Women Show Higher Genetic Predisposition to PTSD: Daily Dose

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On December 19, 2024, we reported on findings from a study published in the American Journal of Psychiatry that estimated the genetic and environmental contributions to post-traumatic stress disorder (PTSD) and examined quantitative and qualitative sex differences.

The study

Tapping the Swedish National Registries for anonymized data, researchers assembled the largest known sample to date of both sexes among twins (N = 16 242 pairs) and siblings (N = 376 093 pairs). Using registry data, they explained, removes the potential bias of self-report or interviews and extending the analysis to sibling pairs allowed investigators to test for an influence of twin-specific environment in PTSD etiology.

The findings

The best-fit model suggested that additive genetic and unique environmental effects, but not the shared environment, contributed to PTSD, according to the results.

The investigators found evidence for a quantitative sex effect, reporting heritability among women (35.4%) that was 7 points higher than among men (28.6%). The evidence for a qualitative sex effect was highly correlated (0.81) but not complete between the sexes.

Authors' comments

"Given the high comorbidity of PTSD with other disorders across the internalizing and externalizing spectrum, future analyses should incorporate multivariate modeling to test the degree of heritable overlap between PTSD and other common posttraumatic conditions. In addition, replication of findings with diverse ancestries is needed."

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