title: From alcohol initiation to tolerance to problems: Discordant twin modeling of a developmental process.
abstract: The current study examined a stage-based alcohol use trajectory model to test for potential causal effects of earlier drinking milestones on later drinking milestones in a combined sample of two cohorts of Australian monozygotic and same-sex dizygotic twins (N = 7,398, age M = 30.46, SD = 2.61, 61% male, 56% monozygotic twins). Ages of drinking, drunkenness, regular drinking, tolerance, first nontolerance alcohol use disorder symptom, and alcohol use disorder symptom onsets were assessed retrospectively. Ages of milestone attainment (i.e., age-of-onset) and time between milestones (i.e., time-to-event) were examined via frailty models within a multilevel discordant twin design. For age-of-onset models, earlier ages of onset of antecedent drinking milestones increased hazards for earlier ages of onset for more proximal subsequent drinking milestones. For the time-to-event models, however, earlier ages of onset for the "starting" milestone decreased risk for a shorter time period between the starting and the "ending" milestone. Earlier age of onset of intermediate milestones between starting and ending drinking milestones had the opposite effect, increasing risk for a shorter time period between the starting and ending milestones. These results are consistent with a causal effect of an earlier age of drinking milestone onset on temporally proximal subsequent drinking milestones.
authors.affiliation: University of Missouri-Columbia.
authors.forename: Arielle R
authors.initials: AR
authors.lastname: Deutsch
authors.affiliation: University of Missouri-Columbia.
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Slutske
authors.affiliation: Washington University School of Medicine.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lynskey
authors.affiliation: Washington University School of Medicine.
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Bucholz
authors.affiliation: Washington University School of Medicine.
authors.forename: Pamela A F
authors.initials: PAF
authors.lastname: Madden
authors.affiliation: Washington University School of Medicine.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Heath
authors.affiliation: QIMR Berghofer Medical Research Institute.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Martin
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000428:Alcohol Drinking / Q000235:genetics*; D000435:Alcoholic Intoxication / Q000235:genetics*; D000437:Alcoholism / Q000235:genetics*; D001315:Australia; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D055815:Young Adult