Psychosis basic sciences

Question 1

what is heritability?

Answer 1

Proportion of observable differences in a trait between individuals in a population that’s due to genetic differences

Question 2

What obstetric problems are associated with schizophrenia?

Answer 2

• children exposed to viral illness during 2nd trimester/pregnancy have slightly increased risk
• pre-eclampsia
• fetal hypoxia
• emergency c-section

Question 3

What childhood illness is associated with schizophrenia?

Answer 3

-childhood viral CNS infection increases risk of schizophreia by 50%

Question 4

Consumption of what drug is associated with schizophrenia?

Answer 4

-studies have shown that there’s a higher number of cases of schizophrenia in those that have consumed cannibis at age 18

Question 5

Describe some brain structure abnormalities that are associated in schizophrenia patients with poor prognosis

Answer 5

• decreased frontal lobe volume and grey matter

- enlarged lateral ventricle volume

Question 6

Grey matter abnormalities and schizophrenia:

• when are abnormalities present?
• is this progressive?
• what is the abnormality and what is this due to?

Answer 6

• abnormalities are present in early illness and likely pre-morbidly
• likely progressive in initial years of illness
• grey matter reductions due to reduced aborisation (dendritic branching) and NOT neuron loss

Question 7

Why are white matter abnormalities hypothesised in schizophrenia?

Answer 7

hypothesis of abnormal ‘neural integration’ in schizophrenia, white matter connects different brain regions and therefore white matter abnormalities hypothesised in schizo.

Question 8

Is there a role for neuroimaging in schizophrenia?

Answer 8

abnormalities show average brain of schizophrenia is abnormal to the average brain of controls however due to normal variation in healthy brain structure this can’t be used clinically

Question 9

what is the dopamine hypothesis in schizophrenia?

Answer 9

it is assumed that schizophrenia is related to the overactivity of D2 pathways in the brain

• antipsychotics block D2 receptors
• dopamine agonists and dopamine releasing drugs produce psychotic states
• Amphetamine worsens schizo symptoms (works to expel dopamine)

Question 10

What are the three different systems that are controlled by dopamine release?

Answer 10

• Tuberoinfundibular pathway: control of prolactin release
• Nigrostriatal pathway: extrapyramidal motor system
• Mesolimbic/cortical system: motivation and reward systems

Question 11

What is the abnormality of dopamine activity in psychosis vs -ve/cognitive symptoms?

Answer 11

-Subcortical DA hyperactivity leads to psychosis
-Mesocortical DA hypoactivity leads to -ve/cognitive symptoms
(this is based on evidence that -ve/cognitive symptoms persist despite D2 blockade)

Question 12

What is the glutamate hypothesis of schizophrenia?

Answer 12

-there is altered NMDA (glutamate) receptor subunit expression

Question 13

What is the serotonergic hypothesis?

Answer 13

-serotonin 2A binding potential in frontal cortex index smaller in schizophrenia

Question 14

How does alteration in the neuregulin gene cause brain pathology?

Answer 14

This is codes for a signalling protein = mediates cell to cell interactions and plays critical role in growth and development of multiple organ systems

Question 15

How does alteration in the dysbindin gene cause brain pathology?

Answer 15

essential for adaptive neuroplasticity

Question 16

How does alteration in the DISC-1 gene cause brain pathology?

Answer 16

involved in neutrite outgrowth and cortical development through its interaction with other protein