Don't throw away the champagne with the cork-age at first drink revisited

A Co-Twin Control Study of the Relationship Between Adolescent Drinking and Adult Outcomes

OBJECTIVE

The effect of drinking during adolescence on adult functioning is a public health concern. A variety of mechanisms have been proposed where drinking in adolescence has an adverse impact on later outcomes; unfortunately, few studies have included methodologies that account for confounding influences that might link adolescent drinking with subsequent problems. To address this limitation, the current study used a co-twin control design, which uses members of twin pairs that differ from each other on their adolescent drinking.

METHOD

We used a prospective longitudinal sample drawn from the Minnesota Twin Family Study, consisting of 2,764 twins (1,434 female) assessed at regular follow-ups from age 17 to age 29. Adolescent drinking was defined by measures of early initiation of use and a measure of overall consumption at age 17. Adult outcomes included indicators of substance use, antisocial behavior, personality, socioeconomic status, and social functioning.

RESULTS

The co-twin control analyses suggested that many of the associations between adolescent drinking and later outcomes were largely influenced by genetic confounding. However, for the measure of adolescent alcohol consumption, results were consistent with a small causal impact of drinking on multiple domains of adult functioning. This pattern was less consistently observed for the measures of early initiation.

CONCLUSIONS

These results provide empirical justification for policies designed to alleviate long-term consequences associated with adolescent drinking by reducing the level of alcohol consumption in adolescence. In contrast, the evidence did not suggest that delaying drinking would have a broad impact on later-life adjustment.

Childhood cigarette and alcohol use: Negative links with adjustment

Children who initiate cigarette or alcohol use early-during childhood or early adolescence-experience a heightened risk of nicotine and alcohol dependence in later life as well as school failure, crime, injury, and mortality. Using prospective intergenerational data from the Millennium Cohort Study (MCS), we investigate the association between early substance use initiation (cigarettes or alcohol) and age 11 school engagement, academic achievement, and wellbeing. The ongoing MCS tracks the development of a nationally representative sample of children in the United Kingdom (born 2000-2002) from infancy through adolescence. At age 11, MCS children (n=13,221) indicated whether they had ever used cigarettes or alcohol; at age 7 and 11 they reported on school engagement and wellbeing and completed investigator-assessed tests of academic achievement. Using propensity score methods, children who had initiated cigarette or alcohol use by age 11 were matched to abstaining children with similar risks (or propensities) of early substance use, based on numerous early life risk and protective factors assessed from infancy to age 7. We then examined whether early initiators differed from non-initiators in age 11 adjustment and achievement. Results show that substance use by age 11 was uncommon (3% cigarettes; 13% alcohol). After matching for propensity for early initiation, school engagement and wellbeing were significantly lower among initiators compared to non-initiators. Academic achievement was not consistently related to early initiation. We conclude that initiation of smoking and drinking in childhood is associated with poorer adjustment.