Etiological Development of Alcohol Use and Dependence From Adolescence to Midlife in a Longitudinal Community Study of Twins.

BACKGROUND

Alcohol use disorder (AUD) criteria emphasize physiological and psychological consequences of alcohol use without direct evaluation of quantity and frequency of consumption. It remains unclear whether alcohol dependence is an extreme outcome on the alcohol use spectrum or if it represents a separate pattern of behavior with different genetic and environmental influences. To investigate this, we evaluated relationships between alcohol consumption and dependence from adolescence to middle age in a large twin sample.

METHODS

Participants were twins (monozygotic pairs = 1205, dizygotic pairs = 676; 52% female) assessed at six waves from adolescence into midlife (age range = 13.6-49.4 years) on frequency of alcohol use, quantity of use, and dependence/abuse symptoms. At each assessment, we fit a longitudinal factor model with a single latent factor loading onto the three alcohol measures. Common and specific factor variance was decomposed into genetic and environmental components.

RESULTS

Alcohol use frequency peaked in early adulthood and remained stable; alcohol use quantity and dependence symptoms peaked in early adulthood and declined thereafter. Factor loadings within waves could not be constrained to be equal at all timepoints without significant detriment to model fit (increases in AIC = 1149 and BIC = 1081). Models constraining loadings at individual timepoints indicate that the measures can be reasonably equated at ages 24 and 29 (decreases in BIC = 3.1 and 2.9, respectively). Genetic factors accounted for about 50% of variance in the latent alcohol behavior factor from ages 14 through 29 but decreased (p = 0.007) to 24% by age 37.

CONCLUSIONS

Alcohol use and dependence are distinct in adolescence and young adulthood but show convergence in adulthood, such that alcohol dependence symptom count does not clearly measure a construct separate from alcohol consumption longitudinally. These developmental shifts have clinical implications, with AUD screening reliant on assessment of alcohol use patterns expected to perform more reliably in adults than adolescents.