Twin Research and Human Genetics

Articles

Genetic and Environmental Contributions to the Overlap Between Psychological, Fatigue and Somatic Symptoms: A Twin Study in Sri Lanka

Harriet A. Balla1 c1, Sisira H. Siribaddanaa2, Athula Sumathipalaa3, Yulia Kovasa4, Nick Gloziera5, Frühling Rijsdijka6, Peter McGuffina7 and Matthew Hotopfa8

a1 MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, United Kingdom. harriet.ball@kcl.ac.uk

a2 Sri Lanka Twin Registry, Institute of Research and Development, Battaramulla, Sri Lanka.

a3 Sri Lanka Twin Registry, Institute of Research and Development, Battaramulla, Sri Lanka; Section of Epidemiology, Institute of Psychiatry, Kings College London, United Kingdom.

a4 MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, United Kingdom; Goldsmiths, University of London, London, United Kingdom.

a5 Sydney Medical School, University of Sydney, Australia; Department of Psychological Medicine, Institute of Psychiatry, Kings College London, United Kingdom.

a6 MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, United Kingdom.

a7 MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, United Kingdom.

a8 Department of Psychological Medicine, Institute of Psychiatry, Kings College London, United Kingdom.

Abstract

Background: Somatic symptoms often co-occur with psychological symptoms but this overlap is poorly understood. Some aspects of this overlap differ in the South Asian context, but it is not clear whether this is a reporting effect or an underlying difference in experienced illness. Methods: Home interviews were administered to 4,024 twins randomly selected from a population-based twin register in the Colombo district of Sri Lanka (the CoTASS study). These included assessments of psychological, somatic and fatigue symptoms. The data were analyzed using factor analytic and quantitative genetic approaches. Results: Confirmatory factor analysis showed that the symptoms from the three scales represented three separate dimensions, rather than all tapping into a single dimension. However, familial correlations among the data were most consistent with a common pathway model. This implies that a portion of the underlying vulnerability is common across psychological, fatigue and somatic symptoms. There were sex differences in the etiology of this model, with shared environmental and genetic influences playing different roles in men and women. Conclusions: There is a complex etiological relationship between psychological, fatigue and somatic symptoms. This is similar in Sri Lanka to Western countries, but there may be a greater influence from the family environment, suggesting that care needs to be taken when generalizing research findings between countries. People who complain of certain fatigue or somatic symptoms may well also have psychological symptoms, or may have genetic or environmental vulnerabilities to such problems.

(Received August 16 2010)

(Accepted November 05 2010)

Keywords

  • genetic;
  • twin;
  • Sri Lanka;
  • somatic;
  • fatigue

Correspondence:

c1 Address for correspondence: Dr Harriet A. Ball, MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, SE5 8AF, UK.

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