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Explanations for (causes of schizophrenia) (Biological (Dopamine…
Explanations for (causes of schizophrenia)
Biological
Genetic
Certain genes or variations of genes have something to do with schizophrenia
four types of evidence
Three types of studies
Family studies
Look at people (children) with schizophrenia and then look at their parents/siblings (blood relatives)
Need to look for concordance rate between person w/ schizophrenia and other relatives
Fairly high concordance rates for family members
46% percent concordance w/ both parents and child having schizophrenia
1 parent = 13%
Sibling = 9%
The more closely related they are, the higher the concordance rate is
Gurling et al.
family studies + gene mapping
found taht PCM1 gene made people more likely to get schizophrenia
Criticisms
Concordance may be because of experiencing the same environment instead of genetics
Twin studies
Two types of twins
Monozygotic
Dyzygotic
Will have sample of both type of twin
Look for concordance rate between them
If Genetics plays a part in schizophrenia, concordance rate in MZs should be higher than DZs
should also expect concordance rate in MZs to be 100%
Joseph
Metaanalysis for all schizophrenia twin studies up to 2001
concordance rate for MZs 40.4% and DZs 7.4%
Concordance rate for MZs is very rarely 100%
More recent studies used "blind" diagnoses where psychologists did not know whether they were MZ or DZ
lower concordance rate for MZs
still support genetic position because MZ concordance higher
MZs treated very similarly and therefore have more similar environment
Adoption studies
looking for concordance rate in adopted children w/ parents (sometimes twins)
Eliminates confounding variable of environmental influence
Tienari
164 adoptees whose mothers had schizophrenia
11 had diagnosis of schizophrenia
only 4 of control group (197) had schizophrenia
Adoptees may be selectively placed
adoptive parents are told genetic background of child + schizophrenics more prepared to adopt this child creating environmental factors.
Adoption studies evidence are not convincing because sample sizes are usually very small
Difficult to generalise from (low levels of representativeness)
Gene mapping offers possibility of developing test to identify high risk individuals
Analysis of DNA of 36,989 schizophrenics + 113,000 non-schizophrenics
Dopamine Hypothesis
Too much dopamine activity
Schizophrenics seem to have more D2 receptors on receiving neurones
More dopamine sticks to the neurons allowning firing of neurons more
Snyder
mostly associated with positive symptoms like hallucinations and delusions
Evidence for dopamine hypothesis
Anti-psychotic drugs = main drugs to treat schizophrenia
act by reducing dopamine activity
dopamine antagonists
L-Dopa
treats Huntington's disease
Dopamine agonist
Can lead to schizophrenic side effects to sufferer's of Huntington's
Amphetamines (speed)
Frequent users of speed often get schizophrenia
is a dopamine agonist
Revised dopamine hypothesis
Davis et al.
Not all schizophrenics have high levels of dopamine activity
Some treatment drugs do not block much dopamine but they still seem to be effective in blocking the symptoms
High levels of dopamine in the mesolimbic dopamine system are associated w/ positive symptoms
High levels in mesocortical dopamine system are associated w/ negative symptoms
Evidence
neural imaging
PET scans to assess dopamine levels in schizophrenic + normal people
lower levels of dopamine in the dorsolateral prefrontal cortex of schizophrenic patients compared to control group
Animal studies
Wang and Deutch
Induced dopamine depletion in prefrontal cortex in rats
resulted in cognitive impairment able that researchers were able to reverse using olanzapine, an atypical antipsychoitc drug thought to have beneficial effects on negative symptoms in humans
Neurotransmitter glutamate may be involved
reduced activity of NMDA glutamate receptor
dopamine receptors restric the release of glutamate
Evaluation
Evaluation
Neuro-anatomical
Enlarged ventricles
ventricle is gap between solid matter of the brain
Often schizophrenics have enlarged ventricles
Some don't = not consistent evidence
Psychological
Family Dysfunction
Expressed emotion (too much)
communication style will often express high levels of emotions to each other
In particular, hostile/aggressive emotions being expressed e.g criticism
Can help to cause initial schizophrenia b/c of stress of highly charged environment
When someone is schizophrenic in the family might happen because of schizophrenia (someone critical of schizophrenia or overly concerned)
once someone is schizophrenic, can result in higher relapse rates
Research
Kuipers et al.
High EE relatives talk more and listen less
Linszen et al.
patient returning to family w/ high EE 4x more likely to relapse than family w/ low EE
R.D Laing
Case study of schizophrenic girl called Jane
When he first met her she was completely withdrawn and very emotionally flat
Had recurring fantasy she was a tennis ball involved in a game of mixed doubles
parents had really bad marriage
On dad's side, mother would get involved
On mum's side, father would get involved
When she did talk, she was used as a go between by her parents
Saw herself as tennis ball between mother and father
suggests that schizophrenics have lower tolerance 4 intense environmental stimuli
Double bind
contradictory messages from parents
e.g. mother saying they love child but body language says different (turning head away in disgust)
If this keeps on happening child badly affected
prevents development of internally coherent construction of reality
e.g. flattened affect (emotionally flat) and withdrawal because self protection b/c confused about what is reality
Bateson suggested this
Research
Tienari et al.
level of schizophrenia in adopted biological children of schizo mothers
Cognitive
Maladaptive thought processes cause schizophrenia
Irrational thinking
Faulty thought processing
Can involve problems w/ metacognition
Thinking about thinking
We can usually pick up errors in our cognitive processing
Abnormal people (schizos) cannot do that
They cannot think in such a clear way
Problems with our executive functioning
If you are healthy you will be able to manage all your other thoughts and feelings
Schizos are not able to manage their thinking
Cognitive explanations of positive symptoms
Delusions
Patient;s interpretations of experiences are controlled by inadequateinformation processing
critical component = degree to which perceives themselves as central component in events --> jumps to conclusion about external events
Manifested by tendency to relate irrelevant events 2 themselves + arrive at false conclusions
Muffled vioces interpreted as people criticising them
impervious to reality testing
Beck and Rector = patients r unwilling to consider that they may be wrong
Considered to have "impaired insight"
Inability to recognise cognitive distortions and make more realistic explanations for events
Hallucinations
focus excessive attention on auditory stimuli = higher expectancy for occurrence of hallucination than normal individual
Aleman suggests hallucination prone individuals find it difficult to distinguish between imagery and sensory-based perception
inner representation of an idea can override actual sensory stimulus + produce auditory image (voice)
Baker and Morrison = hallucinating schizophrenics more likely to misattribute source of self-generated auditory experience to external source than non-hallucinating
Cognitive explanations of negative symptoms
occur due to use of cognitive strategies to control high levels of mental stimulation being experienced
may experience greater level of emotion than displayed physically
Interactionist explanation (Diathesis stress model)
Genes would make someone vulnerable to schizophrenia but not necessarily develop it