Elsevier

Drug and Alcohol Dependence

Volume 169, 1 December 2016, Pages 163-170
Drug and Alcohol Dependence

Full length article
Alcohol-related blackouts across 55 weeks of college: Effects of European-American ethnicity, female sex, and low level of response to alcohol

https://doi.org/10.1016/j.drugalcdep.2016.10.026Get rights and content

Abstract

Background

While high blood alcohol concentrations (BACs) are required for alcohol-related blackouts (ARBs), additional characteristics also contribute to the risk, including a person’s ethnicity, sex, and phenotypes relating to heavier drinking. Few prospective studies of ARBs have evaluated how these additional characteristics interact.

Method

Data regarding 398 European American (EA), Asian and Hispanic students were extracted from a 55-week prospective study of different approaches to decrease heavy drinking among college freshmen. Information on past month ARB frequency was determined at 8 assessments. While controlling for the prior month maximum BAC and active education vs. control group assignment, the patterns and intensities of ARBs over time across ethnic groups were evaluated with ANOVA at each follow-up for the full sample, and then separately by sex and then by low vs. high levels of response to alcohol status (LR). The overall pattern of ARBs over time was evaluated with a 3 ethnic groups by 2 sexes by 2 LR status by 8 time points mixed-design ANOVA.

Results

Higher rates of ARBs over time were associated with EA ethnicity, female sex and a low LR to alcohol, with the ethnic differences in ARBs most robust in females and drinkers with high LRs. Participation in education programs aimed at heavy drinking was associated with decreases in ARBs.

Conclusions

The data indicate that in addition to BACs achieved, propensities toward ARBs relate to complex interactions between additional risk factors, including ethnicity, sex, and LR status.

Introduction

Lifetime risks for alcohol-related blackouts (ARBs) in many surveys is >50% among drinkers (Barnett et al., 2014, Schuckit et al., 2015, White et al., 2002). The high blood alcohol concentrations (BACs) involved (Goodwin, 1995, Perry et al., 2006) and the compromised cognitive processes inherent in ARBs (Silveri et al., 2014) increase risks for additional serious consequences, including accidents, unwanted sex, and exposure to other forms of violence (Hingson et al., 2016, Mundt and Zakletskaia, 2012, White et al., 2004). In addition to BACs > 0.20 g/dl needed for most blackouts, ARBs are also associated with European American [EA] ancestry, female sex, and several genetically-influenced phenotypes related to heavier drinking, including a low level of response (low LR) to alcohol, as described further below (Marino and Fromme, 2015, Marino and Fromme, 2016, Schuckit et al., 2015, Schuckit et al., 2001, Wetherill and Fromme, 2016, Wetherill and Fromme, 2009, White et al., 2015). However, the relationships among these characteristics and ARBs are complex and their potential interactions have not been adequately evaluated (Wetherill and Fromme, 2016).

The link of ethnicity to ARBs may relate to heavier drinking in EAs and, potentially, Hispanics, compared to other populations such as Asian individuals (LaBrie et al., 2011, Marino and Fromme, 2015). Ethnic differences may also reflect divergent patterns of alcohol metabolizing enzymes, as Asians have higher rates of mutations in both aldehyde dehydrogenase (ALDH 2,2) and alcohol dehydrogenase (ADH1B) that produce greater alcohol sensitivities and contribute to lower levels of heavier drinking with subsequent lower rates of ARBs (Eng et al., 2007, Luczak et al., 2011). EAs, Asians, and Hispanics also differ on cultural-based proscriptions against heavy drinking, especially in women (e.g., Chartier and Caetano, 2009), have different rates of low LRs unrelated to alcohol metabolism (Ehlers et al., 2004, Luczak et al., 2002), and vary regarding typical body mass indices, with the latter likely to affect BACs per drink (Centers for Disease Control, 2015).

