Abstract
This study examined the extent to which the genetic and environmental characteristics of having a first versus a second suicide attempt (SA) are common or specific. We evaluated the direct pathway between these phenotypes and the role of specific risk factors. From Swedish national registries, two subsamples of individuals born between 1960 and 1980 were selected (1,227,287 twin-sibling pairs and 2,265,796 unrelated individuals). First, a twin-sibling model was fit to evaluate the genetic and environmental risk factors related to first and second SA. The model also included a direct path between first and second SA. Second, an extended Cox proportional hazards model (PWP) was used to evaluate the risk factors related to first versus second SA. In the twin-sibling model, suicide reattempt was strongly related to first SA (β = 0.72). The total heritability for the second SA was estimated at 0.48, with 45.80% unique to this second SA. The total environmental influence for the second SA was 0.51, with 50.59% unique. In the PWP model, we found that childhood environment, psychiatric disorders, and selected stressful life events were related to both first and second SA, potentially reflecting common genetic and environmental factors. Other stressful life events were associated with first but not second SA in the multivariable model, suggesting their specificity in explaining the first occurrence of SA but not its recurrence. Specific risk factors related to second SA need to be further explored. These findings have important implications for describing the pathways toward suicidal behavior and identifying individuals at risk for multiple SA. (PsycInfo Database Record (c) 2023 APA, all rights reserved).