PMT

• Schizophrenia


  A mental disorder characterised by psychosis. Patients find it difficult to distinguish between reality and their own thoughts.
• Positive symptoms of schizophrenia


  • Hallucinations
  • Delusions
• Negative symptoms of schizophrenia

  • Speech poverty (alogia)
  • Avolition
• ICD-10/11 Classification System


  Used by World Health Organisation (WHO). Requires 2 or more negative symptoms for a diagnosis.
• DSM-V Classification System


  Used by American Psychiatric Association (APA). Requires one positive symptom for diagnosis.
• Reliability


  • Inter-rater reliability: extent that two clinicians will reach the same diagnosis
  • Test-retest reliability: whether the same diagnosis is reached for the same individual on two occasions by one clinician
• Historically, reliability has been low but recent studies suggest higher reliability. Osario et al. (2019) found inter-rater reliability of +.97 and +.92 for test-retest reliability.
• Validity


  The extent that a diagnosis represents something that is real and distinct from other disorders and whether the ICD or DSM measure what they claim to measure
• Cheniaux et al. (2009) found that when two psychiatrists assessed the same clients using both ICD and DSM that 68 were diagnosed with the ICD and only 39 under the DSM. So, depending on the system used, Schizophrenia may be over or under diagnosed.
• Factors affecting reliability and validity


  • Co-morbidity
  • Gender bias
  • Symptom overlap
  • Culture bias
• Co-morbidity


  The extent to which two (or more) conditions occur at the same time in a patient. Schizophrenia is often diagnosed alongside other conditions, e.g., 50% also have depression, 47% substance abuse and 23% OCD (Buckley et. al, 2009). This makes diagnosis and treatment difficult, and schizophrenia may not even be a distinct disorder.
• Gender bias


  More men are diagnosed than women but this could be because women have more social support and so function better (Cotton et. al., 2009). This leads to underdiagnosis and a lack of treatment for women.
• Symptom overlap


  Many symptoms of Schizophrenia are also symptoms of other disorders, for example, bipolar disorder. Therefore, it could be that they are not two separate conditions but different variations of the same condition.
• Culture bias


  Symptoms can be interpreted differently in different cultures. African-Caribbean British people are 9 times more likely to be diagnosed than White British people. The diagnostic system may be culturally-biased.
• Biological explanations for schizophrenia

  • Genetics
  • Neural correlates
• Genetic explanations


  • Family studies: If one family member has Schizophrenia then the chance of another member also being diagnosed with it increases as they become more genetically similar
  • Candidate genes: Schizophrenia appears to be polygenic in that a combination of different genes may cause it. It is believed that genes responsible for coding dopamine neurotransmitters are most likely to be involved
  • Mutation: Even if there is no family history of Schizophrenia, it could be caused by a mutated gene of a parent through radiation, viral infection or poisoning
• Evaluation of genetic explanations

  • Environment: The fact that the concordance rate for twins is not 100% means that Schizophrenia cannot be accounted for by genetics alone
  • Diagnostic criteria: Cardno et al (1999) used the 'Maudsley Twin Register' which uses strict diagnostic criteria and found a concordance rate of 26.5% for identical twins and 0% for fraternal twins. We cannot compare studies using different criteria
  • Adoption studies: Hiker et al. (2018) found a concordance rate of 33% for identical twins and 7% for fraternal twins even though they were adopted, suggesting a genetic basis
• Neural correlates of schizophrenia

  • Ventral striatum
  • Superior temporal gyrus and anterior cingulate gyrus
  • Dopamine hypothesis
• Dopamine hypothesis


  • Hyperdopaminergia = Excess levels of dopamine receptors in the pathway from the subcortex to the Broca's Area, causing speech poverty/auditory hallucinations
  • Hypodopaminergia = Low levels of dopamine in the prefrontal cortex causing problems with thinking and decision making (negative symptoms)
• Evaluation of neural correlates

