Psychology - Schizophrenia

• What does it mean by ‘classification of mental disorder’?

  The process of organising symptoms into categories based on which symptoms frequently cluster together
• How much of the world is affected by schizophrenia? (A01)

  About 1% of the world is affected by this serious mental disorder. It is more commonly diagnosed in men, city-dwellers and lower socio-economic groups. The prevalence of schizophrenia is 40% higher in males than females. It tends to have an onset from adolescence, around mid 20s.
• How do the DSM and ICD differ in their classification of schizophrenia?

  Answer:

  
• What does the diagnosis of a mental disorder involve?

  It is a process of a deciding if someone has a disorder, by using diagnostic criteria and identifying whether a patients has symptoms.
• What does it mean by ‘positive symptoms’ of schizophrenia?

  Atypical symptoms which are added to behaviour
• What is schizophrenia?

  A severe mental disorder where contact with reality and insight are impaired, an example of psychosis
• What does it mean by ‘negative symptoms’ of schizophrenia?

  Atypical symptoms which take away from behaviour
• State examples of positive symptoms of schizophrenia

  Hallucinations and delusions
• State examples of negative symptoms of schizophrenia

  Avolition and speech poverty (alogia)
• Describe hallucinations as a positive symptom of schizophrenia

  • They are sensory experiences that either have no basis in reality or are distorted perceptions of things that are there
  • ‘Perception like experiences that occur without an external stimulus’
  • Visual hallucinations, i.e., seeing things
  • Auditory hallucinations i.e., hearing voices
• Describe delusions as a positive symptom of schizophrenia

  • They involve beliefs that have no basis in reality, for example, a person believes that they are someone else or that they are the victim of a conspiracy
  • ‘Fixed beliefs that are not amenable to change in light of conflicting evidence’
  • Delusions of persecution/paranoid delusions: others are plotting against you
  • Delusions of grandeur: you are someone important
  • Delusions of reference: events have a particular significant to you
• Describe speech poverty (alogia) as a negative symptom of schizophrenia

  • It involves reduces frequency and quality of speech
  • ’Diminished speech output’
  • Quality: reduced vocabulary and grammatical compelxity
  • Frequency: say less overall and in incomplete sentences
• Describe avolition as a negative symptom of schizophrenia

  • It involves loss of motivation to carry out tasks and results in lowered activity levels
  • ’A decrease in motivated self-initiated purposeful activity’
  • For example, a reduction of taking part in activities that they would normally do voluntarily and for a reason
  • E.g work, relationships, hobbies
• Describe the term ‘genetics’

  Genes consist of DNA strands. DNA produces ‘instructions’ for general physical features of an organism (such as eye colour, height) and also specific physical features (such as neurotransmitter levels and size of brain structures). These may impact on psychological features (such as intelligence and mental disorder). Genes are transmitted from parents to offspring, i.e. inherited
• Describe the process of how psychologists came to the conclusion that schizophrenia has a genetic basis

  • In the 1960s it was thought that schizophrenia was entirely genetic
  • Family studies found that schizophrenia ran in families to some extent
  • In the 1980s it was suggested that they could be a gene for schizophrenia
  • It is now accepted that schizophrenia is polygenic i.e. involves multiple genes
• What is heritability?

  It refers to the extent to which a condition or trait has been passed on generationally through families via genes
• Describe family studies and schizophrenia

  • Family studies have confirmed that risk of schizophrenia increases in line with genetic similarity to a relative with the disorder
  • For examples, Gottesman (1991) carried out a meta-analysis of family studies
  • He found that MZ twins have a 48% risk of developing schizophrenia and DZ twins a 17% risk rate
  • This evidence shows that the higher the degree of genetic relativeness, the higher the risk of getting schizophrenia
• Describe candidate genes/polygenic nature of schizophrenia

  • Early research in this area looked for a single genetic variation and that one faulty gene could explain schizophrenia
  • However, it appears that several genes are involved which means schizophrenia is polygenic
  • The combined effect of several genes increases the risk of developing the illness
  • In particular, genes that code for neurotransmitters like dopamine
  • The genes which may increase a person’s risk are known as candidate genes
• Describe research carried out about the polygenic model and candidate genes

  • Ripke et al. (2014) carried out a meta-analysis on genome-wide studies of schizophrenia
  • The genetic make-up of 37,000 people with a diagnosis of schizophrenia was compared to that of 113,000 controls. 108 separate genetic variation were associated with slightly increase risk of schizophrenia
  • Since different studies have identified different candidate genes, schizophrenia appears to be aetiologically heterogenous (i.e different combinations of factors, including genetic variation, which can lead to the condition)
• Describe the role of mutation in developing schizophrenia

  • Even if there is an absence of schizophrenia in a person’s family history they can still develop the illness
  • This is due to mutation in parental DNA due to things like radiation, poison or viral infection
  • Evidence supports this by showing positive correlations between paternal age and risk of schizophrenia
  • This increase from around 0.7% with fathers under 25 to over 2% in fathers over 50 (Brown et al. 2002)
• Why is the diathesis-stress model better than the genetic theory or a purely environmental explanation?

  • Genes cannot be a complete explanation or the concordance rates for MZ and DZ twins would be much higher
  • The environment cannot be a complete explanation either or rates of SZ would be higher, as stressors are common
• What are monozygotic twins?

  • Identical twins that share 100% of genes
  • Same age, raised together, so very similar environments
• Describe dizygotic twins

  • Non-identical twins
  • Share 50% of DNA
  • Same age, raised together, so very similar environments
• What are some strengths of twin studies?

  • They control for the environment
  • This enhances scientific credibility
• What are some limitations of twin studies?

  • MZ are treated more similarly than DZ
  • Twin studies may exaggerate influence of genetic
  • Reduces scientific credibility of genetic theory