Schizophrenia

• Schizophrenia


  A psychotic disorder marked by severely impaired thinking, emotions, and behaviours. Schizophrenic patients are typically unable to filter sensory stimuli and may have enhanced perceptions of sounds, colours, and other features of their environment
• Symptoms of schizophrenia


  • Positive symptoms
  • Negative symptoms
• Positive symptoms


  Enhance the typical experience of sufferers, and occur in addition to their normal experiences e.g. hallucinations and delusions
• Negative symptoms


  Take away from the typical experience of sufferers, and so represents a 'loss' of experience e.g. speech poverty and avolition
• Hallucinations


  A positive symptom of schizophrenia, which is characterised by a distorted view/perception of real stimuli or perceptions of stimuli which have no basis in reality
• Delusions


  A positive symptom of schizophrenia and are a set of beliefs with no basis in reality at all
• Speech poverty


  A negative symptom of schizophrenia which occurs when there is an abnormally low level of the frequency and quality of speech
• Derailment


  A type of speech poverty thought to be caused by dysfunctions in central control, where the sufferer cannot suppress the automatic associations that come with each new word or idea
• Avolition


  A negative symptom of schizophrenia, meaning the inability to cope with the normal pressures and motivations associated with everyday living and day-to-day tasks
• Classification systems for mental disorders

  • Diagnostic and Statistical Manual (DSM-V)
  • International Classification of Disease (ICD-10)
• Differences between DSM and ICD

  • Organisations that produce them
  • Number of symptoms and specificity of symptoms required for diagnosis
  • Recognition of different subtypes of schizophrenia
• Subtypes of schizophrenia


  • Positive schizophrenia
  • Mixed schizophrenia
• There is a significant co-morbidity (high frequency of diagnosis of two disorders together) between schizophrenia and other mental health disorders, such as OCD and post-traumatic stress disorder
• The high frequency of diagnosis of schizophrenia with other psychiatric disorders suggests that these two disorders may actually be the same, and so a more accurate and valid method of diagnosis would be to combine these two
• There may be gender bias in the diagnosis of schizophrenia, as suggested by the sudden increase in the number of male SZ diagnoses made after 1980s
• The current system of the diagnosis of schizophrenia does not account for gender differences in functioning, increasing the likelihood of inaccurate diagnoses
• There is also a problem of racial bias in the diagnosis of schizophrenia, as African Americans are far more likely to be diagnosed with SZ compared to patients belonging to Western cultures
• The phenomenon of hearing voices may be considered a desirable sign of increased spirituality and connectedness with ancestors in some cultures, but both classification systems would view this as a hallmark characteristic of schizophrenia
• Genetic basis of schizophrenia

  Schizophrenia runs in families, with higher concordance rates in genetically similar individuals
• There are no 100% concordance rates for schizophrenia in monozygotic twins, demonstrating that there are environmental influences acting on the development of schizophrenia
• Candidate genes for schizophrenia

  Genetic variations which marginally increase the risk of developing schizophrenia
• Schizophrenia is a polygenic disorder, meaning it has multiple contributing candidate genes
• Dopamine hypothesis


  The original hypothesis suggests that hyperdopaminergia (abnormally high dopamine levels) in the subcortex is responsible for schizophrenia, while the revised hypothesis suggests that hypodopaminergeria (abnormally low dopamine levels) in the cortex is more likely to be responsible

  
• The modern understanding is that both hyper- and hypodopaminergia in different areas of the brain contribute to the development of schizophrenia
• Hyperdopaminergia in Broca's area

  May be responsible for the positive symptom of auditory hallucinations
• Hypodopaminergia in the prefrontal cortex


  May be responsible for negative symptoms of schizophrenia such as speech poverty and avolition
• Neural correlates


  Specific patterns of cortical activity or neural structures which coincide with specific psychological symptoms, and so are assumed to contribute towards those symptoms
• Abnormally low levels of activation in the ventral striatum


  May be associated with the negative symptom of avolition
• Mis-identification of self-generated speech in patients with auditory verbal hallucinations

  Associated with functional abnormalities in the anterior cingulate and left temporal cortex
• The risk of having offspring with schizophrenia increased by over 1.3% if the father was over 50 years old, compared to if the father was under the age of 25
• The evidence for the dopamine hypothesis of schizophrenia can be best described as 'mixed'
• Antipsychotics


  Act as dopamine antagonists and so reduce dopamine activity by binding to complementary receptors on the post-synaptic membrane
• Antipsychotics alleviated the symptoms of schizophrenia, suggesting that dopamine has a key role in its development, in line with the predictions of the dopamine hypothesis
• Some researchers have criticised the dopamine hypothesis and biological explanations of schizophrenia as emphasising the role of dopamine too far
• The neurotransmitters glutamate and serotonin may also play a key role in schizophrenia, as evidenced by the antipsychotic Clozapine acting upon both of these substances and being more effective than other atypical antipsychotics in reducing schizophrenia symptoms
• Neural correlates as a means of explaining schizophrenia

  • Correlational evidence does not take into account the 'third variable problem', whereby a third unstudied factor could be affecting both outcomes
  • Correlational research cannot be used to reliably demonstrate a 'cause and effect' relationship between two variables
• Psychological explanations for schizophrenia

  Suggest that the development of schizophrenia is due to abnormal family communication styles, mixed messages, and the stress caused by high levels of expressed emotion
• Schizophrenogenic mother


  Characterised as being cold and rejecting, leading to a tense family climate lacking in honesty, which develops paranoia and anxiety in the child
• Double-bind theory


  Within a family, the child receives mixed messages from both parents about what is right or wrong, leading to the child seeing the world as unfair and confusing
• Expressed emotion


  The level and type of emotion shown towards the patient by their carer, which is often a significant source of stress for the patient