Aetiologies of schizophrenia

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  • Created by: gracepxx
  • Created on: 20-05-16 17:32

P1 - Intro

Schizopphrenia is characterised by a disruption of cognition and emotion, effecting a person's language, thought and sense of self

Some symptoms - delusion, experience of control, hallucinations, affective flattening  and avolition

Two of the main ways schizophrenia said to be caused - psychiological and psychological

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P2 - Physiological - Genetic - Family studies

 Family studies have established that schizophrenia is more common among genetic relatives of a person with schizophrenia

Closer the degree of genetic relatedness, the greater the risk

 Varma et al (1997) looked at the first degree relatives (FDRs) of about 1000 schizophrenics and 1000 controls – psychiatric illness was found in 16% of the FDRs of schizophrenics compared with 7% of the controls

 However, many researchers now accept that family concordance for schizophrenia may be more to do with common rearing patterns or other factors rather than heredity

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P3 - Physiological - Genetic - Twin studies

Twin studies also used – if MZ twins who share 100% of genes are more concordant than DZ twins who only share 50% it suggests that the greater similarity is due to genetic factors

Rosenthal (1936) studied quadruplets - all identical and all developed schizophrenia suggesting genetic cause - however, terrible upbringing could contribute to development of disord

 Alternative explanation for higher MZ rates – Joseph (2004) - MZ twins are treated more similarly, encounter more similar environments and experience more identity confusion than DZ twins – differences in concordance rates between MZ and DZ twins reflect nothing more than the environmental differences that distinguish the two types of twin

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P4 - Physiological - Genetic - Adoption studies

Studies of genetic relatives fail to disentangle the effects of shared genes and shared environment since relatives live together

 One alternative is to compare adopted children with and without biological parents diagnosed with schizophrenia

Tienari et al (2000) studied 164 adoptees whose biological mothers had been diagnosed with schizophrenia

Found 11 also received a diagnosis of schizophrenia, compared to just 4 of the 197 control adoptees born to non-schizophrenic parents 

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P5 - Physiological - Dopamine hypothesis

States that messages from neurons that transmit dopamine fire too easily or too often – leads to symptoms of schizophrenia

Schizophrenics thought to have abnormally high numbers of D2 receptors on receiving neurons, resulting in more dopamine binding and therefore more neurons firing

Dopamine neurons play a key role in guiding attention, so disturbances in this process may well lead to the problems of attention, perception and thought with schizophrenics

Drug effects – drugs that are known to increase levels of dopamine have also been found to create the characteristic hallucinations and delusions of a schizophrenic episode – includes recreational drugs and the drug L-dopa used for people with Parkinson’s who typically have low levels of dopamine

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P6 - Physiological - Brain Ventricles

Brain ventricles – research evidence to support the role of enlarged ventricles is far from consistent

Meta-analysis of over 90 brain scans revealed a substantial overlap between the schizophrenic and control populations in terms of ventricle size

 Possible explanation for why some schizophrenics have enlarged ventricles may be due to use of antipsychotic medication

Lyon et al (1981) - as dose of medication increased, the density of brain tissue increased, leading to enlarged ventricles

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P7 - Psychological - Psychodynamic

Freud (1924) believed that schizophrenia was the result of 2 processes - 1) Regression to a pre-ego stage 2) Attempts to re-establish ego control

Harsh experiences such as having uncaring parents leads to regression as an ego defence

Schizophrenia therefore seen by Freud as an infantile state with symptoms such as delusions reflecting this primitive condition and other symptoms such as auditory hallucinations reflecting a person's attempt to reestablish ego control

No research evidence to support Freud’s ideas, except insofar as subsequent psychoanalysts have claimed, like Freud, that disordered family patterns are the cause of the disorder

Fromm-Reichmann (1948) described “schizoprenogenic” mothers of families who were rejecting, overprotective and dominant, and act as important contributory influences in the development of schizophrenia.

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P8 - Psychological - Cognitive

Biological factors cause the initial sensory experiences of schizophrenia, but further features of the disorder appear as individuals attempt to understand those experiences

When sufferers first experience voices and other worrying sensory experiences, they turn to others to confirm the validity of what they are experiencing

Other people fail to confirm reality of experiences so the schizophrenic comes to believe that the others must be hiding the truth

 Develop delusional beliefs that they are being manipulated and persecuted by others

Evidence of a physical basis for the cognitive deficits associated with the disorder – Meyer-Lindenberg et al (2002) found link between excess dopamine in pre-frontal cortex and working memory

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P9 - Psychological - Life events

Major factor that has been associated with higher levels of schizophrenic episodes is occurrence of stressful life events

These are specific stressors, such as the death of a relative or the breakup of a relationship.

Brown and Birley (1968) studied people who had experienced schizophrenia – if they had a subsequent attack it was found they recorded twice as many stressful life events compared with a healthy control group

In any case, evidence that does suggest link between life events and the onset of schizophrenia is only correlational – could be that the beginnings of the disorder were the cause of the major life events – furthermore, life events after onset (lose job, divorce) may be a consequence rather than cause of mental illness

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P10 - Psychological - Double bind theory

Bateson et al (1956) - children who frequently receive contradictory messages from their parents are more likely to develop schizophrenia

E.g, if mother tells son she loves him yet turn her head in disgust, child receives two contradictory messages about relationship - child's ability to respond to mother is incapacitated due to contradictions

Interactions prevent the development of a coherent construction of reality, and in the long run, this manifests itself as schizophrenic symptoms

These ideas echoed in work of R.D Laing who argued that what we call schizophrenia is actually a reasonable response to an insane world

Some evidence to support account of how family relationships may lead to schizophrenia – Berger (1965) found that schizophrenics reported a higher recall of double bind statements by their mothers than non-schizophrenics – however, evidence may not be reliable as recall could be affected by their illness

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