This study advances the epidemiology of alcohol dependence by describing the joint effects of educational attainment and race-ethnicity on the risk of alcohol dependence in a large national sample of adults. Progression from alcohol use to dependence was significantly more likely among individuals without a college degree compared to those with a college degree. The risk of dependence did not increase across all levels of education; rather, attainment of a college degree appeared to be a threshold between low and high levels of risk. A similar association between education and current-year alcohol abuse or dependence was observed in the National Comorbidity Survey.20
This association could be attributable to the protective effects of schooling, particularly obtaining a college degree, on the development of alcohol dependence. It may also operate through a broader set of SES pathways including income and occupational status. Our measure of education reflects the individual's socioeconomic background, insofar as opportunities for schooling are influenced by parental resources. As parental SES was not assessed in the NESARC, it was not possible to separate the effects of (exogenous) parental SES from the participants' own (partly endogenous) educational attainment.
A separate component of the association between education and alcohol dependence may operate in the opposite direction: dependence onset before school completion may adversely impact an individual's final educational attainment.21
In the current study, we attempted to isolate the effect of education on subsequent alcohol dependence by modelling education as a time-varying covariate and creating a separate education category (student) for all person-years before school completion. In addition, we conducted analyses which eliminated cases of dependence that occurred while participants were in school. While the contrast between student status and college degree could be contaminated by the reverse effect of alcohol dependence on education, the contrasts between the remaining education categories (≤ high school, GED, some college) and college degree reflect the association between completed education and subsequent risk of dependence onset.
Our findings of lower lifetime rates of alcohol dependence among black, Hispanic and API participants are consistent with previous epidemiological studies,20 22 23
including the National Comorbidity Survey2
and the National Longitudinal Alcohol Epidemiologic Study.24
There is less consistency across previous studies with respect to race-ethnicity differences in current, or 12-month, prevalence of alcohol use disorders. Caetano et al reported higher rates of 12-month dependence symptoms among black people than among white people,25 26
whereas Grant et al
and Kandel et al
reported no such differences.27 28
It is therefore important to distinguish between risks for initial dependence onset and those for the chronicity of dependence. This also implies disaggregating 12-month prevalence into the components that are the result of lifetime risk and those that are the result of the persistence of dependence among lifetime cases.29
One plausible explanation for lower rates of lifetime alcohol dependence among minority race-ethnicity groups is that members of these groups are more likely to be involved in activities that shield individuals from initial exposure to alcohol.30
Heath et al
observed higher levels of religious involvement among black people, which predicted lower levels of alcohol use.31
Similarly, Chen et al
observed that adolescents with higher levels of religious participation reported less exposure to alcohol and higher levels of lifetime abstinence.30
Our findings suggest there are protective factors associated with race-ethnic minority status that reduce the risk of dependence after
initiation of alcohol use. These factors may or may not differ from those that reduce the likelihood of first alcohol use or of levels of use.
The association between education and alcohol dependence was statistically significant, but of varying magnitude, among white people, American Indians, black people and US-born Asians. The relation between education and alcohol dependence was not significant among Hispanics. Variability in the relation between SES and alcohol dependence across race-ethnic groups suggests that factors that vary by race-ethnicity modify the effect of social adversity on risk for alcohol dependence.11
Previous evidence for variation in the relation between SES and pathological alcohol use across race-ethnic groups is mixed. For example, some studies have shown inverse SES gradients in alcohol abuse or dependence that do not vary across race-ethnic groups,32 33
while others have shown that SES differences in alcohol consumption and problem drinking are stronger among black people compared to white people.34-36
Analogously to our study, Jones-Webb et al
reported that SES, as indicated by neighbourhood poverty, was more strongly related to alcohol problems among black people than among white people, and had no relation to alcohol problems among Hispanics.37
The mixed evidence from previous studies is due partly to different outcomes used, which range from levels of alcohol consumption, problem drinking and alcohol abuse, to alcohol dependence. Our analyses focused on the development of dependence following first alcohol use by excluding lifetime abstainers from the analysis sample and by restricting the person-years at risk for dependence to those beginning with age at first drink.
