Biological Explanations Of Schizophrenia Genetics Flashcards
How are adoption studies useful?
- it is difficult with twin studies to separate the effect of heredity from the effects of the environment because twins are usually raised together
- adoption studies allow researchers to look at people born to schizophrenic mothers but brought up by people with no history of the disorder.
Kety study:
Found high rates of schizophrenia in individuals whose parents had the disorder but had been adopted
Tienari study:
Finnish adoption study found 155 adopted children whose biological mothers had schizophrenia and compared them with a matched group of adopted children who had no family history of schizophrenia
RESULTS: found 10% of the adopted group whose mother had schizophrenia developed schizophrenia compared to 1% of the second group
These studies provide strong evidence for a genetic component BUT IT IS A COMPLEX ISSUE
What have family studies shown about schizophrenia?
That it’s not just twins who are of interest but the entire immediate family eg.
MZ twins 85.8% chance
Full sibling 14.3% chance
Parents 9.2% chance
Co-morbidity between family:
Reed et al.
It is clear from the figures that the closer the genetic link, the higher the concordance rate.
But Reed et al. showed that the relationship is not that simple, as when he used patents with psychosis rather than schizophrenia they found that if the mother had psychosis then the risk of her child was 20% whereas if the father had psychosis, the risk to the child was only 8%
Conclusions of the influence of genetics on schizophrenia:
- strong argument for a genetic link however both nature and nurture influence it, otherwise MZ concordance rates would be 100%
- Gottesman and Shields concluded that both genes and environment are each necessary but not sufficient for developing schizophrenia.
Epigentics - the environment effects the way our genes are expressed
