Genetic and Environment in Mental Health: Twin Studies

Abstract

The purpose of the current study is to portray the twin research characteristics as a valuable information source to the fields of psychiatry and psychology. Twin research focuses on determining the boundaries between environment and heredity. The emphasis on the importance of genetic and environmental factors in current twin researches is remarkable and constitutes one of the main highlights of this review. For researchers, twin studies involve mainly prominent components in the planning and designing of twin research. These components are ‘the reasons for twin research preference, ‘basic underlying assumptions,’ ‘limitations,’ and ‘current approaches to be preferred’ in twin research. For this reason, these main components will be discussed. Fourteen twin research designs are defined, which were prescribed by the proponents of twin research, and the findings are also indicated. It is seen that some of these researches are frequently preferred in the field, but some of them are carried out in a limited number due to sampling difficulties. However, when all research designs are examined concerning the literature review, it can be concluded that specifying the interactions of genetics and environment in twin research still maintains its importance researchers about the limitations of twin research.

Keywords

• Twins,twin research designs,genetic,environment

Ruh Sağlığı Alanında Genetik ve Çevre: İkiz Araştırmaları

Abstract

Bu çalışmanın amacı, psikiyatri ve psikoloji alanları için önemli bir bilgi kaynağı olan ikiz araştırmalarının betimlenmesidir. İkiz araştırmaları, çevre ve kalıtım arasındaki sınırları belirlemeye odaklanmaktadır. Özellikle bu konuda yürütülen güncel araştırmalarda genetik ve çevresel faktörlerin önemine yapılan vurgu dikkate değerdir ve bu derleme çalışmasının da ana vurgularından birini oluşturmaktadır. Araştırmacılar için, ikiz araştırmalarının planlanmasında ve tasarlanmasında öne çıkan temel bileşenler, “çalışma deseni olarak ikiz araştırmalarının tercih edilme nedeni”, “ikiz araştırmalarında kullanılan temel varsayımlar”, “ikiz araştırmalarının sınırlılıkları” ve “yöntem olarak tercih edilen güncel ikiz desenleri”dir. Bu sebeple öncelikle bu temel bileşenlerden bahsedilecektir. Alanyazında öncü sayılan araştırmacılar tarafından tanımlanan ve ikiz araştırmalarında sıklıkla kullanılan on dört ikiz araştırması deseni ve bu araştırma desenlerinin kullanıldığı araştırma bulgularına da yer verilmiştir. Bu araştırmaların bazılarının alanda sıklıkla tercih edildiği, bazılarının ise örneklem zorluğu nedeniyle sınırlı sayıda yürütüldüğü görülmektedir. Ancak tüm araştırma desenlerinde, genetik ve çevrenin karşılıklı etkileşimlerine vurgu yapan araştırmaların, araştırmacılar için güncelliğini ve önemini koruduğu görülmektedir. Son olarak, ikiz araştırmalarının sınırlılıkları hakkında prospektif araştırmalara yönelik önerilerde bulunulmuştur.

Keywords

• ikizler,ikiz araştırma desenleri,çevre,genetik

References

1. Asbury, K., Moran, N., & Plomin, R. (2016). Non shared environmental influences on academic achievement at age 16: A qualitative hypothesis-generating monozygotic-twin differences study. AERA Open, 2(4), 1–12. doi: 10.1177/2332858416673596
2. Asbury, K. ve Plomin, R. (2014). Genlerin G’si. (D. Boyraz, Çev.). İstanbul: Sola Unitas.
3. Beaver, K. M., Boutwell, B. B., Barnes, J. C., Schwartz, J. A., & Connolly, E. J. (2014). A quantitative genetic analysis of the associations among language skills, peer interactions, and behavioral problems in childhood: Results from a sample of twins. Merrill-Palmer Quarterly, 60(2), 142– 167. doi: 10.13110/merrpalmquar1982.60.2.0142
4. Becker‐Blease, K. A., Deater‐Deckard, K., Eley, T., Freyd, J. J., Stevenson, J., & Plomin, R. (2004). Genetic analysis of individual differences in dissociative behaviors in childhood and adolescence. Journal of Child Psychology and Psychiatry, 45(3), 522–532. doi: 10.1111/j.1469- 7610.2004.00242.x
5. Benner, A. D., Kretsch, N., Harden, K. P., & Crosnoe, R. (2014). Academic achievement as a moderator of genetic influences on alcohol use in adolescence. Developmental Psychology, 50(4), 1170–1178. doi: 10.1037/a0035227
6. Blonigen, D. M., Hicks, B. M., Krueger, R. F., Patrick, C. J., & Iacono, W. G. (2006). Continuity and change in psychopathictraits as measured via normal-range personality: A longitudinal- biometric study. Journal of Abnormal Psychology, 115(1), 85–95. doi:10.1037/0021- 843X.115.1.85
7. Bouchard, T. J., Lykken, D. T., McGue, M., Segal, N. L., & Tellegen, A. (1990). Sources of human psychological differences: The Minnesota study of twins reared apart. Science, 250(4978), 223– 228. doi: 10.1126/science.2218526
8. Bouchard, T. J, Thomas, J., & Propping, P. E. (1993). Life sciences research report. Twins as a tool of behavioral genetics. Oxford, England: John Wiley & Sons.

