K S Kendler1, H Ohlsson2, K Sundquist2, J Sundquist2. 1. Virginia Institute for Psychiatric and Behavioral Genetics,Virginia Commonwealth University,Richmond, VA,USA. 2. Center for Primary Health Care Research,Lund University,Malmö,Sweden.
Abstract
BACKGROUND: While drug abuse (DA) is strongly familial, we still have limited knowledge about the causes of its cross-generational transmission. METHOD: We examined DA ascertained from national registers in offspring of three family types from the Swedish population [intact (n = 2,111,074), 'not-lived-with' (n = 165,315, where biological parents never lived with their offspring) and 'step' (n = 124,800 offspring)], which reflected, respectively, the effects of genes + rearing, genes only and rearing only. We replicated these results in three high-risk co-relative designs. RESULTS: Combined across mothers and fathers, the hazard ratio (HR) for DA in offspring given DA in parents was 3.52 in intact, 2.73 in 'not-lived-with' and 1.79 in stepfamilies. In 968 biological full or half-sibling pairs one of whom was reared by and the other never lived with their parent with DA, the HR for DA was greater in the reared than 'not-lived-with' child (HR 1.57). In 64 offspring pairs of a parent with DA, the HR for DA was greater in a reared biological v. step-parented non-biological child (HR 3.33). In 321 pairs of offspring of a parent with DA one of whom was a not-lived-with biological child and the second a step-parented non-biological child, the HR for DA was greater in the biological v. stepchild (HR 1.80). CONCLUSIONS: Both genetic and environmental factors contribute substantially to parent-offspring resemblance for DA. The general population contains informative family constellations that can complement more traditional adoption designs in clarifying the sources of parent-offspring resemblance.
BACKGROUND: While drug abuse (DA) is strongly familial, we still have limited knowledge about the causes of its cross-generational transmission. METHOD: We examined DA ascertained from national registers in offspring of three family types from the Swedish population [intact (n = 2,111,074), 'not-lived-with' (n = 165,315, where biological parents never lived with their offspring) and 'step' (n = 124,800 offspring)], which reflected, respectively, the effects of genes + rearing, genes only and rearing only. We replicated these results in three high-risk co-relative designs. RESULTS: Combined across mothers and fathers, the hazard ratio (HR) for DA in offspring given DA in parents was 3.52 in intact, 2.73 in 'not-lived-with' and 1.79 in stepfamilies. In 968 biological full or half-sibling pairs one of whom was reared by and the other never lived with their parent with DA, the HR for DA was greater in the reared than 'not-lived-with' child (HR 1.57). In 64 offspring pairs of a parent with DA, the HR for DA was greater in a reared biological v. step-parented non-biological child (HR 3.33). In 321 pairs of offspring of a parent with DA one of whom was a not-lived-with biological child and the second a step-parented non-biological child, the HR for DA was greater in the biological v. stepchild (HR 1.80). CONCLUSIONS: Both genetic and environmental factors contribute substantially to parent-offspring resemblance for DA. The general population contains informative family constellations that can complement more traditional adoption designs in clarifying the sources of parent-offspring resemblance.
Authors: Kenneth S Kendler; Hermine H Maes; Kristina Sundquist; Henrik Ohlsson; Jan Sundquist Journal: Am J Psychiatry Date: 2014-02 Impact factor: 18.112
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