenia can also have genetic origin without family history. E.g. mutation in DNA due to radiation, poison of infection. Age can also
contribute 2% risk in father 50+ but only 0.7% in those below 25.
Introduction to schizophrenia
- Evidence. Twin study showed a concordance rate of 33% for identical twins and 7% for non-identical.
A serious mental disorder experience by about 1% of people.
- Evidence for environmental factors. Biological risk factors include birth complication, smoking weed. Psychological risk factors include childhood
To diagnose a disorder, must distinguish one disorder from another by clusters
trauma. 67% of people with schizophrenia reported at least one childhood trauma opposed to 38% of a matched group.
of symptoms and classifying as one disorder. Diagnosis is then possible by
- Genetic counselling. Risk estimate is just an average figure and cannot reflect probability of child developing schizophrenia.
identifying symptoms. Systems of classification: ICD-10 and DSM-5. DSM-5
Neural correlates – Dopamine is important in the functioning of several brain systems related to the symptoms of schizophrenia. Original hypothesis was based
positive must be present. ICD only 2+ negative symptoms.
on discovery that drugs used to treat schizophrenia caused symptoms similar to Parkinson’s (low DA level). Schizophrenia may be as result of high levels of DA
Positive symptoms of schizophrenia are additional experiences beyond those
in subcortical areas of the brain. May explain symptoms such as speech poverty and auditory hallucinations. Davis proposed addition of cortical
of ordinary existence. Hallucinations are unusual sensory experiences. Some
hypodopaminergia in brain’s cortex. Low DA in prefrontal cortex could explain cognitive problems. It is also thought that this could lead to subcortical
are related to events in the environment while others bear no relation to what
hyperdopaminergia. Current versions of dopamine hypothesis try to explain origins of abnormal DA functions. E.g. how genetic variation and early experience
senses pick up. Delusions are irrational beliefs. Common delusions involve
can make people more sensitive to cortical hypodopaminergia.
being an important historical, political, or religious figure. A person may
- Amphetamines increase DA and worse symptoms. Antipsychotic drugs reduce DA and symptoms. Suggests dopamine involved in symptoms.
believe they are under external control. Delusions make people behave in
- Evidence for role of glutamate. Post-mortem and live scanning found raised levels of glutamate in people with schizophrenia.
ways that make sense to them but seem abnormal to others.
- Tenn induced schizophrenia-like symptoms using amphetamines and relieved them using drugs that reduced DA. Other drugs that increase DA
Negative symptoms involve loss of usual experiences. Speech poverty involves
levels do not cause schizophrenia-like symptoms.
changes in patterns of speech. This is sometimes accompanied by a delay in
the person’s verbal responses. Speech disorganisation is also significant when
speech becomes incoherent or changes topic mid-sentence. Speech Psychological explanations for schizophrenia
disorganisation, however, is classified as positive. Avolition is described as Family dysfunction - Fromm-Reichmann proposed psychodynamic explanation based on childhood accounts from patients. Noted that many patients spoke of
finding difficulty to begin or keep up with goal-directed activity. Andreasen parent she called the schizophrenogenic mother (is cold, rejecting, controlling and creates tension and secrecy). Leads to development of paranoid delusions +
identified 3 signs of avolition: poor hygiene, lack of persistence in work and schizophrenia. Double-bind theory (Bateson) emphasised role of communication style within a family. Developing child finds themselves in situations where
lack of energy. they fear doing wrong but receive mixed messages on what this is. When they get it wrong, they are punished with love withdrawal. This can lead to a
- Diagnosis reliable. Inter-rater reliability of +.97 and test-retest +.92 confusing understanding of the world and disorganised thinking and paranoid delusions. Bateson considered this a risk factor to developing schizophrenia.
- Validity. 2 psychiatrists independently assessed 100 clients using Expressed emotion is the level of emotion expressed towards a person with schizophrenia. EE contains verbal criticism, sometimes accompanied by violence,
ICD and DSM found 68 with ICD and 39 with DSM. Suggests hostility and emotional overinvolvement. These can be serious sources of stress. This is a primary explanation of relapse but may also be a trigger of onset
under/over diagnosis depending on classification used. schizophrenia for someone who is already vulnerable.
- Co-morbidity. Half with schizophrenia also had depression or - Evidence. Adults with schizophrenia are disproportionately likely to have insecure attachment. 69% women + 59% men with schizophrenia have
substance abuse. Make diagnosis more difficult. history of physical or sexual abuse.
- Gender bias. Men more commonly diagnosed most likely due to - No evidence to support traditional family-based theories. Based on clinical observation and informal assessment.
women functioning better. Means they may not receive treatment - Socially sensitive research can lead to parent-blaming. Adds insult to injury for parents.
and services that benefit them. Cognitive explanations – focuses on mental processes. Schizophrenia characterised by disruption to normal thought processing. Reduced thought processing
- Cultural bias. Symptoms have different meanings in different in ventral striatum associated with negative symptoms. Reduced processing in temporal and cingulate gyri associated with hallucination. Frith–
cultures. E.g. Haiti believe hearing voices is communications from metarepresentation (cognitive ability to reflect on thoughts. Dysfunction leads to not being able to distinguish our own actions as being carried out by
ancestors. Black British people 9x more likely to be diagnosed than ourselves e.g. hallucinations, voices, delusions. Frith also identified issues with cognitive ability to suppress automatic responses. Speech poverty could result in
white british although people living in African-Caribbean countries an inability to supress automatic thought which can lead to derailment as each word triggers associations and automatic responses.
are not. Overinterpretation of symptoms in black British people. - Evidence. 30 people with schizophrenia and 30 without compared. Stroop test. People with schizophrenia took longer to name font-colours.
Culturally biased diagnostic system. - Only explain proximal origins of symptoms. Not understood how genetics and childhood may impact metarepresentation or central control.
- Abnormal cognition may be due to genetic meaning schizophrenia is biological rather than cognitive.
