Schizophrenia Flashcards
What is Sz?
Bleuler (1908) = Sz term - refers to break from reality
Affects 1% of world pop = ancient writing show disorder has been around for 1000s years
Insel (2010) = as a syndrome, signs + symps w/ unknown aetiology
What are the consequences of Sz?
£ = exceeds cost of all cancers
Assoc w/ higher (13x) suicide rate vs general pop.
what are the symps of Sz?
3 categories = pos. neg. + cogni. –> major symps of Sz are universal + similar across cultures.
Symptoms onset = usually early adulthood, can happen earlier/ later
Appears gradually over 3-5yrs
Neg. symps = first then cognitive. Pos. symps = last
What are pos. symptoms?
Mostly aware of (excess):
- Thought disorders
- Delusions
- Hallucinations
Describe thought disorders as a pos. symptom.
Disorganised, irrational thinking = most important symptoms of Sz
Diff. arranging thoughts logically + plausible conclusions from absurd
During convo = jump from one topic to another bc new associations come up
Utter meaningless words/ choose words for rhyme than meaning
Describe delusions as a pos. symptom.
Delusions = beliefs that are contrary to fact.
There are many types:
* persecution = false beliefs that others are plotting + conspiring against oneself.
Grandeur = false beliefs about one’s power + importance (godlike powers, special knowledge that no one else possesses)
Control = related to persecution i.e the person believes that he or she is being controlled by others through radar/ tiny radio receiver implanted in his or her brain.
Describe hallucinations as a pos. symptom.
Hallucinations = perceptions of stimuli that are not actually present.
Most common are auditory, but they can involve any of the other senses.
- Voices talk to the person, order them to do something, scold the person for his or her unworthiness or utter meaningless phrases.
Olfactory hallucinations = fairly common + often contribute to delusion: others trying to kill them
What are negative symps?
Absence or diminution of normal bhvrs:
- flattened emotional response
- poverty of speech
- lack of initiative
- persistence
- anhedonia = reduced ability to feel pleasure
- social withdrawal
What are cognitive symps?
Difficulty in sustaining attention
Low psychomotor speed (ability to rapidly + fluently perform mvmnts of the fingers, hands, and legs)
Deficits in learning and memory
Poor abstract thinking
Poor problem solving
How are cognitive symptoms caused in the brain?
All neurocognitive deficits assoc. w/ frontal lobe hypofunction
Weinberger (1988) suggested neg. symps of Sz =
caused primarily by hypofrontality, decreased activity of the frontal lobes, the dlPFC in particular
Causes:
* Lower performance in IQ tests
* Planning and information processing deficits
* Attentional deficits (e.g. Stroop test)
* Working memory deficits (e.g. Wisconsin Card Sorting Test)
* Sensory-motor gating deficits (P50 and PPI tasks)
* Anti-saccade task
* Oculomotor function (eye tracking)
(McDonald et al., 2005)
What is the stroop test?
Congruent + incongruent = name the colour ink
Sz Ps = slower + less accurate
involves inhibiting tendency to read words
What is the Wisconsin Card sort test?
Normal = during task there is an increase in regional blood flow to the diPFC (shown in fMRI)
SZ = no increased blood flow in the frontal lobe
How are sensory-motor gating deficits linked to SZ?
sensory-motor gating deficits = difficulties screening out irrelevant stimuli + focusing on salient ones
P50 signal in ERPs (Event-Related Potentials)
- Presented 2/ 2 auditory stimuli (2 clicks) 500ms apart
- Healthy response - P50 wave to 2nd click is 80% diminished vs Sz Ps there is no change
What does Pre-pulse inhibition show sensory-motor gating deficits?
Pre-pulse inhibition (PPI) = when weak stimulus precedes a startle stimulus by around 100ms, the normal response is to inhibit the startle
People w/ Sz can’t inhibit the startle
How is the oculomotor function affected when having Sz?
Smooth pursuit = tracking a moving stimulus
Eye movement of Sz Ps = not smooth vs controls
What are the structural differences in the brain for people w/ Sz?
Weinberger and Wyatt (1982): CT scans of 80 schizophrenics + 66 healthy controls of the same mean age (29y) and measured the area of the lateral
ventricles (blind study)
Relative ventricle size Sz Ps = > 2x big vs control
Reduced brain volume (less grey matter) in temporal, frontal lobes + hippocampus
Faulty cellular arrangement in the cortex + hippocampus
What is the heritability of Sz?
Adoption + twin studies = Sz is heritable trait but not bc single dominant/ recessive gene
No single gene = causation = polygenic
Having Sz gene = susceptibility to be triggered by environment
What are the genetics of SZ?
1 rare mutation = DISC1 (disrupted in Sz 1)
- involved in regulation of neurogenesis, neuronal migration, postynpatic density in excitatory neurons + mitochondria function
- Presence = increase chance of Sz by 50 - Increases incidence of other mental health conditions e.g BP + Autism spectrum disorder (ASD)
MZ twins = 48%. If one twin has Sz, other twin will have…
Dz = 17%
How is paternal age linked to Sz?
Effect of paternal age = further evidence that genetic mutations may affect the incidence of schizophrenia (Brown et al., 2002; Sipos et al., 2004).
- The children of older fathers are more likely to develop schizophrenia.
- Probs bc mutations in the spermatocytes (the cells produce sperm)
- After puberty, cells divide every 16 days = divided approximately 540 times by age 35
- VS a woman’s oocytes divide 23 times before birth + only once after
What do twin studies show about Sz?
Mz = genetically identical + share same environment, but prenatal environment is not always identical
- formation of MZ twins = when blastocyst splits in 2
- happens after day 4 = 2 organisms become monochromic (share a placenta)
Concordance rate for monochorionic MZ twins = 60^ vs dichorionic MZ twins ( David and Phelps, 1995)
What are early neurodevelopmental theories of SZ?
Events in early life (prenatally) = deviations from normal
neurodevelopment + dormant until the brain matures
sufficiently to call into operation the affected systems (Murray & Lewis, 1987)
Early events e.g infections, obstetric complications, nutritional deficiencies etc. = support of this theory.
What early evidence support abnormal brain development?
Home movies from families Sz child (Walker et al 1994,1996)
- Independent observers examined the bhvr of children
- Those who = SZ displayed more negative
affect in their facial expressions + were more likely to do abnormal movements.
In 1972, 265 Danish children aged 11–13 years = videotaped briefly while eating lunch (Schiffman et al. 2004)
- Blind raters, found that the children = w/ SZ displayed less sociability + displayed deficient psychomotor functioning.
What is the late neurodevelopment model?
Sz = result from in abnormality or deviation in adolescence, when synaptic pruning takes place (Feinberg, 1982)
What is the two hit model?
Atypical devlpmnt in SZ = during 2 critical time points:
early brain development + adolescence
Early developmental insults = dysfunction of spec. neural networks that account for premorbid signs
During adolescence, excessive synaptic pruning + loss of plasticity = emergence of symptoms.
