Longitudinal Associations of Childhood Internalizing Psychopathology With Substance Misuse: A Register-Based Twin and Sibling Study

Objective The pathways from internalizing psychopathology to substance misuse remain largely unclear. We estimated associations between childhood problems and subsequent in 2 family-based samples. also investigated sex differences the role of externalizing comorbidity. Method studied with register-based after age 13 years. Sample 1 included all individuals born Sweden 1984 2000 (N = 1,768,516). Depressive anxiety disorders were as International Classification Diseases Ninth Revision (ICD-9) or Tenth (ICD-10) diagnoses before 13. was a subsample within population sample, Child Adolescent Twin Study (CATSS) twin cohort (n 12,408; 1992–1998), mood assessed at 9/12 by parents. In both samples, defined an ICD-9/10 alcohol/drug use disorder alcohol/drug-related criminal conviction until December 2013. To account for familial effects, stratified analyses conducted siblings pairs. Results depressive (hazard ratio [HR] 2.75, 95% CI 2.36–3.20) (HR 1.52, 1.35–1.73) associated misuse. Childhood 2.28, 1.69–3.08) CATSS sample. partially explained factors, comorbid men but not women. Conclusion misuse, factors shared associations. relationship complex depended on measurement type disorder. Internalizing may be especially important risk