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biochemical factors:
- excessive activity of dopamine (specially mesolimbic pathways)
- reduced activity of glutamate
- increased DA activity may block glutamate
- added effect of serotonin/5HT
-
evidence for effect of dopamine
- most antipsychotic meds/neuroleptics that reduce DA activity reduce positive symptoms
- amphetamines and other stims that increase DA activity increase positive symptoms
- increased DA receptors in the brains of schizos
-
flaws with neuroleptic theories:
- tend not to be useful for symptoms
- delay in clinical response to neuroleptics
- HVA not found in excess in cerebrospinal fluid - may be that DA receptors are important, not DA levels.
-
structural abnormalities in schizophrenics
- Kraepelin and others - decrease activity in certain areas (limbic, prefrontal cortex)
- consistent evidence of brain abnormalities
- some abnormalities appear before onset but degeneration continues over time
-
evidence for structural abnormalities
- reduced overall brain weight
- enlargement of ventricles (20-50% of cases) - +ive relationship between enlargement and length/severity of schizophrenia
- cortical atrophy - grooves and clefts are wider
- subcortical atrophy - limbic areas, hippocampus and amygdala
- reduced metabolic activity in the brain
-
delusions
- unrealistic and bizarre beliefs not shared by others in the culture
- may be delusions of grandeur or persecution
-
motivational view of delusions
- these beliefs are attempts to deal with and relieve anxiety and stress.
- a person develops 'stories' around some issue
-
deficit view of delusions
beliefs as resulting from brain dysfunction that creates these disordered cognitions.
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negative symptoms
- indicate absence of insufficiency of normal behaviour
- apathy, limited thought or speech, emotional/social withdrawal
- 25% of schizophrenics display these
-
avolition
inability to initiate and persist in activities
-
alogia
- absence of speech
- reflects negative thought disorder rather than inadequate communication skills
-
affective flattening
- 25% of schizophrenics
- no facial expressions - does not indicate lack of emotion
- speech flat and toneless
- seem unaffected by surrounding events
-
disorganised symptoms
variety of erratic behaviours that affect speech, motor behaviour, and emotional reactions
-
disorganised speech
- jump from topic to topic
- talk illogically
- tangentiality
- derailment
-
inappropriate affect and disorganised behaviour
- laughing or crying at inappropriate times
- hoarding
- catatonia
-
catatonia
- motor dysfunctions that range from wild agitation to immobility
- waxy flexibility
-
paranoid type
- preoccupation with one or more delusions or frequent auditory hallucinations
- cognitive skills and affect are relatively intact
-
disorganised type
- disorganised speech
- disorganised behaviour
- flat or inappropriate affect
- self- absorbed - look in mirror a lot.
- few remissions
-
catatonic type
- motoric inability - catalepsy or stupor
- excessive (purposeless) motor activity
- extreme negativism or mutism
- peculiarities of voluntary movement and posturing
- echoalia or echopraxia
-
residual type
- absence of prominent delusions, hallucinations, disorganised speech, and grossly disorganised or catatonic behaviour
- continuing evidence of the disturbance, with two or more schizo symptoms
-
schizophreniform disorder
- experience symptoms of schizophrenia for a few months only
- good premorbid social and occupational functioning
- absence of blunted or flat affect
- onset of psychotic symptoms within 4 weeks of first change in behaviour
- confusion at height of episode
-
schizoaffective disorder
- uninterrupted period of illness with depressive and/or manic episodes concurrent with schizophrenic symptoms
- 2 weeks of delusions/hallucinations without mood symptoms
-
delusional disorder
- delusions only
- erotomanic
- grandiose
- jealous
- persecutory
- somatic
- mixed
-
erotomanic
delusions that another person, usually of higher status, is in love with the individual
-
grandiose
delusions of inflated worth, power, knowledge, identity, or special relationship to a deity or famous person
-
jealous
delusions that the individuals sexual partner is unfaithful
-
persecutory
delusions that the person (or someone close) is being malevolently treated in some way
-
somatic
delusions that the person has some physical defect or general medical condition
-
mixed type (delusion)
characteristic of more that one of the other types of delusions
-
brief psychotic disorder
- presence of one or more positive symptoms lasting 1 month or less.
- often precipitated by extremely stressful situations
-
shared psychotic disorder
- folie à deux
- individual develops delusions simply as a result of a close relationship with a delusional individual
- delusion is similar in content to that of the delusional other
-
natural history of schizophrenia
-
biological influences
- inherited tendency to develop disease
- prenatal/birth complications - viral infection during preg/birth injury affect child's brain cells
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treatment - individual, group and family therapy
- helps patient and family understand the disease and symptom triggers
- teaches family communication skills
- provides resources for dealing with emotional and practical challenges
-
treatment - social skills training
- can occur in hospital or community settings
- teaches patient social, self-care, and vocational skills
-
treatment - medications
- neuroleptics clarify thinking and perceptions of reality, reduce hallucinations and delusions
- drug treatment must be consistent to be effective. inconsistent dosage may aggravate existing symptoms or create new ones
-
Krystal et al. 2005 - administration of amphetamine and ketamine to healthy Ss
- ketamine blocks glutamate receptors
- amphetamine increases DA activity

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Wong et al. 1986 - D2 receptor density in people with schiz
- measured density of D2 receptors in the caudate

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Suddath et al. 1990 - MRI scans of MZ, schiz discordant twins
found ventricles enlarged in schiz but not non-schiz twins. suggest environment, not genetics
-
Cahn et al. 2002 - change in brain volume
- 34 Ss with first ep psychosis, 36 controls.
- MRI assessed brain volume at baseline and 12 months later.
- only reduction in schiz grey matter
-
Brown & Birley, 1968 - stress
- almost 50% of schizos experience stress 1-3 weeks before onset
- could be result of premorbid symptoms
-
Tienari et al - adoption study
adopted kids of schizophrenic mums only developed severe schizophrenia if they came from maladjusted foster families
-
seasonal evidence for viral infection theory
- in northern hemisphere, schiz more common among people born in Jan-March.
- related to mums becoming sick with the flu earlier in the season, during second trimester
-
Mednick et al. 1988 - Iceland flu
- schiz especially high following major flu epidemic in 1957
- increased proportion only for those in utero in 2nd trimester during epidemic
-
paternal age risk factor
- prevalence 2-3 times higher in offspring of older fathers
- stress hormones increase glucocorticoids but elevated cortisol can potentially damage brain development
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