Schizo - Biological - Genes Flashcards
How do genes work and relate to schizo
Genes determine physical features such as hair and eye colour but there is growing evidence that genes we inherit from our parents can also play a key role in our vulnerability to mental illnesses such as schizophrenia. This explanation states schizophrenia is a genetic illness
How do ‘family studies’ relate to schizophrenia with two cases?
Family studies are used to investigate the genetic element of schizophrenia by comparing rates of schizophrenia in families with a member with schizophrenia diagnoses to control group families
Kety et al. Studied 207 children of schizophrenic mothers in comparison to a matched pairs group of 104 children with healthy mothers.
Follow ups conducted 12 and 15 years later showed schizophrenia was diagnosed in 16.2% of the experimental group and just 1.9% in the control group
Give a weakness of the use of family studies
One issue with Family studies is that it is hard to establish cause and effect as the closer that you are genetically to someone, the more likely you are to share an environment. For example, children are highly likely to live with their parents and siblings, and less likely to live with grandparents or cousins. This is an issue when attempting to draw conclusions as it may be the similar environment causing schizophrenia rather than the similar genes which causes the high concordance rate. As it is a non-experimental method, we cannot establish a clear cause-and-effect relationship.
How are Twin studies used in schizophrenia
Twin studies are useful as we can establish a genetic correlation by looking at concordance rate of 50% and 100% of genetics using MZ and DZ twins.
Gottesman (1991) summarised 40 studies and found overall a 48% correlation for MZ twins and just 17% for DZ twins
The biggest weakness of twin studies is that it is difficult to establish clear cause and effect due to the role of nature and nurture as twins not only share genes, but they also often share an environment. Twins are likely to attend the same school, live in the same house and be raised with the same parenting style. Therefore, psychologists are limited in their ability to separate the effects of genes from the environment. Therefore, as twin studies are a non-experimental method, we cannot establish a cause-and-effect relationship. A high concordance rate may not necessarily be due to shared genes, there may be extraneous variables that interfere with the results.
Give another weakness of twin studies
Studies that compare identical twins with non-identical twins also assume that the only difference between the two types is the higher percentage of genes shared by identical twins. However, Joseph (2004) points out that identical twins are often treated more similarly that non-identical twins, for example being dressed the same and being referred to as ‘the twins’ rather than two separate people. They also experience much more identity confusion than non-identical twins. He argues therefore that the higher concordance rate may be nothing more than the effect of a shared environment rather than genes
How are adoption studies used in Schizophrenia studies
Tienari 1987 conducted a Finnish adoption study using a sample of children given up for adoption by schizophrenic mothers and compared them to a control group. Found that the experimental group of schizophrenic biological mothers had a 7% chance of developing schizophrenia and those in the control group with non-schizophrenic mothers had a 1% chance of developing schizophrenia. Tienari concluded that having a biological mother with schizophrenia increased the rate of schizophrenia in the adoptees, even if they were adopted by non-schizophrenic families. However, he found that the schizophrenic gene only revealed itself if the new adoptive family was psychologically disturbed in some way. Meaning even vulnerable individuals could be protected from schizophrenia if the family who raised them was healthy.
Adoption studies are useful as unlike twin and family studies there is no element of nature, as they are not in the same environment as their schizophrenic mother. This is a strength as it allows us to draw more definite and concrete conclusions about the effects of genes and schizophrenia.
Give a weakness of the use of adoption studies in schizophrenia
However, as a non-experimental method was used, we cannot establish clear cause and effect relationships.
Some children are adopted at birth, while others are adopted months or even years later. For such children, they have spent more time in a shared environment with their biological parent. Therefore, we may not be separating genes and environment as clearly as would be ideal.
Even children who are adopted at birth may still have been shaped by their biological mothers in the womb. If a woman smokes, drinks or takes drugs during pregnancy, long term effects may occur in her child.
There is also the issue that people who place their children for adoption may be more likely to suffer from mental illnesses. Therefore, care needs to be taken when using adoption studies to investigate the genetic basis for mental illness as we may find a high concordance between biological parents and their children on this factor. This may come simply from this sample bias.
