Neurobiology and management of schizophrenia

Question 1

Schizophrenia is the most common cause of psychosis and is a lifelong condition. True/false?

Answer 1

True

Question 2

What type of inheritance does schizophrenia have?

Answer 2

Polygenic inheritance

Question 3

What are some identified gene alterations associated with schizophrenia?

Answer 3

Neuregulin

Dysbindin

DISC-1

Question 4

What is neuregulin?

Answer 4

A signalling protein that mediates cell-cell interactions and plays critical roles in the growth and development of multiple organs systems.

Question 5

What is dysbindin?

Answer 5

Essential for adaptive neural plasticity

Question 6

What is DISC-1?

Answer 6

Involved in neurite outgrowth and cortical development through its interactions with other proteins.

Question 7

Environmental risk factors for schizophrenia?

Answer 7

• 2nd trimester viral illness
• Obstetric problems - pre-eclampsia, foetal hypoxia, emergency caesarian section
• Childhood viral CNS infection - increases risk by 50%
• Substance misuse, especially cannabis:
  • Risk of psychosis is increased by: amphetamines, cocaine, cannabis, “legal highs” etc.
  • In individuals predisposed to schizophrenia, drug use may precipitate an episode and worsen overall prognosis.

Question 8

The dopamine neurons of the dopaminergic pathways synthesize and release the neurotransmitter dopamine. True/false?

Answer 8

True

Question 9

The dopamine pathways work to transmit the neurotransmitter dopamine around the brain. How many dopamine pathways are there and what are they?

Answer 9

4
nigrostriatal, mesolimbic, mesocortical, and tuberoinfundibular

Question 10

What is the mesolimbic pathway?

Answer 10

This pathway is highly involved in dopamine’s most commonly thought of function: pleasure and reward. This pathway begins at the ventral tegmental area (VTA).

Question 11

What is the mesocortical pathway?

Answer 11

Like in the mesolimbic pathway, dopaminergic projections within the mesocortical pathway originate in the VTA.

When dysfunction within this pathway occurs, individuals may experience poor concentration and the inability to make decisions.

Question 12

What is the nigrostratal pathway?

Answer 12

Involved in motor planning. As the name implies, the dopamine projections start in the substantia nigra and go to the caudate and putamen, parts of the basal ganglia.

Question 13

What is the tuberoinfundibular pathway?

Answer 13

The dopamine neurons in this pathway begin in the arcuate and periventricular nuclei of the hypothalamus, and project to the infundibular region of the hypothalamus, specifically the median eminence.

Dopamine is released into the portal circulation that connects this region to the pituitary gland. Here, dopamine functions to inhibit prolactin release.

Question 14

Pathophysiology of schizophrenia and the brain?

Answer 14

• Mesolimbic pathway has been disrupted.
• Robust finding of enlarged ventricles, shows little progression over time.
• Reduced fronto-temporal volume
• Reduced activation of prefrontal areas on specific tasks e.g. Stroop test.

Question 15

Schizophrenia appearance on CT scan?

Answer 15

Ventricular enlargement is present at diagnosis and is non-progressive.

There is no gliosis (when the body creates more or larger glial cells - cells that support the nerve cells).

Question 16

Schizophrenia environmental risk factors act in utero. True/false?

Answer 16

True, the environmental risk factors for schizophrenia act in utero (before birth).