The harmful use of alcohol is a major risk factor for disease, disability, and death worldwide. Globally, in 2016, 5.3% of deaths and 5.1% of disability-adjusted life years were estimated to be attributable to alcohol use [1].

Both individual and social factors, including sex, age, socioeconomic status, economic wealth, culture, alcohol availability, and social capital, influence alcohol consumption [2,3]. Evidence of associations between social capital and health behaviors has accumulated [4]. Among aspects of social capital, social participation and trust—which are known to influence each other—are considered the most important [5].

Studies have shown that individual-level indicators of social capital such as social participation or trust are negatively associated with the use of alcohol among adolescents [6-10], while a longitudinal study found that higher social capital was associated with increased binge drinking by students [11]. In research on the associations between individual-level social capital and alcohol consumption in adults, the directions of the observed relationships have been inconsistent and inconclusive and depend on the dimension of social capital analyzed, the type of alcohol measure, the country researched [12], and potentially the form of data collection used (that is, with or without an interviewer). While some studies have found negative associations [13,14] between overall social capital and heavy alcohol use, another found no clear association [15]. Similarly, depending on the study, associations between social participation and high alcohol consumption have been found to be negative [16], non-existent [17,18], or positive [12,19-22]. A study of college students showed that formal social participation was negatively associated with heavy drinking, while informal social participation was positively associated with higher alcohol use [23]. Associations between social trust and heavy alcohol use were found in several studies to be negative [18,24,25] and in one to be positive [22].

Most studies in this field have used dichotomous variables, with the presence of hazardous drinking, binge drinking, harmful alcohol consumption, problem drinking, or episodic heavy drinking as dependent variables. However, this approach fails to reflect U-shaped or J-shaped associations between alcohol consumption and all-cause mortality [26]. In a meta-analysis, mortality risk was found to be higher in abstainers than in light-to-moderate drinkers and highest in heavy drinkers [27]. Heavy drinking refers to alcohol use that exceeds a defined threshold of frequency or quantity. In reflection of the broad continuum of adverse health effects associated with the quantity or pattern of alcohol use, alcohol use disorders (AUDs) are heterogeneous and include heavy drinking, hazardous drinking, harmful drinking, and alcohol abuse and dependence [26].

The World Health Organization (WHO) developed a 10-item questionnaire, the Alcohol Use Disorders Identification Test (AUDIT), to screen for AUDs in primary health care settings [28]. The WHO guidelines indicate that AUDIT scores of 0-7 represent abstinence or relatively low-risk drinking; scores of 8-15 represent hazardous alcohol use, and scores of 16 and above indicate the harmful use of alcohol, including alcohol dependence [29].

In this study, we investigated potential associations between individual-level indicators of social capital (social participation and generalized trust) and alcohol use. We measured alcohol use via AUDIT scores because of the implications of this scoring system for health policies designed to reduce the burden associated with alcohol use.

Of the 8800 participants, 47.7% were abstainers. The overall prevalence of current alcohol use was 52.3%. The distribution of AUDIT scores was 35.8% for 0-7, 11.6% for 8-15, and 4.9% for ≥16. All socio-demographic characteristics (sex, age, marital status, educational level, occupation, level of food security, and type of administrative unit of residence), as well as self-rated health, perceived stress, and the presence of hypertension or diabetes, were found to be significantly associated with AUDIT scores (Table 1).

Both generalized trust and social participation in organizations were found to be significantly associated with AUDIT scores in simple analyses. The highest proportion of abstainers was found among respondents who indicated a high level of generalized trust. Similarly, abstainers predominated among those involved in no organizations, only in religious organizations, or only in volunteer organizations. A smaller proportion of those involved in no organizations or only in religious organizations had an AUDIT score ≥8 than among those involved in only informal, only volunteer, or formal organizations (Table 2).

