In Model I, Group 1 and Group 2 offspring were at 20% and 30% increased hazards of transitioning from alcohol use to an AD problem respectively, compared to Group 4 (see Table 3). Risk to offspring whose DZ uncle was AD (Group 3b) was significantly increased compared to Group 4 as well (HR=1.36). In post-hoc tests, Group 2 (MZ uncle DD/AD) and Group 3b (DZ uncle AD) also had an increased hazard for alcohol initiation compared to Group 3a (dad unaffected, MZ uncle DD). The effects of risk group in Models II and III were nearly identical to those in Model I in both magnitude and significance, except that Groups 3a and 3b were not significantly different from each other and could be combined into a single “DZ uncle DD/AD” group. Whereas in Model II the effect of parental separation on timing of first AD symptom was non-significant, in Model III a protective effect was observed, with parental separation predicting a 19% decreased hazard of transitioning to any AD symptom. Interactions between father DD/AD and parental separation were tested by adding an interaction term to Models II and III; no interaction terms were significant (p > 0.05).
