Longitudinal stability and change in consumption among female twins: Contributions of genetics

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Abstract
Problem alcohol use among women is increasingly recognized as an important public health and mental health issue. Younger women appear to be at increased risk for heavy drinking and alcohol-related problems compared to women from earlier cohorts. Understanding the sources for inter- and intra-individual differences in alcohol consumption is an important first step in addressing these trends. We studied the sources underlying variation in alcohol consumption in a sample of 2,163 female twins born in Virginia between 1934 and 1970. Measures of past-year alcohol consumption quantity and frequency were obtained on two occasions across a 5-year interval. Quantity and frequency of consumption declined over age, both cross-sectionally and longitudinally. Intra-individual correlations over the interval were substantial for frequency of drinking (r = .62) and quantity consumed per drinking occasion (r = .56) but lower for quantity consumed weekly (r = .22). There was significant intrapair resemblance for all measures, with the drinking behavior of identical twin pairs being more similar than that of fraternal pairs. Twin analyses of patterns of change in consumption over a 5-year interval revealed little within-pair similarity in rate of change, with correlations ranging from .06 to .18, suggesting that among young adult to middle-aged women, determinants of changing alcohol consumption are largely individual-specific. There was some evidence for significant age interactions, with the role of individual-specific sources increasing over age.