title: Commentary: How can family-based quasi-experimental designs and national registers be used to address confounding in risk factor studies of psychopathology? A reflection on Obel et al. (2016).
abstract: Standard observational studies have reported a robust correlation between maternal smoking during pregnancy and risk of ADHD in offspring. In the accompanying article, Obel et al. used sibling-comparisons to explore the extent to which unmeasured familial confounding explains this association. This commentary highlights three important implications of the study. At a general level, Obel et al. illustrates how (1) family-based quasi-experimental designs and (2) national registers can be used to address confounding in risk factor studies of psychopathology. At a more specific level, the study suggests that maternal smoking during pregnancy is probably not a causal risk factor for ADHD.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Larsson
mesh_terms: D006801:Humans; D011297:Prenatal Exposure Delayed Effects; D016016:Proportional Hazards Models; D011599:Psychopathology; D012107:Research Design; D012307:Risk Factors; D012907:Smoking
keywords: Risk factors; familial confounding; maternal smoking; sibling-comparisons; smoking during pregnancy