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Terms in this set (57)

Evidence for a genetic predisposition
Twin studies
50% concordance in MZ twins
17% concordance in DZ twins
No specific genes found (yet)
The complicated and different types of schizophrenia may be controlled by different genes.
Or, schizophrenia may be due to a combination of gene defects

Prenatal (or early post natal) viral infections
Increased risk of schizophrenia if flu epidemic during 2nd trimester of fetal development
Virus may impair fetal brain development
60% concordance in MZ twins who share single placenta (only 10% in MZ twins with separate placenta)
sharing a viral infection more likely if share same placenta
Risk of schizophrenia also associated with early exposure to herpes simplex virus and toxoplasma gondii (parasite transmitted in cat feces)

The dopamine hypothesis
schizophrenia is linked to
abnormally high levels of dopamine, or
excess receptors for dopamine
dopamine agonists increase symptoms of schizophrenia
dopamine antagonists reduce symptoms of schizophrenia
some antipsychotic drugs are dopamine antagonists (work to control Type 1 schizophrenia)

Glutamate dysfunction
Some psychedelic drugs (e.g. PCP) cause:
reduced speech
motor disturbances
other cognitive deficits
similar to some of the negative symptoms of schizophrenia
PCP works by blocking glutamate receptors
a major excitatory neurotransmitter in the brain

Brain abnormalities
These are especially found in patients with Type II schizophrenia
Shrunken cerebral tissue
Enlarged fluid filled areas
The thalamus seems to be smaller
Less activity in the frontal lobes

The vulnerability-stress model
A bio-psycho-social explanation
Genetic, prenatal, and postnatal biological factors render a person vulnerable to schizophrenia, but environmental stress determines whether it develops
Our level of vulnerability combined with stressful social-cognitive events in our lives determines the likelihood of schizophrenia
e.g., schizophrenia tends to strike in late adolescence and early adulthood — periods of unusually high stress