• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Explain how twin and adoption studies attempt to distinguish genetic and environmental factors underlying the onset of schizophrenia within families. Review the studies and discuss two limitations of this.

Extracts from this document...

Introduction

Psychology Essay Explain how twin and adoption studies attempt to distinguish genetic and environmental factors underlying the onset of schizophrenia within families. Review the studies and discuss two limitations of this. Schizophrenia is the label applied to a group of disorders characterised by severe personality disorganisation, distortion of reality, and an inability to function in daily life. Symptoms are mainly disturbances of thought processes, but also extend to disturbances of emotion and behaviour. There are two symptom categories - acute schizophrenia characterised by positive symptoms, such as hallucinations and delusions; and chronic schizophrenia, characterised by negative symptoms such as apathy and withdrawal. However, DSM-IV has now moved away from these definitions and classified schizophrenia into three main sub-types: paranoid, disorganised and catatonic. Understanding Schizophrenia More research has, probably, been devoted to trying to understand the nature of schizophrenia than any other mental disorder. Somatogenic approaches have focused on the role of genetic mechanisms influencing the propensity to develop schizophrenia, while psychogenic approaches emphasise the effect of adverse childhood experiences, particularly abnormalities in family interaction in the aetiology of the disorder. Twin studies Twin studies offer a powerful method of disentangling the effects of genetic and environmental factors underlying the onset of schizophrenia within families. ...read more.

Middle

The largest study to use the adoptees family design was the Danish adoption study of schizophrenia (Kety, 1983). This found significantly increased risks of developing DSM-III schizophrenia among biological relatives of suffers than among relatives of the control group. However, there was no increased risk among adopted relatives of affected vs. control (Kety, 1983, Kendler et al, 1984). The Finish adoption study of schizophrenia (Tienari et al, 1994) confirmed the genetic contribution in schizophrenia;84% of the adopted offspring with schizophrenia developed a non-affective psychotic disorder, compared with only 0.5% of the adopted offspring of control groups (Tienari et al, 1994). However, a gene-environment interaction also emerged in the study (Wahlberg et al, 1997). When the adoptees were tested for schizophrenia at the mean age of 21, only those adoptees whose biological mother had, had schizophrenia and whose adoptive parents showed high level of communication deviance displayed schizophrenia. This was not observed among adoptees who had only a biological mother with schizophrenia or adoptive parents with a high level of communication deviance (Wahlberg et al, 1997). Adoption studies confirm the importance of genetic factors in the aetiology of schizophrenia - the Finish adoptive study has provided evidence for gene-environment interaction in the development of schizophrenia. ...read more.

Conclusion

Archives of General Psychiatry, 47:622-632. Cited in Gleitman, H, Fridlund, A.J. and Reisbery, D. (1998), Psychology, Norton. Ÿ Cardno et al (1999). Cited in Long, P.W. (M.D.) Internet Mental Health (www.mentalhealth.com) Ÿ Gottesman, I.I., Shields, J. (1982) Schizophrenia: The Epigenetic Puzzle. New York: Cambridge University Press. Cited in Gleitman, H, Fridlund, A.J. and Reisbery, D. (1998), Psychology, Norton. Ÿ Jones, R.E. (1983) Hospital Community Psychiatry, 34:807-811. Cited in Gleitman, H, Fridlund, A.J. and Reisbery, D. (1998), Psychology, Norton. Ÿ Kendler, K.S. and Gruenberg, A.M. (1984) Archives of General Psychiatry, 41:555-564. Cited in Gleitman, H, Fridlund, A.J. and Reisbery, D. (1998), Psychology, Norton. Ÿ Kety, S.S. (1983) Journal of American Psychiatry, 140:720-727. Cited in Gleitman, H, Fridlund, A.J. and Reisbery, D. (1998), Psychology, Norton. Ÿ Kringlen and Cramer, D. (1989). Cited in Long, P.W. (M.D.) Internet Mental Health (www.mentalhealth.com). Ÿ Makikyro et al (1998). Cited in Long, P.W. (M.D.) Internet Mental Health (www.mentalhealth.com) Ÿ Myhrman et al (1996). Cited in The Medical Post (1996) Maclean Hunter Publishing Ltd. Ÿ Ottman (1996). Cited in The Medical Post (1996) Maclean Hunter Publishing Ltd. Ÿ Tienari et al (1994) The Finnish Adoption Study Of Schizophrenia. Cited in Gross, R and McIlveen (1998) Psychology: A New Introduction, Hodder & Stoughton. Ÿ Wahlberg et al (1997). Cited in Long P.W. (M.D.) Internet Mental Health (www.mentalhealth.com) Also used www.schizophrenia.co.uk ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Genetics, Evolution & Biodiversity section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a teacher thought of this essay