The crude ORs for abstainer status (relative to AUDIT scores of 0-7) for the 3 questions of generalized trust, compared to the group of participants who gave no positive responses, were 1.11 (95% CI, 0.97 to 1.27) for 1 positive response, 1.17 (95% CI, 1.01 to 1.36) for 2, and 1.56 (95% CI, 1.37 to 1.78) for 3. The crude ORs for AUDIT scores of 8-15 based on these 3 questions in comparison to the no-positive-response group were 0.87 (95% CI, 0.71 to 1.05) for 1 positive response, 0.94 (95% CI, 0.75 to 1.16) for 2, and 0.76 (95% CI, 0.62 to 0.92) for 3. The corresponding crude ORs for AUDIT scores ≥16 were 1.01 (95% CI, 0.76 to 1.33) for 1 positive response, 0.98 (95% CI, 0.72 to 1.35) for 2, and 0.82 (95% CI, 0.62 to 1.10) for 3 (Table 3).

The crude ORs for abstainers (relative to AUDIT scores of 0-7), compared to the group of participants who reported no participation in organizations, were 0.51 (95% CI, 0.45 to 0.57) for participation in only informal organizations, 2.00 (95% CI, 1.47 to 2.71) for only religious organizations, 1.68 (95% CI, 0.79 to 3.57) for only volunteer organizations, and 0.61 (95% CI, 0.54 to 0.69) for formal organizations. The crude ORs for AUDIT scores of 8-15, similarly compared to the no-participation group, were 1.17 (95% CI, 0.97 to 1.41) for participation in only informal organizations, 0.89 (95% CI, 0.49 to 1.63) for only religious organizations, 2.02 (95% CI, 0.67 to 6.08) for only volunteer organizations, and 1.32 (95% CI, 1.09 to 1.60) for formal organizations. The corresponding crude ORs for AUDIT scores ≥16 were 0.94 (95% CI, 0.72 to 1.23) for participation in only informal organizations, 0.29 (95% CI, 0.07 to 1.19) for only religious organizations, 4.52 (95% CI, 1.49 to 13.77) for only volunteer organizations, and 1.42 (95% CI, 1.10 to 1.85) for formal organizations (Table 3).

The aORs for abstainer status (relative to AUDIT scores of 0-7) for the 3 questions of generalized trust, compared to the group of participants who gave no positive responses, were 1.15 (95% CI, 0.99 to 1.34) for 1 positive response, 1.16 (95% CI, 0.98 to 1.37) for 2, and 1.39 (95% CI, 1.20 to 1.61) for 3. The aORs for AUDIT scores of 8-15 based on these 3 questions and compared to the no-positive-response group were 0.92 (95% CI, 0.75 to 1.13) for 1 positive response, 1.04 (95% CI, 0.83 to 1.32) for 2, and 0.89 (95% CI, 0.72 to 1.11) for 3. The corresponding aORs for AUDIT scores ≥16 were 1.19 (95% CI, 0.88 to 1.60) for 1 positive response, 1.20 (95% CI, 0.85 to 1.68) for 2, and 1.20 (95% CI, 0.87 to 1.65) for 3 (Table 4).

The aORs for abstainer status (relative to AUDIT scores of 0-7), compared to the group of participants who reported no participation in organizations, were 0.61 (95% CI, 0.54 to 0.69) for participation in only informal organizations, 2.16 (95% CI, 1.57 to 2.99) for only religious organizations, 2.41 (95% CI, 1.10 to 5.29) for only volunteer organizations, and 0.65 (95% CI, 0.57 to 0.74) for formal organizations. The aORs for AUDIT scores of 8-15, similarly compared to the no-participation group, were 1.04 (95% CI, 0.85 to 1.27) for participation in only informal or ganizations, 0.97 (95% CI, 0.52 to 1.81) for only religious organizations, 1.97 (95% CI, 0.63 to 6.15) for only volunteer organizations, and 1.29 (95% CI, 1.04 to 1.60) for formal organizations. The aORs for AUDIT scores ≥16 based on similar parameters were 0.95 (95% CI, 0.71 to 1.28) for participation in only informal organizations, 0.32 (95% CI, 0.08 to 1.37) for only religious organizations, 5.67 (95% CI, 1.73 to 18.61) for only volunteer organizations, and 1.65 (95% CI, 1.22 to 2.23) for formal organizations (Table 4).

