Age at first intoxication and alcohol use disorders in southwest California Indians

Background: In several national surveys, a younger age of onset of first drink and/or regular drinking has been associated with a higher likelihood of the development of alcohol dependence. Some studies have suggested that age at first drink is primarily an environmentally driven variable whereas others suggest that it may be partially mediated by a general vulnerability to exhibit problem behaviors. Although Native Americans, overall, have the highest prevalence of alcohol dependence of any U.S. ethnic group, the relationship of age of onset of intoxication with alcohol dependence in Native American populations is relatively unknown. Methods: Demographic information and DSM-III-R diagnoses were obtained from 525 Southwest California (SWC) Indian adults residing on contiguous reservations. Survival analyses and Cox and logistic regression were used to investigate the relationship between age of onset of first intoxication and the development of alcohol dependence. Heritability of the age of onset of first intoxication was also determined using SOLAR. Results: Age at first intoxication was not found to be heritable in this population. Early onset of intoxication, however, was found to be significantly associated with both a shorter time to onset of alcohol dependence and increased prevalence in this population, even on taking into account several other risk factors including externalizing diagnoses. Conclusions: These data suggest that effective environmental prevention efforts at reducing underage drinking may be an important strategy to lower the prevalence of alcohol dependence in this high-risk population.