Neurobiology of Psychosis Flashcards
A man believes that his parents are trying to poison him because the government are controlling them.
Which psychopathology term is this describing?
Paranoid Delusion
A man believes that news articles on the television about world leaders’ phones being tapped are actually talking about him as he holds important government information.
Which psychopathology term is this describing?
Ideas of Reference
When a man listens to the radio he can hear voices from elsewhere in the room telling him he must not think about the military information he has been given.
Which psychopathology term is he describing?
Functional hallucination
- hallucinations triggered by a stimulus in the same modality
- e.g. radio is an auditory stimulus and the man is having auditory hallucinations
A man believes he must not think about the military information as everyone else has access to his thoughts.
Which psychopathology term is he describing?
Thought Broadcasting
There is a higher genetic risk of a psychiatric condition in dizygotic twins than between 1st degree relatives. Why is this?
More environmental similarities (before and after birth) between dizygotic twins than first degree relative (even another sibling)
What structural brain abnormalities present in Schizophrenia patients with poor prognosis?
Reduced frontal lobe volume
Reduced frontal lobe grey matter
Enlarged lateral ventricle volume
Abnormalities of the brain’s grey matter usually present early in schizophrenia and are thought to exist pre-morbidly. TRUE/FALSE?
TRUE
Grey matter reduction is likely to progress in the initial years of schizophrenia. TRUE/FALSE?
TRUE
What causes grey matter reduction in schizophrenia?
reduced arborisation (branching of end of nerve fibre)
NOT due to neuron loss
How are white matter abnormalities in the brain investigated in schizophrenia?
‘diffusion tensor imaging’ (DTI)
Measured using:
‘fractional anisotropy’ (FA)
- high number = healthy white matter tracts
‘mean diffusivity’ (MD)
- high number = unhealthy white matter tracts
It is assumed that schizophrenia is related to overactivity of Dopamine pathways in the brain. TRUE/FALSE?
TRUE
This is because:
- Drugs which release Dopamine in the brain
produce a psychotic state in man.
- Dopamine receptor antagonists are used to treat the symptoms of schizophrenia.
Explain the difference between action of D1 and D2 receptor subtypes?
D1 (and D5) receptor:
- stimulates cAMP
- more abundant than D2
D2 receptor family (D2,D3,D4):
- inhibit Adenylyl Cyclase
- inhibit Ca2+ channels
- open K+ channels
- more widespread in CNS
Give an example of a D2 agonist and a D2 antagonist
AGONIST - ropinirole (D2,3,4 but highest affinity for D2)
ANTAGONIST - Haloperidol
What hypothesis has been generated after proof that negative and cognitive symptoms persist despite D2 blockade with antipsychotics?
- The dopamine system is dysfunctional?
- Subcortical Dopamine HYPERactivity leads to psychosis
- Mesocortical Dopamine HYPOactivity leads to negative and cognitive symptoms
What neurotransmitter problems have been hypothesised to explain schizophrenia?
Glutamate:
- altered NMDA receptor subunit expression
Serotonin
- abnormalities in serotonin 2A binding in the frontal cortex significantly smaller in schizophrenia patients