The pathways leading to alcohol dependence among users need to be further disaggregated in order to clarify the reasons for SES and race-ethnicity differences in lifetime dependence rates. Before first use, group differences in social norms regarding drinking have been shown to predict lifetime abstinence rates 35 38
; the same norms influencing abstinence rates have also been hypothesised to influence levels of alcohol consumption.39
For example, group differences in drinking contexts40
may influence both the level of consumption and the frequency of heavy drinking, which contribute independently to the risk of alcohol dependence.41
In addition, while higher levels of consumption are related to increasing risk of alcohol dependence,42
converging evidence from several studies suggests that the relation between consumption and dependence also varies by race-ethnicity, with higher levels of consumption predicting steeper increases in risk for dependence among white people than among black people.38 43 44
What is already known on this subject
- Risk of alcohol dependence is higher among individuals of lower socioeconomic status, but appears from several studies to be lower among some minority ethnic groups.
- The pattern of disparities in alcohol dependence contradicts that of other health conditions, in which social disadvantage and minority race-ethnicity are associated with elevated risk.
What this study adds
- The association between educational attainment, an indicator of socioeconomic status, and alcohol dependence varied across race-ethnic groups.
- Lower education was associated with a higher risk of alcohol dependence among white people, black people, Asians and American Indians, but not among Hispanics.
- Aspects of minority racial-ethnic group membership might mitigate or exacerbate the effects of socioeconomic status on alcohol dependence.
The patterns of risk for alcohol dependence—as well as other substance and psychiatric disorders29
—are unique in social epidemiology in that minority race-ethnic groups have generally lower lifetime risks when estimated from nationally representative household samples. Therefore, theoretical frameworks based on adversity-stress models are not fully adequate for understanding social group differences in the risk of alcohol dependence. These models posit higher levels of psychological exposures in the context of social disadvantage. Farmer and Ferraro described two such models: one in which the effects of poverty on health are stronger among minorities because of the uniquely toxic effects of disadvantage among minorities; the other in which minorities benefit less from educational achievements.45
Black-white differences in educational returns46 47
are the result of a combination of factors including discrimination48
and school quality.49
Previous empirical support for these types of models as applied to pathological alcohol use suggests stronger effects of SES on the level of alcohol consumption among minorities, but not necessarily on problem use or dependence.35
Our results are consistent with stronger effects of lower education on alcohol dependence among black people, Asians and American-Indians than among white people (or, in other words, reduced benefits of schooling among minorities).
Despite the large size of the NESARC and the use of measures of alcohol dependence according to diagnostic criteria, several limitations are notable. The NESARC is a cross-sectional study; therefore, our analyses relied on retrospective reports of the age at highest educational qualification and at alcohol dependence onset. Inaccuracy in these reports may have attenuated associations between education and risk for alcohol dependence. While we are unaware of evidence that the accuracy age of onset reports varies by SES or race-ethnicity, this possibility cannot be ruled out. Secondly, the current analyses did not distinguish individuals of the same ethnicity who have different backgrounds or different nativities—for example, Puerto Ricans versus Mexican Americans, nor did they identify other ethnic minority groups.11
Finally, our findings may not apply to all alcohol-exposed individuals, given that the NESARC was a household survey and therefore did not include people at high risk for alcohol dependence who were outside of the study's sampling frame, such as institutionalised individuals.
An important next step in this line of inquiry is to investigate SES differences in the course of alcohol dependence as evidenced by remission, recovery and relapse. Investigating patterns of current-year dependence also falls within the rubric of persistence insofar as alcohol dependence in the past year (among cases with onset before the year of interview) indicates the continuation of previously established disorder.3 29
The role of treatment in attenuating or exacerbating SES and race-ethnic differences is also of interest. Planned follow-up interviews of participants in the NESARC will be critical for investigating the course of disorders prospectively.