5 star(s)

In this well-researched account of the contribution made by genes and the environment to the development of schizophrenia, the writer shows clearly how MZ and DZ twin studies have aided our understanding of the role played by these underlying factors. This is an eloquent piece of scientific writing which wastes few words and relies on a wide range of studies carried out in the latter part of the 20th century. If there is any weakness in the essay, it is that the contribution made to the subject by 21st century DNA sequencing technology has been omitted (e.g. Singh and O'Reilly), but overall, this is an impressive piece of writing given the very small word limit.

Marked by teacher Ross Robertson 09/04/2013

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Genetics, Evolution & Biodiversity essays

  1. Marked by a teacher

    MENTAL HEALTH

    4 star(s)

    and overwhelming that people have great difficult coping with day-to-day activities, such as work, enjoying leisure time and maintaining relationships. At their most extreme, people who are suffering with depression may find it difficult to get themselves out of bed or care for themselves physically.

  2. Edexcel Level 3 Extended Project - Should Embyonic Stem Cell Research be applied to ...

    Bush single-handedly put America lagging behind in the stem cell race, falling far behind countries like Britain and China who were already experimenting on embryos. Being a strong Republican and Methodist, it is unsurprising why he denied more funding into embryonic stem cell research.

  1. Nature Vs Nurture

    The study on 'Susie' whose mother had an IQ in the 40's, and who, after receiving a wealth of 'intelligence fostering intervention', now has two bachelor degrees, demonstrated the independence of an individual's the overall IQ from that of their parents.

  2. A Separate Peace by John Knowles - summary of theme and narrative

    This activity was limited to the seniors training for war, meaning it was off limits for them. But they always played around with rules and got away with it, and it was the same for this time. Well Finny insisted that this time they would jump together and Gene hesitantly agreed.

  1. Phylogenetic tree - in 1866, Ernst Haeckel introduced the phylogenetic tree, or the tree ...

    If the tree of life were real, it would just be real for the time after Cambrian Periods, so is Darwinian Theory because the fossils recording, the existence of Living Fossils and the Cambrian Explosion are the most truthful evidence to reject Darwinian Theory.

  2. Parkinsons Disease

    Most also need to be taken daily for the remainder of a patients lifetime. Many drugs may have minor side affects. Some side affects have social impacts such as mood swings or may not allow the user to fly or travel to certain places.

  1. microbiology ph and temperature effect on bacterial culture

    The results of the bacteria micrococcus luteus at each temperature are shown below Temperature range (degrees) 4 20 35 60 Absorbance group 1 N/a N/a N/a N/a Absorbance group 2 0.03 0.5 0.73 N/a Absorbance group 3 N/a N/a N/a N/a Absorbance group 4 0.01 0.55 0.31 0.01 Absorbance group

  2. Extended essay on “GM Crops”

    Therefore, the random damage resulting from gene insertion will most certainly result in side-effects. Scientists have assessed these risks to be large. Remember, [genetically modified] products are alive. So they're unpredictable in terms of what they'll do once they're out into the environment.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work