Teenagers who abuse alcohol are more likely to make a rocky transition into early adulthood, according to a large study of twins.
After analyzing longitudinal data on more than 3,000 twins, researchers at Indiana University focused on adolescent twins who were “drinking-discordant” — in other words, one drank and the other did not.
“Very few studies that control for expected influences of shared familial experience and shared genetic liabilities on drinking outcomes have been reported," said Richard Rose, professor emeritus in psychology and brain science at Indiana University.
Researchers associated drinking problems at age 18.5 years of age with 13 outcomes, including substance abuse, poor health, physical symptoms, early onset of sexual activity, multiple sexual partners, life dissatisfaction, financial problems, and a lack of education.
Results showed that individual twins who previously had drinking problems at age 18.5 had more adverse outcomes for all 13 measures at age 25, and many of these associations replicated within discordant co-twins. "Because we studied drinking-discordant twin pairs, our results rule out between-family confounds as the sole source of the association of adolescent drinking problems with adverse adult outcomes," said Rose.
Rose says the study at least eliminates some confusion from the mix. “To my knowledge, ours is the first prospective study of discordant twin pairs,” Rose said. “It is, accordingly, the first to evaluate whether the established association of adolescent drinking problems with adverse adult outcomes can be fully explained by shared genetic and environmental liabilities. Our data suggest not."
The study was published in Alcoholism: Clinical and Experimental Research.