9. Breitner, J. C., Gau, B. A., Welsh, K. A., Plassman, B. L., McDonald, W. M., Helms, M. J., & Anthony, J. C. (1994). Inverse association of anti‐inflammatory treatments and Alzheimer's disease: Initial results of a co‐twin control study. Neurology, 44(2), 227–232. doi: 10.1212/WNL.44.2.227
10. Brown, D. (2002). Career choice and development. San Francisco: Jossey Bass.
11. Burt, S. A. (2009). Rethinking environmental contributions to child and adolescent psychopathology: A meta-analysis of shared environmental influences. Psychological Bulletin, 135(4), 608–637. doi: 10.1037/a0015702
12. D'onofrio, B. M., Turkheimer, E., Emery, R. E., Maes, H. H., Silberg, J., & Eaves, L. J. (2007). A children of twins study of parental divorce and offspring psychopathology. Journal of Child Psychology and Psychiatry, 48(7), 667–675. doi: 10.1111/j.1469-7610.2007.01741.x
13. Flom, M., & Saudino, K. J. (2017). Callous–unemotional behaviors in early childhood: Genetic and environmental contributions to stability and change. Development and Psychopathology, 29(4), 1227–1234. doi: 10.1017/S0954579416001267
14. Gregory, A. M., Light‐Häusermann, J. H., Rijsdijk, F., & Eley, T. C. (2009). Behavioral genetic analyses of prosocial behavior in adolescents. Developmental Science, 12(1), 165–174. doi: 10.1111/j.1467-7687.2008.00739.x
15. Grove, W. M., Eckert, E. D., Heston, L., BouchardJr, T. J., Segal, N., & Lykken, D. T. (1990). Heritability of substance abuse and antisocial behavior: a study of monozygotic twins reared apart. Biological Psychiatry, 27(12), 1293–1304. doi: 10.1016/0006-3223(90)90500-2.
16. Henry, J., Dionne, G., Viding, E., Petitclerc, A., Feng, B., Vitaro, F., ... & Boivin, M. (2018). A longitudinal twin study of callous-unemotional traits during childhood. Journal of Abnormal Psychology, 127(4), 374–384. doi: 10.1037/abn0000349.
17. Hoekstra, C., Zhao, Z. Z., Lambalk, C. B., Willemsen, G., Martin, N. G., Boomsma, D. I., & Montgomery, G. W. (2007). Dizygotic twinning. Human Reproduction Update, 14(1), 37–47. doi: 10.1093/humupd/dmm036
18. Joseph, J. (1998). The equal environment assumption of the classical twin method: A critical analysis. The Journal of Mind and Behavior, 19(3), 325–358.
19. Joseph, J. (2002). Twin studies in psychiatry and psychology: Science or pseudoscience?. Psychiatric Quarterly, 73(1), 71–82. doi: 0033-2720/02/0300-0071/0.
20. Kaprio, J., Koskenvuo, M., & Langinvainio, H. (1984). Finnish twins reared apart. IV: Smoking and drinking habits. A preliminary analysis of the effect of heredity and environment. Acta Geneticae Medicae et Gemellologiae: Twin Research, 33(3), 425–433.
21. Klein, B. (2003). Not all twins are alike: Psychological profiles of twinship. Westport: Greenwood Publishing Group.
22. Klein, B. (2012). Alone in the mirror: Twins in therapy. New York: Routledge Taylor & Francis Group.
23. Larsson, J. O., Larsson, H., & Lichtenstein, P. (2004). Genetic and environmental contributions to stability and change of ADHD symptoms between 8 and 13 years of age: A longitudinal twin study. Journal of the American Academy of Child and Adolescent Psychiatry, 43(10), 1267– 1275. doi: https://doi.org/10.1097/01.chi.0000135622.05219.bf
24. Loehlin, J. C., & Nichols, R. C. (2012). Heredity, Environment, and Personality: A study of 850 sets of twins. Texas: University of Texas Press.
25. Lykken, D. T. (1982). Research with twins: The concept of emergenesis. Psychophysiology, 19(4), 361– 372.
26. Lykken, D. T., McGue, M., & Tellegen, A. (1987). Recruitment bias in twin research: The rule of two- thirds reconsidered. Behavior Genetics, 17(4), 343–362.
27. McAdams, T. A., Hannigan, L. J., Eilertsen, E. M., Gjerde, L. C., Ystrom, E., & Rijsdijk, F. V. (2018). Revisiting the children-of-twins design: improving existing models for the exploration of intergenerational associations. Behavior Genetics, 48(5), 397–412. doi: 10.1007/s10519-018- 9912-4.