  • Drug therapy: Antipsychotics reduce symptoms by reducing dopamine and amphetamines worsen symptoms as they increase dopamine. This gives evidence for the dopamine hypothesis
  • Glutamate: McCutcheon et al. (2020) found that schizophrenics have a deficiency in glutamate function, which could have a more important role in Schizophrenic symptoms
  • Correlations: Correlations with brain areas does not imply causation. Do they have abnormal activity due to the schizophrenia for instance? These studies cannot explain why these areas have higher or lower activity
• Psychological explanations for schizophrenia


  • Family dysfunction
  • Cognitive explanations
• Family dysfunction explanations


  • Schizophregenic mother: Fromm-Reichmann's (1948) psychodynamic explanation explains that a mother who is cold, rejecting and controlling can cause schizophrenia in her child
  • Double-bind theory: Children who receive contradictory messages from their parents are more likely to develop schizophrenia, as they fear doing the wrong thing but get mixed messages about what this is
  • Expressed emotion (EE): A high EE household contains 1) verbal criticism 2) hostility and 3) emotional overinvolvement. This can worsen schizophrenic symptoms and cause relapse
• Evaluation of family dysfunction explanations

  • Parent blaming: These theories are socially sensitive as they effectively blame the parent for the cause or relapse of their child's schizophrenia
  • Support for double bind: Berger (1965) found that schizophrenics reported a higher recall of double bind statements made by their mothers, than non-schizophrenics
  • Lack of evidence: The theories of schizophregenic mother and double bind have no systematic evidence to support them and are only based on informal assessments
• Cognitive explanations


  • Metarepresentation dysfunction: This is the inability to recognise that our own behaviours/thoughts are being carried out by ourselves rather than another person. This explains symptoms such as hallucinations and delusions
  • Central control dysfunction: This is the inability to suppress our automatic thoughts and the speech triggered by our unconscious processes. This explains symptoms like disorganised speech and thought
• Schizophrenics have more difficulty recognising that their own behaviours/thoughts are being carried out by themselves rather than another person
• Metarepresentation dysfunction


  The first type of dysfunctional thought processing, experienced as having difficulty in recognising that our own behaviours/thoughts are being carried out by ourselves rather than another person
• Central control dysfunction


  The second type of dysfunctional thought processing, the inability to suppress our automatic thoughts and the speech triggered by our own thoughts
• PET scans show under activity in the frontal lobe of the brain which is linked to self-monitoring, which schizophrenics have less control over
• Stirling et al. (2006) found schizophrenics took twice as long to complete the Stroop test suggesting impaired cognitive processing
• Diathesis-stress model


  States that an individual will develop schizophrenia if they have a biological disposition and an environmental trigger
• Meehl (1962) stated that the diathesis (vulnerability) was a schizogene and that anyone with this would be susceptible to stress and develop schizophrenia (especially if they have a schizophregenic mother)
• Now we understand that many genes could contribute to vulnerability and even childhood trauma could be the diathesis, such as child abuse. Stressors can also extend beyond the idea of parenting, for instance the use of cannabis could act as a stressor
• The diathesis-stress model could be deemed too simplistic as there are multiple biological and psychological causes of diathesis and stress
• Adopted Finnish children who had biological mothers with schizophrenia AND adoptive parents who were hostile, critical and had low empathy were more likely to develop the disorder (Tienari et al., 2004)
• Typical antipsychotics


  Created in the 1950s, taken orally, dosages start low and work up to around 400-800mg, known as dopamine antagonists as they reduce the levels of dopamine in the brain by blocking dopamine receptors
• Typical antipsychotics


  • Chlorpromazine, Pimozide
• Atypical antipsychotics


  Created in the 1970s, have less side effects than typical antipsychotics, can treat negative as well as positive symptoms by also acting on serotonin and glutamate receptors
• Atypical antipsychotics


  • Clozapine, Risperidone
• Meltzer (2012) found that clozapine is more effective than typical and other atypical antipsychotics, it reduced symptoms in 30-50% of patients who did not improve with typical antipsychotics
• We do not fully understand why these drugs work and recent research suggest that low levels rather than high levels of dopamine could cause schizophrenia and so they may not be the best treatment for all