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Diagnosis and classification of schizophrenia

Schizophrenia doesn’t have a single defining characteristic. There are many symptoms some of which appear to be unrelated. For diagnosis according to the: DSM-5 1 positive symptom must be present, IDC-10 - 2+ negative symptoms are sufficient for diagnosis.


  • Positive symptoms - these are additional experiences beyond those of ordinary existence.
    • Hallucinations, sensory experiences that have no basis in reality or distorted perceptions. e.g. hearing voices.
    • Delusions/paranoia are irrational beliefs - make schizophrenics behave in ways that may seem bizarre to others. e.g. the victim of a conspiracy.
  • Negative symptoms - the loss of usual abilities and experiences.
    • Avolition, difficulty to begin or keep up with goal-directed activity.
    • Speech poverty, a reduction in the amount and quality of speech. DSM emphasises speech disorganization.
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Diagnosis and classification of schizophrenia - Ev

P - One limitation of a diagnosis of schizophrenia is low reliability.

E - Cheniaux et al. had two psychiatrists independently diagnose 100 patients using both DSM and ICD. Inter-rater reliability was poor, with one diagnosed 13/24 according to DSM. the other diagnosed 24/44 with the ICD.

P - Another limitation in the diagnosis of schizophrenia is validity.

E - Cheniaux et al.'s study show schizophrenia is more to be diagnosed ICD but less in DSM.

E - To assess the validity of a diagnosis is criterion validity; Do different assessment systems arrive at the same diagnosis for the same patient?

P - A further limitation in the diagnosis of schizophrenia is symptom overlap.

E - Schizophrenia and bipolar disorder involve positive symptoms like delusions and negative symptoms like avolition.

E -This again calls into question the validity of both the classification and diagnosis of schizophrenia.

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Biological explanations for schizophrenia

  • There's a strong relationship between genetic similarity of family members and the likelihood of both developing schizophrenia. MZ twins share 100% of genes, 50% with siblings or parent and so on.
  • Schizophrenia is polygenic. Each gene gives a small increased risk of schizophrenia. Different combinations can lead to schizophrenia - aetiologically heterogeneous.
  • Dopamine is important in the functioning of several brain systems that may be linked to the symptoms of schizophrenia.
  • Hyperdopaminergia - high levels of activity of DA in the sub-cortex associated with hallucinations and speech poverty.
  • Hypodopaminergia in the cortex - low DA activity in the brain’s prefrontal cortex (decision making).
  • Neural correlates of schizophrenia are measurements of the structure/function of the brain correlate with experience.
  • The ventral striatum is involved in anticipation of reward, related to motivation. Avolition in schizophrenia may be explained by low activities there. Juckel et al. measured activity levels in the ventral striatum in schizophrenia, found lower activity levels than those in controls.
  • Allen et al. brain scanned patients experiencing auditory hallucinations and compared them to a control group. Lower activation levels in the superior temporal gyrus and anterior cingulate gyrus were found in the hallucination group.
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Biological explanations for schizophrenia - Evalua

P - One strength is strong evidence for genetic vulnerability to schizophrenia.

E -Tienari et al. show children of schizophrenia sufferers are still at high risk if adopted in families with no history of schizophrenia.

P - There is mixed evidence for the dopamine hypothesis.

E - Curran et al. found Dopamine agonists dopamine levels and can produce schizophrenia-like symptoms in non-suffered. Antipsychotic drugs that lower dopamine can reduce symptoms.

P - Another limitation is the correlation-causation problem.

E - It is unclear whether unusual activity in the brain causes the symptoms or whether there are other explanations.

E - A negative correlation may suggest that low activity in the ventral striatum causes avolition, But it could be that avolition means less information passes through the striatum resulting in low activity.

L - The existence of neural correlates in schizophrenia, therefore, tells us relatively little.

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Psychological Explanations for Schizophrenia

Family dysfunction • According to Fromm-Reichmann the schizophrenogenic mother is cold, rejecting and controlling, and tends to create a family climate characterised by tension and secrecy. Leading to distrust later developing paranoid delusions and ultimately schizophrenia.

