Background: The low level of response (LR) to alcohol is related to a family history (FH) of alcohol use disorders (AUDs), and each predicts alcohol-related outcomes. Few studies have evaluated the interrelationships between the number of alcoholic relatives, LR, and a range of alcohol-related outcomes. This study tests the hypotheses that there will be an inverse relationship between LR and FH and that LR will be a better predictor of the maximum quantity of alcohol consumed.
Methods: Data were extracted from personal interviews with 376 males from 20 years of follow-up in the San Diego Prospective Study. Level of response had been established at about age 20 through alcohol challenges in this population, about half of whom had at least one alcoholic relative. Face-to-face follow-ups with both the subjects and additional informants were carried out 10, 15, and 20 years later. These analyses used correlations and regressions to evaluate the relationship between the 2 major predictors (FH and LR) and 5 alcohol-related outcomes over 20 years of follow-up.
Results: As predicted, the alcohol challenge-based LR correlated significantly with the number of alcoholic relatives (up to -0.17 for subjects with clearly high and low LR scores). Each of the 2 predictors correlated with the 5 outcomes, including the maximum quantity of alcohol consumed since original testing, maximum frequency, nondiagnostic alcohol-related problems, the number of 11 DSM-IV (Fourth Diagnostic and Statistical Manual of Mental Disorders) abuse and dependence items, and having developed alcohol abuse or dependence. In hierarchical regression analyses, LR contributed significantly to the prediction of all 5 outcomes, even when considered in the context of FH, with only LR predicting drinking quantity and frequency, but both items adding to the prediction of alcohol-related problems and diagnoses. These results were not affected by the intensity of usual drinking when LR had been measured at age 20.
Conclusions: Both FH and LR contributed to a range of alcohol-related outcomes, with LR alone significantly predicting maximum quantity and frequency in regression analyses.