(PM3B) Psychosis & Schizophrenia Flashcards
What is psychosis?
Syndrome (a set of symptoms)
- Delusions/ hallucination/ disorganised speech or behaviour/ distortion of reality
Can be associated with Alzheimer’s disease, depression, cognitive disorders + mania
What is split personality a symptom of?
NOT schizophrenia
Multiple personality disorder
Very rare
Describe the aetiology of schizophrenia.
Onset – adolescence/ early adulthood
~1% lifetime risk
Higher incidence in lower socioeconomic groups
What role do genetics play in schizophrenia?
No single gene responsible (multiple which can increase risk)
Tends to be genetic
How is it known that schizophrenia is partly inherited?
Studies on identical twins
If identical twins are raised separately and one of them develops schizophrenia, what is the likelihood the other isolated twin will also develop this?
50%
1 in 2
If fraternal twins are raised separately and one of them develops schizophrenia, what is the likelihood the other isolated twin will also develop this?
12.5%
1 in 8
What neuropathological changes can be observed?
(1) Enlarged ventricles
(2) Reduced temporal lobe volume – post-mortem
(3) Reduce cerebral blood flow -> reduced frontal function
(4) Non-progressive
Which area(s) of the brain is/ are responsible for aggressive symptoms of schizophrenia?
(1) Orbitofrontal cortex
(2) Amygdala
Which area(s) of the brain is/ are responsible for affective symptoms of schizophrenia?
Ventromedial prefrontal cortex
Which area(s) of the brain is/ are responsible for positive symptoms of schizophrenia?
Mesolimbic pathway
Which area(s) of the brain is/ are responsible for negative symptoms of schizophrenia?
(1) Mesocortical
(2) Prefrontal cortex
(3) Nucleus accumbens (rewards circuits)
Which area(s) of the brain is/ are responsible for cognitive symptoms of schizophrenia?
Dorsolateral prefrontal cortex
What are some positive symptoms of schizophrenia?
(1) Delusions
(2) Hallucinations
What are some negative symptoms of schizophrenia?
(1) Apathy
(2) Anhedonia – inability to feel pleasure in normally pleasurable activities
(3) Cognitive blunting
(4) Neuroleptic dysphoria – unpleasant changes of thinking
What are some inherited genetic factors of schizophrenia?
(1) Increased risk in families when 1 member is affected
(2) Susceptibility with certain genes – e.g. neuregelin 1
What is the significance of the neuregelin 1 gene?
Increases susceptibility of schizophrenia development
What are some environmental factors which may increase the susceptibility of developing schizophrenia?
(1) Birth complications
(2) Viral infection
(3) Immigration
(4) Drug misuse
(5) Inner cities
With regard to schizophrenia, what is the neurodevelopmental model?
Poor environment/ genetic factors
Lead to changes in brain development
Contribute to risk
What is the dopamine hypothesis?
Role of onset of schizophrenia
How is dopamine produced?
In dopaminergic neurones
What does dopamine bind to?
Dopamine receptors
D1-D5
What is the role of COMT in the synaptic cleft?
Breakdown of dopamine
What is the function of dopamine autoreceptors (D2)?
Is a presynaptic autoreceptor
Prevents the release of further dopamine
Negative feedback mechanism
Where can dopamine autoreceptors (D2) be found?
(1) Presynaptic membrane
(2) Somatodendritic
What is the mesolimbic pathway?
Reward/ dopaminergic pathway
Begins with ventral tegmental area (VTA) + ends with nucleus accumbens
In schizophrenia, what is the effect of the mesolimbic pathway?
Dopamine pathways are hyperactive
Release too much dopamine
Leads to positive symptoms
In schizophrenia, what is the effect of the mesocortical dopaminergic pathway?
Hypoactivity
Releasing too little dopamine
Selective neural degeneration of mesocortical dopaminergic production
Leads to negative symptoms