One contributor to higher ARB rates in women (Marino and Fromme, 2015, Schuckit et al., 2015) may be their higher BACs per drink (Baraona et al., 2001, Rose and Grant, 2010). This reflects women’s likely lower body weight, less first pass metabolism of alcohol, and higher body fat with corresponding less body water per pound. However, there is overlap between ethnic background and drinking patterns among women, and it is not clear if those two characteristics interact regarding ARBs.

Both ethnicity and sex also relate to low LRs to alcohol (Eng et al., 2005, Luczak et al., 2006, Marino and Fromme, 2016, Schuckit et al., 2016c, Wetherill and Fromme, 2009). However, LR differences across EA, Hispanic, and Asian individuals (e.g., Ehlers et al., 2004, Luczak et al., 2002), and across sexes (Schuckit et al., 2012b) raise questions about how LR interacts with ethnicity and sex to contribute to ARBs.

A recent review highlighted the paucity of prospective studies evaluating how multiple risk factors interact in contributing to ARBs, while controlling for alcohol quantities (Wetherill and Fromme, 2016). In response, the present analyses extracted information from a 55-week prospective study that evaluated educational approaches to preventing heavy drinking on campus (Schuckit et al., 2016a). The data tested four hypotheses: Hypothesis 1 states that relationships of ethnicity to ARBs will remain even after controlling for the maximum number of drinks consumed, with the highest ARB prevalence in EA and Hispanic and the lowest rates in Asian students. Hypothesis 2 is that ARB rates will be higher in females, and that the ethnic differences will remain robust after considering sex and controlling for maximum drinks. Hypothesis 3 proposes that low LRs will relate to ARBs, and that ethnic differences will remain even after considering maximum drinks and LR. Hypothesis 4 states that ethnic group status will interact with sex and LR to predict rates of ARBs over 55 weeks.

Section snippets

Original subject selection and education group assignment

Following University of California, San Diego (UCSD) Human Protections Committee approval, in January 2014, 18-year-old freshmen were selected from respondents to questionnaires emailed to UCSD students to solicit participants for a 55-week study of ways to diminish heavy drinking in college students (Schuckit et al., 2016a, Schuckit et al., 2016b). No student was selected because of current or past alcohol problems, and based on questions extracted from the Semi-Structured Assessment for the

Results

At baseline, the 398 eligible participants were 18-year-old UCSD freshmen, of whom 62% were female with 40% EA, 20% Hispanic, and 41% of Asian descent (Table 1). Table 2 presents the numbers of subjects across combinations of ethnicities, sex, and LR groups. The SRE values averaged 4 drinks across four possible effects actually experienced the first five times they drank. In the prior month, these students consumed on average 6 maximum and 4 usual drinks per occasion, with 4 drinking occasions

Discussion

Alcohol-related blackouts are highly prevalent phenomena associated with potentially severe problems (Hingson et al., 2016, Wetherill and Fromme, 2016). Recently, the prevalence of ARBs has reached alarming rates, especially in females and individuals with early onset drinking (Marino and Fromme, 2015, Schuckit et al., 2015, White et al., 2015). The UCSD freshmen studied here are no exception to these trends as 43% of these students reported at least 1 ARB during the 55 weeks, including 48% in

Role of funding

Marc A. Schuckit, M.D.: NIH/NIAAA provided funding for the research study (grant AA021162), and had no involvement in the study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.

Tom L. Smith, Ph.D.: Nothing declared.

Priscila Dib Goncalves, Ph.D.: The Brazilian National Council for Scientific and Technological Development, CNPq (203313/2014-3) funded the post-doc fellowship for Dr. Dib Goncalves

Contributors

Dr. Schuckit was the principle investigator who designed the study, supervised the collection, analysis and interpretation of data, played a major role in writing the report and deciding to submit the manuscript.

Dr. Smith was principle statistician on the research project, actively collected, and analyzed the data, and was a major participant in writing the manuscript.

Dr. Dib Goncalves participated in writing of certain sections of paper, in particular the Methods, and assisted in data analyses.

Conflicts of interest

None declared.

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