title: Psychological strength assessed in late adolescence and risk for criminal behavior: a Swedish prospective cohort and twin analysis.
abstract: BACKGROUND
  Certain personality traits predispose to criminal behavior (CB). We further clarify this relationship in a Swedish national sample.
  
  
  METHODS
  Psychological strength (PS) was assessed on a nine-point scale at personal interview in 1 653 721 Swedish men aged 18-20 years. We examined the association between PS and total, violent and recurrent CB over the lifetime (logistic regression), prospectively (Cox regression) and by bivariate Cholesky decomposition in 2507 monozygotic and 2244 dizygotic twin pairs (OpenMx).
  
  
  RESULTS
  Examining linear effects by logistic regression, PS was robustly associated with lifetime risk of total CB (per point, odds ratio = 0.74) and even more strongly associated with risk for violent (0.69) and recurrent CB (0.52). Prospective predictions of these three forms of CB by PS were similar, with hazard ratios of 0.80, 0.73 and 0.54, respectively. Twin modeling demonstrated that, for all three CB types, the association with PS arose almost entirely from familial effects. Common shared environment accounted for 72, 56 and 43% of the phenotypic correlation between PS and, respectively, total, violent and recurrent CB. Parallel figures for common genetic effects were for 24, 37 and 54%, respectively.
  
  
  CONCLUSIONS
  PS is strongly related to risk for total CB, and even more strongly for violent and, especially, recurrent CB. This association is probably not causal but rather results from shared familial risk factors that make an impact both on PS and risk for CB. PS has a stronger overall correlation with more severe criminal outcomes and a higher proportion of that correlation results from common genetic factors.
authors.affiliation: Virginia Institute for Psychiatric and Behavioral Genetics,Virginia Commonwealth University,Richmond,VA,USA.
authors.forename: K S
authors.initials: KS
authors.lastname: Kendler
authors.affiliation: Center for Primary Health Care Research,Lund University,Malmö,Sweden.
authors.forename: S L
authors.initials: SL
authors.lastname: Lönn
authors.affiliation: Department of Medical Epidemiology and Biostatistics,Karolinska Institute,Stockholm,Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Lichtenstein
authors.affiliation: Center for Primary Health Care Research,Lund University,Malmö,Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Sundquist
authors.affiliation: Center for Primary Health Care Research,Lund University,Malmö,Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Sundquist
mesh_terms: D000293:Adolescent; D000328:Adult; D000066479:Criminal Behavior / Q000502:physiology*; D006801:Humans; D008297:Male; D010551:Personality / Q000502:physiology*; D011446:Prospective Studies; D012042:Registries / Q000706:statistics & numerical data*; D055500:Resilience, Psychological; D012306:Risk; D013548:Sweden; D014754:Violence / Q000706:statistics & numerical data*; D055815:Young Adult
keywords: Crime; personality; twins; violence