Double – bind theory, conflicting family communication • Bateson et al. - the child regularly are trapped in situations they fear doing the wrong thing but receive mixed messages. They cannot express the feelings of the unfairness of the situation. Leaving them with a confused understanding and this is reflected in symptoms like paranoid delusions.

Expressed emotions - the level particularly negative emotions, expressed at a patient by carers. • EE contains several elements: Verberal criticism, hostility towards the patients, emotional over-involvement in their life. High levels of EE causes stress, relapse explanation.

Cognitive explanations • Lower level of information processing in some areas of the brain suggests cognition is impaired. • Dysfunction in metarepresentation would disrupt our ability by ourselves rather than someone else. This would explain auditory hallucinations and delusions like thought insertion. • Dysfunction of central control is the cognitive inability to suppress automatic responses while performing deliberate actions. Sufferers experience derailment of thought and speech because each word triggers associations they cannot suppress automatic responses.

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Psychological Explanations for Schizophrenia - Eva

P - There is research support for family dysfunction as a risk factor.

E - Read et al. reviewed studies of child abuse and schizophrenia. Found 69% of adult women in-patients had physical/sexual abuse in childhood. For men 59%. 

E  - There is thus a large body of evidence linking family dysfunction to schizophrenia.

E - Weakness in evidence – information about childhood experiences was gathered after the development of symptoms. 

L - The schizophrenia may have distorted patients’ recall of childhood experiences which mean a serious lack of validity, thus not entirely trustworthy evidence supports the theory.

P - There is strong evidence for dysfunctional information processing.

E - Stirling et al. compared patients with non-patient controls of cognitive tasks, plus the Stroop test. With the central control dysfunction, patients took over twice as long than the control.

L - Cognition theories can explain the proximal causes of the schizophrenia.

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Biological Therapies for Schizophrenia: Drug Thera

Typical antipsychotics e.g. Chlorpromazine, since the 50s.

  • They work by as an antagonist in the dopamine hypothesis, reduce the action of a neurotransmitter, so blocking dopamine receptors in the synapses. Therefore, reducing the action of dopamine.
  • Initially, dopamine levels build-up, but then its production is reduced. This normalises neurotransmission, which in turn reduces symptoms like hallucinations.
  • Chlorpromazine has a sedation effect to calm patients when they're first attempted to hospital.

Atypical antipsychotics e.g. Clozapine 70s and Risperidone since the 90s.

  • The aim - improve drugs’ effectiveness in suppressing psychoses and minimise side effects.
  • Clozapine binds to dopamine receptors and it acts on serotonin and glutamate receptors.
  • Helps improve mood and reduce depression and anxiety in patients, and that it may improve cognition. Mood-enhancing effects can help patients who are considered high-risk of suicide.
  • Risperidone was developed because of Clozapine's fetal side effects.
  • Risperidone binds more strongly to dopamine receptors than Clozapine and thus effective in a smaller dosage. Has fewer side effects.
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Biological Therapies for Schizophrenia: Drug Thera

P - One strength is the evidence for effectiveness of antipsychotics.

E - Thornley et al. reviewed studies comparing effects of Chlorpromazine to control conditions with a placebo. Data from three trials, showed a lower relapse rate when Chlorpromazine was taken. Also, there’s support for the benefits of atypical antipsychotics.

P - One limitation of antipsychotics drugs are the side effects.

E - Typical drugs can cause – dizziness, agitation, sleepiness, stiff-jaw, weight gain, and itchy skin.

E - And so, patients may stop taking the drugs to stop the side effects thus relapsing or worse.

P - Another limitation is the theoretical objection to the use of antipsychotic drugs.

E - There is evidence that the original dopamine hypothesis is not a complete explanation of schizophrenia.

