Schizophrenia

• Schizophernia is broadly characterised by psychosis (impaired contact with reality) but many other symptoms

  affects 1% of population at some point in their lives

  onset usually occurs in adolescence and early childhood
• diagnosing schizophrenia?

  does not have one pathogonomic symptom (characteristic indicative of a particular disease; better thought of as a cluster of symptoms

  means that not all symptoms will be experienced by all patients
• What are positive symptoms?

  atypical symptoms which are experienced in addition to normal experiences; something Is added to the person
• what are negative symptoms?

  atypical symptoms which are experienced as a loss of normal experience

  something is taken away from the person
• positive symptoms of schizophrenia: hallucinations delusions disorganised speech and disorganised behaviour
• negative symptoms of schizophrenia; avolition, affective flattening, alogia
• hallucinations are unreal perceptions of the environment; auditory, visual, olfactory and tactile
• delusions are bizarre beliefs that seem real but are not; paranoia, experiences of control and grandiose
• disorganised behaviour can vary from being childlike and silly to aggressive and violent; excessive movements, not responding to instructions, freezing in place- unprovoked agitation
• disorganised speech is where a person may go on lots of tangents and make little sense in sentences; manifestation of highly disorganised cognition
• avolition is the reduction in goal orientated behaviour or motivation to begin a task; poor hygiene, lack of perseverance and lack of energy
• affective flattening is lack of emotional expression; person may not show contextually appropriate emotions

  less use of emotionally salient language when verbally expressing emotion
• Problems with underdiagnosis?


  people with schizophrenia wont get the treatment they need and there are societal issues; those with untreated schizophrenia are less likely to work which has economical impacts
• problems with overdiagnosis?

  unnecessary treatments like antipsychotics are economic burdens; people who do need treatment may go without

  there are side effects with unnecessary intake
• outline cheniaux study 


  2 psychiatrists diagnose 100 case studies using DSM and ICD

  A)

  B)

  
• comorbidity is where 2 or more disorders are frequently diagnosed in the same person
• validity when classifying and diagnosing schizophrenia?

  • are we diagnosing schizophrenia when we should be
  • is schizophrenia distinct from other disorders
• symptom overlaps where one symptom is found in multiple disorders?


  in depression, bipolar and schizophrenia, depressed mood and avolition are occuring symptoms

  in both schizophrenia and bipolar, mania, hallucinations, delusions and inflated sense of self are all occuring symptoms

  alogia is specific to schizophrenia (not a core symptom)
• hard to tell the difference between bipolar and schizophrenia because too many symptoms overlap
• — loreng and Powell gender bias in diagnosis?

  290 psychiatrists to diagnose 2 case studies; males= 56% female= 20%; if female clinician then gender bias disappears

  shows that male psychiatrists don’t diagnose females with schizophrenia when they show the same symptoms as makes so they are either over diagnosing males or under diagnosing females; the latter is more likely because they see females as more hysterical
• issues with reliability of classifying and diagnosing schizophrenia?

  — do different psychiatrists give the same diagnosis to the same set of symptoms

  — is there an agreement between cultures
• cheniaux (200) in terms of reliability?

  comparing psychiatrists 1 and 2; psych 1 always double diagnosis regardless of what tool they use(DSM or ICD)

  psychiatrist 1 diagnosis of schizophrenia at double rate regardless of criteria’s which shows clinicians are unreliable
• outline Copelands study and findings into reliability of diagnosing schizophrenia across cultures?

  — have 1 case study to 134 US psychiatrists and 194 british psychiatrists

  — found 69% of US diagnosed and only 2% of British diagnosed (x35)

  — cultural difference could be due to different health cares; in the us healthcare is private whereas britain is free so they will be less likely to diagnose as it puts a strain on the NHS ; private doctors in the US more likely to diagnose to gain more money for resources
• what are the three study’s that biologically explain the genetics behind schizophrenia?

  1 twin studies (gottesman)

  2 adoption studies (tienari)

  3 polygenic (Ripke)
• outline Gottesmans study and findings?

  — there is a genetic basis for schizophrenia

  1 the more dna you share with a schizophrenic, the greater the concordance rate/ risk of developing schizophrenia

  2 MZ twins = 48% concordance rate. DZ twins = 17% concordance rate; shows genetic link because doubles in percent however shows that it can’t be entirely genetic otherwise concordance rate would be 100% and 50%
• Gottesman concordance rates

  
• what’s an issue with twin studies?

  the equal environment assumption may be incorrect;

  • DZ twins may not be the same gender
  • DZ twins may look different (halo effect; treated differently based on looks)
• outline Tienaris study and findings?

  — large scale Finnish adoption study with 303 adoptees

  high risk = biological mother had schizophrenia

  low risk = biological mother did not have schizophrenia

  family problems were measured across three domains and averaged (adoptive family)

  found;

  having family dysfunction in the adoptive house only increases schizophrenia risk for the high risk group (diathesis stress model)
• what is a candidate gene?

  a specific gene thought to be involved in the development of a trait
• outline Ripkes study and findings ?


  schizophrenia is polygenic; analysed genomic wide studies; 37000 patients were compared to 113000 controls and found 108 candidate genes eg; PCM1
• What is a neural explanation for schizophrenia?

  the dopamine hypothesis
• the dopamine hypothesis argues that schizophrenia is caused by both high and low levels of dopamine
• what is dopamine?

  — excitatory neurotransmitter

  — reward/ learning; anticipation of reward

  — controls movement
• hyperdopaminergia in the sub cortex leads to high levels of dopamine
• hypodopaminergia in the cortex leads to low levels of dopamine
• How does hyperdopaminergia in the sub cortex lead to positive symptoms in schizophrenia?

  — excessive dopamine may alter subcortical auditory neurons leading to hallucinations
• how does hypodopaminergia in the cortex cause negative symptoms of schizophrenia?


  — low levels of dopamine in the prefrontal cortex (responsible for thinking and decision making) may be responsible for symptoms such as avolition

  — reduced dopamine in regions such as broacs area may be involved in speech poverty (alogia)
• research evidence into the effects of drugs?

  1 amphetamines act as dopamine agonists and have been found to worsen psychosis in schizophrenia patients and induce schizophrenia like symptoms in healthy controls (Curren et al)

  2 anti psychotics which reduce dopamine activity have been found to relieve psychosis (Tauscher et al)

  — taken together these studies suggest that excessive dopamine does play a role in positive symptoms of schizophrenia