28. Pedersen, N. L., Friberg, L., Floderus-Myrhed, B., McClearn, G. E., & Plomin, R. (1984). Swedish early separated twins: Identification and characterization. Acta Geneticae Medicae et Gemellologiae: Twin Research, 33(2), 243–250.
29. Plomin, R. (2004). Genetics and developmental psychology. Merrill-Palmer Quarterly, 50(3), 341–352.
30. Plomin, R., Asbury, K., & Dunn, J. (2001). Why are children in the same family so different? Non shared environment a decade later. The Canadian Journal of Psychiatry, 46(3), 225–233. doi: 10.1177/070674370104600302
31. Plomin, R., DeFries, J. C., McClearn, G. E, & McGuffin, P. (2001). Behavioral genetics (4. ed.). New York: Worth.
32. Reiss, D. (1997). Mechanisms linking genetic and social influences in adolescent development: Beginning a collaborative search. Current Directions in Psychological Science, 6(4), 100–105.
33. Rowe, D. C. (1994). The limits of family influence: Genes, experience, and behavior. New York: Guilford Press,
34. Rushton, J. P. (1990). Sir Francis Galton, epigenetic rules, genetic similarity theory, and human life‐history analysis. Journal of Personality, 58(1), 117–140.
35. Sahu, M., & Prasuna, J. G. (2016). Twin studies: A unique epidemiological tool. Indian Journal of Community Medicine: Official Publication of Indian Association of Preventive and Social Medicine, 41(3), 177–182. doi: 10.4103/0970-0218.183593
36. Saunders, G. R., Elkins, I. J., Christensen, K., & McGue, M. (2018). The relationship between subjective well-being and mortality within discordant twin pairs from two independent samples. Psychology and Aging, 33(3), 439–447. doi: 10.1037/pag0000248
37. Scarr, S., & McCartney, K. (1983). How people make their own environments: A theory of genotype-environment effects. Child Development, 54(2), 424–435.
38. Segal, N. L. (1990). The importance of twin studies for individual differences research. Journal of Counseling and Development, 68(6), 612–622.
39. Segal, N. L. (2010). Twins: The finest natural experiment. Personality and Individual Differences, 49(4), 317–323. doi: 10.1016/j.paid.2009.11.014
40. Segal, N. L. (2012). Born Together—Reared Apart: The Landmark Minnesota Twin Study. Massauchusetts: Harvard University Press.
41. Segal, N. L. (2017). Twin myth conceptions: False beliefs, fables, and facts about twins. London: Academic Press.
42. Segal, N. L., Montoya, Y. S., Loke, Y. J., & Craig, J. M. (2017). Identical twins doubly exchanged at birth: A case report of genetic and environmental influences on the adult epigenome. Epigenomics, 9(1), 5–12. doi: 10.2217/epi-2016-0104
43. Segal, N. L., Weisfeld, G. E., & Weisfeld, C. C. (1997). Uniting psychology and biology: Integrative perspectives on human development. Washington: American Psychological Association.
44. Sharma, K. (2005). Genetic epidemiology of epilepsy: A twin study. Neurology India, 53(1), 93–98. doi: 10.4103/0028-3886.15070
45. Thapar, A., Pine, D. S., Leckman, J. F., Scott, S., Snowling, M. J., & Taylor, E. (2015). Rutter’s child and adolescent psychiatry (6. ed.). Chichester: Wiley.
46. TÜİK, (2016). Doğum İstatistikleri. 10.12.2018 tarihinde http://www.tuik.gov.tr/basinOdasi/haberler/2016_53_20160427.pdf adresinden erişildi.
47. Whitam, F. L., Diamond, M., & Martin, J. (1993). Homosexual orientation in twins: A report on 61 pairs and three triplet sets. Archives of Sexual Behavior, 22(3), 187–206.
48. Wilson, R. S. (1983). The Louisville twin study: Developmental synchronies in behavior. Child Development, 54(2), 298–316.
49. Wright, L. (1997).Twins and what they tell us about who we are. New York: John. Wiley & Sons.
50. Zazzo, R. (1977). Genesis and peculiarities of the personality of twins. Twin Research Proceedings of the Second International Congress on Twin Studies. September 1, 1977, Washington, DC.