E - Dopamine levels in other areas of the brain are too low rather than too high. If this is true, then it’s not clear how antipsychotics, dopamine antagonists, can help with schizophrenia.

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Psychological therapies for Schizophrenia

Cognitive behavioural therapy (CTB) - help patients identify and change irrational thoughts.

  • This involves a debate of how likely the patient’s beliefs are to be true, and a possibility of less threatening possible.
  • Patients can be helped to make sense of how their delusions and hallucinations affect their feelings and behaviour - offering psychological explanations of the reality of hallucinations and delusions can help reduce this anxiety.

Family therapy to improve the quality of commutations and interaction among family members.

  • Family therapy concerned with reducing stress within the family that may add to relapse risk.
  • Pharaoh et al. identified a range for strategies to reduce relapse risk and hospital readmission: Reduce stress of caring for a schizophrenic relative, improving the ability of the family to anticipate and solve problems, reduce anger guilt in family members and Improving beliefs about and behaviour towards schizophrenia.

Token economies are a reward system based on operant and classical conditioning.

  • Token, secondary reinforcers, are given to patients who carry out desirable behaviour. Value is learned by association.
  • Tokens are traded for rewards which reinforces the desirable behaviour is reduces delay reward effect.
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Psychological therapies for Schizophrenia - Evalua

P - One strength of psychological therapies is research shows some benefits.

E - Pharoah et al. reviewed the evidence for the effectiveness of family therapy. They concluded there is moderate evidence to show family therapy significantly reduced hospital readmission.

E - And improved the quality of life for patients and their families.

E - However, the results of different studies were inconsistent and had problems with the quality of some evidence. The evidence base for family therapy is weak.

L - Overall there’s little support for the effectiveness of psychological treatments and schizophrenia remains harder to treat.

P - Treatments improve quality of life but don’t cure.

E - CBT helps patients make sense and challenge some of their symptoms. Family therapy reduces the stress of living with schizophrenia. Token economies help patients’ behaviour become socially acceptable so they can return to society.

E - They improve quality of life but don't cure. Biological treatments don’t cure but reduce some symptoms.

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Interactionist Approach to Schizophrenia

The diathesis-stress model says both a vulnerability to schizophrenia and a stress-trigger are needed for the development of the condition. Meehl’s model - the diathesis was entirely genetic, the result of a single ‘schizogene’:

  • Meehl – if a person doesn’t have the schizogene then no amount of stress would lead to schizophrenia. But it's they are vulnerable to the effect chronic stress from e.g. schizophrenogenic mother.
  • Modern understanding of diathesis has changed, its clear many genes each seem to faintly increase genetic vulnerability. There is no single ‘schizogene’ – Ripke et al.
  • Psychological trauma could become the diathesis rather than the stressor.
  • Cannabis is a stressor because it increases the risk of schizophrenia by up to 7x according to dose.

Treatment according to the interactionist approach

  • Turkington et al. suggested its possible to believe in biological causes of schizophrenia and still practice CBT for symptoms.
  • However, this required adopting an interactionist model, so in Britain, it's increasingly standard practice to treat patients with a combination of antipsychotic drugs and CBT.
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Interactionist Approach to Schizophrenia - Evaluat

P - One strength is support for the dual role of vulnerability and stress.

E - Tienari at al. investigated the combination of genetic vulnerability and parenting style (the trigger). The adoptive parents were judged for child-rearing style, and rates of schizophrenia were related to a control group.

E - The child-rearing style with high levels of criticism and conflict and love levels of empathy was involved in the development of schizophrenia but only for children with a genetic risk.

L - Suggesting both genetic vulnerability and family-related stress the importance of adopting an interactionist approach to schizophrenia.

P - Another strength is the usefulness of the interactionist approach in treatment.

E - Tarrier et al. study patients were randomly put into a medication + CBT group, medication + supportive counseling or control group. Patients in the two mixed groups showed lower symptoms levels than those in the control group (medication only).

E - Studies like this show the practical advantage to an interactionist approach with superior treatment outcomes.

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