A later report by this group evaluated the finding of an association of AFD with chronicity of dependence in a subset of 706 people in the same cohort in greater detail after splitting the exposure into AFD before age 11 years or not.21 This study extension was principally concerned to test three competing hypotheses for the association between AFD and chronicity of dependence using mediation analyses in structural equation regression models. These hypotheses related to: confounding by other risk factors (the marker hypothesis, see later); developmental impairment leading to greater involvement with alcohol; and increased adolescent substance use. None of these hypotheses were supported.21
