biological explanations of schizophrenia Flashcards
what is the first biological explanation of schizophrenia?
genetic factors
this disorder tends to run in families with the risk of developing higher when you have family members with schizophrenia, compared to those who do not
how do family studies measure effects of genetics on schizophrenia?
Gottesmans family study showed that schizophrenia was more common among biological relatives and the closer the relation, the higher the risk
children with two schizophrenic parents had a concordance rate of 46% however this dropped to 13% when this was one parent and again down to 9% when compared to siblings who had schizophrenia
how do twin studies measure the effects of genetics on schizophrenia?
twin studies compare genetically identical twins (who share 100% of the same DNA) and non-identical twins (who share 50%) to measure concordance rates between them
if identical twins have a higher rate then it is believed to be due to genetics however if non-identical twins have a higher concordance rate then it is due to the environment
joseph found that when comparing identical twins studies, they had a concordance rate of 40% while non-identical twins had 7.4%, this higher concordance rate supports the argument for genetic factors.
how to adoption studies measure the effects of genetics on schizophrenia?
adoption studies compared adopted children with biological parent suffering either schizophrenia to a controlled group of adoptees with non-schizophrenic parents.
the aim was to separate the role of nature (genes) and nurture (the environment) in schizophrenia when those related are not together
tienari et al found that out of 164 adopted children who mothers had been diagnosed with schizophrenia, 6.7% of children also shared this diagnosis compared to only 2% out of 197 children with non-schizophrenic mothers
this supported the role of genes influencing the onset of schizophrenia
what is the dopamine hypothesis?
the dopamine hypothesis stars that messages from neurons that transmit dopamine, a neurotransmitter, fire too easily or too often leading to the characteristic symptoms of schizophrenia
schizophrenics are thought to have abnormally high levels of D2 receptors on receiving neurons resulting in more dopamine binding and thus more neurons firing.
what does the revised dopamine hypothesis propose?
the revised dopamine hypothesis focused on high levels of activity of dopamine in the sub-cortex
excess dopamine the broca’s area, which is responsible for speech may be linked with speech poverty or auditory hallucinations
what is another explanation for the revised dopamine hypothesis
the revised dopamine hypothesis also focuses on low levels of activity of dopamine in the prefrontal coretec, which is responsible for thinking and decision making related to negative symptoms of schizophrenia
therefore high and low levels of dopamine in different brain regions are thought to be linked to schizophrenia this way
neural correlates
