Neurobiology of Psychosis Flashcards
WHat percent is Schizo heritable?
78% heritable
Define heritability.
- the proportion of observable differences in a trait between individuals in a popn (d.t genetic diff.)
Why is childhood hx important with suspected Schizophrenia?
2nd trimester illness is a/w with increased risk of Schizo developing by 50%
- Obstetric problems-pre-eclampsia/ fetal hypoxia/ emergency C-section
What drug is least likely to induce psychosis?
- Cannabis
- a.w LATER risk of schizo
How does the coronal section of the brain appear for poor prognosis?
- reduced frontal lobe volume
- reduced frontal lobe GREY matter
- enlarged LATERAL ventricle volume
What is neuropril? Where is it predominantly found?
- any area in the NS composed of UNMYELINATED axons, dendrites, and glial cells
- synaptically dense region with LOW cell bodies
- —NEOCORTEX and OLFACTORY bulb
Where is GREY MATTER seen to be reduced in a brain of schizophrenic?
CONSISTENT reductions seen in temporal cortex and medial temporal lobe
Variable reductions seen in orbitofronal cortex, parietal cortex, basal ganglia
Why is white matter abnormalities considered to also be pathological in schizo?
- normal cognitive functions are partly localized a schizo brain
- but there is abnormal NEURAL intergration in schizo (white matter is said to CONNECT diff. parts oft the brain)
How to explore the extent of white matter damage?
- DTI (diffuse tensor imaging)
- –MD-Higher numbers= less healthy WM tracts
- —FA- higher numbers= more healthier WM tracts
WHat does a higher FA mean in DTI?
- –correlates with psychotic symptom severity
- –d/t myelin abnormalities
What causes the brain pathology in schizo?
- Neuregulin (critical in growth and develop. of multiple ORGAN systems)
- Dysbudin (essential for adaptive neural plasticity)
- DISC-1 (invovled in cortical developm.)
How does blocking DOPAMINE cause osteoporosis?
- dopamine is said to have an inhibitory effect on the pituitary release of Prolactin
- –no dopamine release= HYPERPROLACTINEMIA
> reduce estrogen and testosterone levels >OP
Action on what receptors results in Positive psychotic symptoms?
- 5-HT2A
>hallucinations and thought disturbance
What occurs with antagonism of the H1 receptors centrally?
- central antagonism: SEDATION, loss of APPETITE
- reduces nausea and vomitting
WHat occurs with reduction of Alpha1-Adrenergic activity of blood vessels?
Hypotension and interruption of baroreflex response
> dizziness, lightheadedness when rising from a LYING/SITTING position
Blocking dopamine receptors in the pituitary gland brings out what S.Es?
- sexual dysfxn
not acromegaly/sedation/akathesia
Antipsychotic acting on what receptors is avoided in pts, at risk of falls (old and frail, already on anti-hypertensives)
- alpha-adrenergic
- histamine blockade
What is given for rx of treatment-resistant Schizo?
- Clozapine
Huge side effect of Clozapine (Atypical Anti-psychotics)?
- Agranulocytosis
How often must one get their FBC checked when on Clozapine?
- for 6 months: WEEKLY
- next 6 months: FORTHNIGHTLY
- afterwards: every 4 WEEKS
- for ONE month after CESSATION
In what special situation is an fbc ordered in when a patient is also on Clozapine?
- when they have any form of Infection
- get FBC (even if it’s a sore throat)
What metabolizes clozapine faster?
- not smoking
Likelihood of becoming schizophrenic is a first degree relative is schizo?
11%
What occurs with subcortical dopamine HYPERactivity and MESOCORTICAL dopamine hypoactivity?
- subcortical dopamine hyperact/=> PSYCHOSIS
- Mesocortical dopamine hypoactivity=> negative cognitive symptoms
