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Testing Quantitative and Qualitative Sex Effects in a National Swedish Twin-Sibling Study of Posttraumatic Stress Disorder

Amstadter, Ananda B. ; Lönn, Sara L. LU ; Cusack, Shannon ; Sundquist, Jan LU ; Kendler, Kenneth S. and Sundquist, Kristina LU (2024) In The American journal of psychiatry 181(8). p.720-727
Abstract

OBJECTIVE: Twin studies have demonstrated that posttraumatic stress disorder (PTSD) is moderately heritable, and the pattern of findings across studies suggests higher heritability in females compared with males. Formal testing of sex differences has yet to be done in twin studies of PTSD. The authors sought to estimate the genetic and environmental contributions to PTSD, and to formally test for sex differences, in the largest sample to date of both sexes, among twins and siblings. METHODS: Using the Swedish National Registries, the authors performed structural equation modeling to decompose genetic and environmental variance for PTSD and to formally test for quantitative and qualitative sex differences in twins (16,242 pairs) and in... (More)

OBJECTIVE: Twin studies have demonstrated that posttraumatic stress disorder (PTSD) is moderately heritable, and the pattern of findings across studies suggests higher heritability in females compared with males. Formal testing of sex differences has yet to be done in twin studies of PTSD. The authors sought to estimate the genetic and environmental contributions to PTSD, and to formally test for sex differences, in the largest sample to date of both sexes, among twins and siblings. METHODS: Using the Swedish National Registries, the authors performed structural equation modeling to decompose genetic and environmental variance for PTSD and to formally test for quantitative and qualitative sex differences in twins (16,242 pairs) and in full siblings within 2 years of age of each other (376,093 pairs), using diagnostic codes from medical registries. RESULTS: The best-fit model suggested that additive genetic and unique environmental effects contributed to PTSD. Evidence for a quantitative sex effect was found, such that heritability was significantly greater in females (35.4%) than males (28.6%). Evidence of a qualitative sex effect was found, such that the genetic correlation was high but less than complete (rg=0.81, 95% CI=0.73-0.89). No evidence of shared environment or special twin environment was found. CONCLUSIONS: This is the first demonstration of quantitative and qualitative sex effects for PTSD. The results suggest that unique environmental effects, but not the shared environment, contributed to PTSD and that genetic influences for the disorder are stronger in females compared with males. Although the heritability is highly correlated, it is not at unity between the sexes.

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Please use this url to cite or link to this publication:
author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Genetics/Genomics, Posttraumatic Stress Disorder (PTSD), Stress
in
The American journal of psychiatry
volume
181
issue
8
pages
8 pages
publisher
American Psychiatric Association
external identifiers
  • pmid:38831706
  • scopus:85200423463
ISSN
1535-7228
DOI
10.1176/appi.ajp.20230104
language
English
LU publication?
yes
id
c1f45465-adbd-47b7-a723-415e16b6b03b
date added to LUP
2024-09-09 13:03:25
date last changed
2024-09-09 13:04:22
@article{c1f45465-adbd-47b7-a723-415e16b6b03b,
  abstract     = {{<p>OBJECTIVE: Twin studies have demonstrated that posttraumatic stress disorder (PTSD) is moderately heritable, and the pattern of findings across studies suggests higher heritability in females compared with males. Formal testing of sex differences has yet to be done in twin studies of PTSD. The authors sought to estimate the genetic and environmental contributions to PTSD, and to formally test for sex differences, in the largest sample to date of both sexes, among twins and siblings. METHODS: Using the Swedish National Registries, the authors performed structural equation modeling to decompose genetic and environmental variance for PTSD and to formally test for quantitative and qualitative sex differences in twins (16,242 pairs) and in full siblings within 2 years of age of each other (376,093 pairs), using diagnostic codes from medical registries. RESULTS: The best-fit model suggested that additive genetic and unique environmental effects contributed to PTSD. Evidence for a quantitative sex effect was found, such that heritability was significantly greater in females (35.4%) than males (28.6%). Evidence of a qualitative sex effect was found, such that the genetic correlation was high but less than complete (rg=0.81, 95% CI=0.73-0.89). No evidence of shared environment or special twin environment was found. CONCLUSIONS: This is the first demonstration of quantitative and qualitative sex effects for PTSD. The results suggest that unique environmental effects, but not the shared environment, contributed to PTSD and that genetic influences for the disorder are stronger in females compared with males. Although the heritability is highly correlated, it is not at unity between the sexes.</p>}},
  author       = {{Amstadter, Ananda B. and Lönn, Sara L. and Cusack, Shannon and Sundquist, Jan and Kendler, Kenneth S. and Sundquist, Kristina}},
  issn         = {{1535-7228}},
  keywords     = {{Genetics/Genomics; Posttraumatic Stress Disorder (PTSD); Stress}},
  language     = {{eng}},
  number       = {{8}},
  pages        = {{720--727}},
  publisher    = {{American Psychiatric Association}},
  series       = {{The American journal of psychiatry}},
  title        = {{Testing Quantitative and Qualitative Sex Effects in a National Swedish Twin-Sibling Study of Posttraumatic Stress Disorder}},
  url          = {{http://dx.doi.org/10.1176/appi.ajp.20230104}},
  doi          = {{10.1176/appi.ajp.20230104}},
  volume       = {{181}},
  year         = {{2024}},
}