Neurobiology and management of schizophrenia Flashcards
Schizophrenia is the most common cause of psychosis and is a lifelong condition. True/false?
True
What type of inheritance does schizophrenia have?
Polygenic inheritance
What are some identified gene alterations associated with schizophrenia?
Neuregulin
Dysbindin
DISC-1
What is neuregulin?
A signalling protein that mediates cell-cell interactions and plays critical roles in the growth and development of multiple organs systems.
What is dysbindin?
Essential for adaptive neural plasticity
What is DISC-1?
Involved in neurite outgrowth and cortical development through its interactions with other proteins.
Environmental risk factors for schizophrenia?
- 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.
The dopamine neurons of the dopaminergic pathways synthesize and release the neurotransmitter dopamine. True/false?
True
The dopamine pathways work to transmit the neurotransmitter dopamine around the brain. How many dopamine pathways are there and what are they?
4
nigrostriatal, mesolimbic, mesocortical, and tuberoinfundibular
What is the mesolimbic pathway?
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).
What is the mesocortical pathway?
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.
What is the nigrostratal pathway?
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.
What is the tuberoinfundibular pathway?
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.
Pathophysiology of schizophrenia and the brain?
- 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.
Schizophrenia appearance on CT scan?
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).