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- Hettema, John M., et al.
(författare)
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The genetic covariation between fear conditioning and self-report fears
- 2008
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Ingår i: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 63:6, s. 587-593
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Tidskriftsartikel (refereegranskat)abstract
- Background: Fear conditioning is a traditional model for the acquisition of phobias, whereas behavioral therapies use processes underlying extinction to treat phobic and other anxiety disorders. Furthermore, fear conditioning has been proposed as an endophenotype for genetic studies of anxiety disorders. Although prior studies have demonstrated that fear conditioning and self-report fears are heritable, no studies have determined whether they share a common genetic basis. Methods: We obtained fear conditioning data from 173 twin pairs from the Swedish Twin Registry who also provided self-report ratings of 16 common fears. With multivariate structural equation modeling, we analyzed factor-derived scores for the subjective fear ratings together with the electrophysiologic skin conductance responses during habituation, acquisition, and extinction to determine the extent of their genetic covariation. Results: Phenotypic correlations between experimental and self-report fear measures were modest and, counter-intuitively, negative (i.e., subjects who reported themselves as more fearful had smaller electrophysiologic responses). Best-fit models estimated a significant (negative) genetic correlation between them, although genetic factors underlying fear conditioning accounted for only 9% of individual differences in self-report fears. Conclusions: Experimentally derived fear conditioning measures share only a small portion of the genetic factors underlying individual differences in subjective fears, cautioning against relying too heavily on the former as an endophenotype for genetic studies of phobic disorders.
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| 2. |
- Kendler, Kenneth S., et al.
(författare)
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A longitudinal twin study of fears from middle childhood to early adulthood : evidence for a developmentally dynamic genome
- 2008
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Ingår i: Archives of General Psychiatry. - : American Medical Association (AMA). - 0003-990X .- 1538-3636. ; 65:4, s. 421-429
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Tidskriftsartikel (refereegranskat)abstract
- Context: While the nature of common fears changes over development, we do not know whether genetic effects on fear-proneness are developmentally stable or developmentally dynamic. Objective: To determine the temporal pattern of genetic and environmental effects on the level of intensity of common fears. Design: Prospective, 4-wave longitudinal twin study. Structural modeling was performed with Mx. Setting: General community. Participants: Two thousand four hundred ninety twins and their parents from the Swedish Twin Study of Child and Adolescent Development. Main Outcome Measure: The level of parent- and/or self-reported fears obtained at ages 8 to 9, 13 to 14, 16 to 17, and 19 to 20 years. Results: Thirteen questionnaire items formed 3 distinct fear factors: situational, animal, and blood/injury. For all 3 fears, the best-fit model revealed developmentally dynamic effects and, in particular, evidence for both genetic attenuation and innovation. That is, genetic factors influencing fear intensity at age 8 to 9 years decline substantially in importance over time. Furthermore, new sets of genetic risk factors impacting fear intensity "come on line" in early adolescence, late adolescence, and early adulthood. As the twins aged, the influence of the shared environment declined and unique environment increased. No sex effects were found for situational fears while for animal and blood/injury fears, genetic factors in males and females were correlated but not identical. Shared environmental factors were both more important and,more stable for animal fears than for situational or blood/injury fears. Conclusions: Genetic effects on fear are developmentally dynamic from middle childhood to young adulthood. As children age, familial-environmental influences on fears decline in importance.
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