Schizophrenia

Schizophrenia is a sever mental disorder characterised by a breakdown of thought and poor emotional response.

History

  • Hippocrates introduced the idea of schizophrenia as a mental 'dis-ease', putting it on par with a physical disease, and not something to be treated as moral degenerates
  • Kraepelin (1899) popularised studies and categorisations of illnesses such as dementia praecox
  • Eugen Bleuler (1908) first proposed the term 'schizophrenia' (schizo = split, phrene = mind). He referred to a split between emotion and cognition, not a split in personality.

Symptoms

SZ is a psychotic disorder; it's rare to diagnose SZ without psychotic symptoms. However psychosis does not imply SZ (could imply substance abuse or Bipolar Disorder (type 1)).

Positive symptoms are abnormal by existing, negative symptoms are abnormal because something is lacking.

Positive Symptoms

  • Hallucinations
    • Present in ~70%
    • Mainly auditory, can be others
    • Typically critical/abusive
    • Comment on person's actions, often multiple voices
  • Delusions
    • Present in >80%
    • Paranoid delusions
    • Delusions of grandeur
    • Delusions of reference
  • Disorganisation (of thought and behaviour)
    • Disconnected/incomprehensible thought/speech
    • Bizarre behaviour
    • Formal thought disorder; loose associations, tangential thinking, wernicke's type speech
    • Inappropriate affect
    • Bizarre dress

Negative Symptoms

First Rank Symptoms

Kurt Schneider suggested there were First Rank Symptoms (FRS) that were most characteristic of SZ. It turns out they are not unique to SZ, but are more common than in other psychotic disorders.

  • Audible thoughts
  • Hearing arguing voices
  • Commentator voices
  • Delusions of reference
  • Delusions of control
  • Thought insertion/withdrawal/Broadcast

Causes

All symptoms reflect confusion between self-generated and externally-generated thoughts and actions (Feinberg, 1978; Frith, 1992).

Corollary Discharge Theory

Corollary Discharges (also known as Efference Copies) predict and suppress sensory consequences of self-generated actions, enabling us to distinguish between internally/externally caused sensations.

There is evidence for the CD theory, in that SZ patients fail to predict and suppress self-generated sounds.

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Genetic Factors

SZ is highly heritable (Identical twins have a 48% chance of developing schizophrenia, for instance), but there is no single gene for it, rather lots of risk genes with a compounding effect.

Environmental

Family history is the greatest risk factor, but there are many environmental factors that play a role, common ones being:

  • Infections
  • Place/time of birth
  • Obstetric complications
  • Prenatal bereavement
  • Drugs
    • Drugs increase the risk of developing SZ (amphetamine increases 10x)

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Neurophysiological

There is much evidence that SZ is linked with abnormalities in brain structure and function. See Thompson et al, 2001, below:

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Dopamine

Dopamine and SZ are linked closely; all antipsychotic drugs block dopamine. For more information read dopamine the dopamine page.

The CD theory and the dopamine theory are perhaps linked through their connections with the motor system; loss of dopamine causes motor impairment, which perhaps impairs CD. (Disclaimer: entirely speculation).

Treatments

  • Biological; Antipsychotics
    • Also known as neuroleptics, these are the most effective treatment
    • Chlorpromazine (Thorazine) - France, 1951, Anaesthetic
      • SZ impact discovered 1952. Became first of 'typical' antipsychotics - Dopamine antagonists.
    • CLozapine - 1970s. First of 'atypical' antipsychotics
      • Dopamine antagonist, serotonin agonist
      • More effective against negative symptoms, less sever side effects
  • Psychological; Cognitive-Behavioural Therapy
    • Up to 40% of patients show residual symptoms after pharamcotherapy; psychotherapy is an effective adjunct to this.
    • Aims to minimise distress caused by symptoms and teach coping skills (rather than resolving symptoms)
      • E.g. teaches patients to be less compliant to command hallucinations. See Figure below for more information (Trower et al, 2004)
  • Transcranial Magnetic Stimulation
    • Inducing a weak electric current polarise/depolarises neurons; causes cells reorganisation
    • Preliminary evidence that it can alleviate auditory hallucinations and negative symptoms.

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Prevalence

  • 0.7% of the population
  • 150-200 thousand Australians
  • Similar prevalence across cultures
  • Approximately equal gender distribution
  • Typically lifelong, occurring around 18-30 years

Costs

  • Suicide rate more than 10x average (Large, 2010)
  • Financial cost >$1.85 billion AUD
  • 11% of homeless people have SZ
  • One of the worst diseases there is