The following is a summary of “Testing quantitative and qualitative sex effects in a national swedish twin-sibling study of posttraumatic stress disorder,” published in the June 2024 issue of Psychiatry by Amstadter et al.
Twin studies show that posttraumatic stress disorder (PTSD) is moderately heritable, possibly more so in females than males. However, formal sex difference testing in PTSD heritability hasn’t been done yet.
Researchers conducted a retrospective study estimating genetic and environmental influences on PTSD and tested for sex differences in a large sample of twins and siblings.
They used the Swedish National Registries and structural equation modeling to analyze genetic and environmental factors for PTSD. The study included 16,242 twin pairs and 376,093 sibling pairs (within 2 years of age), using diagnostic codes from medical records to test for sex differences.
The results showed that the best-fit model indicated that both genetics and unique environment influence PTSD. Females showed higher heritability (35.4%) than males (28.6%). A strong genetic correlation between sexes (rg=0.81, 95% CI= 0.73-0.89), but no shared or special twin environment effects were observed.
Investigators concluded that the first evidence of quantitative and qualitative sex effects on PTSD indicated stronger genetic influences in females than in males. A unique environment, not shared, contributes to PTSD. Although highly correlated, genetic influences differ between sexes.
Source: psychiatryonline.org/doi/10.1176/appi.ajp.20230104
