Causal Influence of Age at First Drink on Alcohol Involvement in Adulthood and Its Moderation by Familial Context

Abstract

ABSTRACT. Objective: Previous research has established a connection between early age at drinking initiation and greater alcohol involvement in adulthood, but it has not yet been established whether this is a causal effect. The current study used a multilevel discordant twin design to examine individual and contextual effects, and an interaction between these effects, of the age at drinking initiation on the frequency and quantity of drinking in adulthood. Method: Participants were 4,194 same-sex twins (2,264 monozygotic, 1,924 dizygotic; 2,270 women; M age = 29.9 years) from the Australian Twin Registry who completed a telephone interview that included assessments of the age at alcohol use initiation and past-year frequency and quantity of alcohol use. Multilevel models were estimated using data from the full sample and using data from only monozygotic twins. Individual (within-twin-pair comparison) and family contextual (between-twin-pair comparison) effects were estimated. Results: The age at fi rst drink was related to the past-year frequency (r = -.16) and quantity of drinking (r = -.12) in young adulthood. Individual (causal) and family context effects of age at drinking onset predicted later adult drinking frequency and quantity. There was also a signifi cant cross-level interaction between individual and family contexts for frequency but not quantity of drinking. Conclusions: Results of this study indicate a potential causal effect of age at drinking onset on adult alcohol involvement as well as the importance of examining both individual and contextual effects in discordant twin studies. (J. Stud. Alcohol Drugs, 74, 703-713, 2013)

Tests of the effects of adolescent early alcohol exposures on adult outcomes

“…Earlier twin pair analysis had suggested that the association between age at first drink and later development of alcohol dependence was non-causal and likely attributable largely to common genetic effects [9]. However, more recent studies using CTC have found that the relationship between earlier alcohol use and measures of adult alcohol involvement [18], adult alcohol dependence, and the use and abuse of other substances [19], may not be entirely attributable to familial factors shared between twins. Instead, they are likely to also be significantly, though less strongly, influenced by factors not shared by twins discordant for early alcohol use or age at first drink.…”

Test of a potential causal influence of earlier age of gambling initiation on gambling involvement and disorder: A multilevel discordant twin design.

“…An important distinction is between causal and non-causal mechanisms. In a previous paper, we applied multilevel modeling of data from twin pairs to adjudicate between causal and non-causal mechanisms in explaining the inverse relation between the age of drinking initiation and the frequency and quantity of alcohol use in early adulthood (Deutsch et al, 2013). Effects at the individual level, family level, and their interaction explained the inverse relation between the age of alcohol use initiation and adult alcohol involvement.…”

Developmental Etiologies of Alcohol Use and Their Relations to Parent and Peer Influences Over Adolescence and Young Adulthood: A Genetically Informed Approach

“…Future research may benefit from examining adolescent-specific environments relating to drinking behavior. Research indicates that early adolescent alcohol use is a possibly causal risk factor for higher adulthood alcohol (e.g., Deutsch et al, 2013; Deutsch et al, 2016). Extreme risk factors linked to high levels of alcohol use that exclusively occur in childhood and adolescence (e.g., child abuse, Dube et al, 2006; parental divorce, Sartor, Lynskey, Heath, Jacob & True, 2007), may account for environmental variance related to alcohol use.…”