This study showed that, in communities with high mortality rates in Korea, indicators of social capital were significantly as sociated with the level of alcohol consumption regardless of the potential confounders of socio-demographic characteristics and health indices. Participants with the highest level of generalized trust or with social participation only in religious or volunteer organizations were more likely to be abstainers than participants with lower levels of generalized trust or those with participation in no organizations, informal organizations only, or formal organizations. Participants in formal social organizations (political parties, school associations, women’s clubs, environmental groups, groups for youth or older people, unions, or neighborhood watch groups), regardless of participation in informal organizations (social gatherings or adult education, sports, or other groups), were more likely to have AUDIT scores of 8-15 or ≥16 than those who did not participate in organizations. Therefore, in this study, the effects of social participation on alcohol use seemed to differ depending on the organizations in which people took part: religious, volunteer, informal, or others, including formal organizations.

Herein, we provide evidence that individual-level social capital is associated with alcohol use as measured with AUDIT scores that represented a U-shaped risk of alcohol consumption. Most studies of this subject area have used binary dependent variables and have examined only the presence of heavy or hazardous alcohol use. As a measure of alcohol use, we used the Korean version of the AUDIT questionnaire, which has high reliability, validity, and usefulness as a screening instrument for AUDs in Korea [35]. The AUDIT is currently one of the most frequently used screening tools for alcohol dependence in clinical and epidemiological research [29]. The AUDIT displays good validity for identifying AUDs in the general population, in which the prevalence of alcohol problems is lower than in clinical sample populations [36]. Our analysis also separated abstainers from the AUDIT 0-7 group because they accounted for a substantial portion (48%) of the study sample and may differ in health status and behaviors. In addition, we conducted face-to-face interviews to improve the validity of the data collection.

In this study, generalized trust seemed to be protective against alcohol use. Other studies have found similar results in adults [18,24,25] and adolescents [6,8,10]. However, this negative relationship between level of trust and alcohol use was not found in a study in the general Danish population [12]. The inverse association between individual-level interpersonal trust and heavy drinking could be explained in several ways. When facing stress, people with high trust may more easily receive social support instead of adopting unhealthy behaviors such as drinking [37]. They may be more susceptible to advice and recommendations from others, including physicians and public institutions [38]. For example, a patient with high interpersonal trust may follow a physician’s advice to stop drinking. Another possible explanation is that people with high interpersonal trust tend to be less lonely [39] and are therefore less likely to use even small amounts of alcohol when meeting others.

As Finlay et al. [23] suggested, we analyzed participation in religious organizations alone separately from participation in formal organizations because attending religious services is both a social activity and a manifestation of faith. Common religions in Korea are Protestantism and Buddhism, which have a precept of abstaining from alcohol. Similar to other studies [12,16,23], we found that participants in only religious organizations tended to exhibit relatively low alcohol consumption. However, they tended to use alcohol above recommended levels if they were also involved in any other social activities, especially formal organizations.

The results of previous studies of associations between participation in volunteer organizations and drinking are inconsistent. Though individual volunteerism has been found to be protective against heavy alcohol use in studies of college students [13,16] and younger participants [21], volunteer work was found to be associated with risky single-occasion drinking in another study that, like the present study, examined a general population [12]. In the present study, participants in only volunteer organizations were more likely to be abstainers and more likely to have AUDIT scores ≥16 than individuals who did not participate in organizations. Volunteer work may both reduce risky behavior via a set of values and facilitate social opportunities to drink, as suggested by Seid et al. [12].

Social participation in formal and/or informal organizations has been found to be associated with relatively high alcohol use and even heavy or risky alcohol consumption in prior studies [20-23]. These findings were similar to our results, with social participation in formal organizations except for religious organizations or volunteer organizations associated with low-risk drinking, hazardous drinking, and the harmful use of alcohol, including alcohol dependence. In Korea, people often dine together and consume alcohol after accomplishing an organization’s purpose, such as a group discussion or other activity. At these events, alcohol use is widely considered an important means of social interaction, and even “bottoms-up” drinking, or consuming an alcoholic beverage in a single drink, is encouraged. Participants in formal social organizations drink socially; additionally, they exist within social hierarchies determined by age or position and are sometimes influenced to drink under peer pressure. Therefore, participants in formal organizations have frequent opportunities to drink alcohol and even to consume amounts that are greater than what is recommended.

In our study, participation in informal organizations only was also associated with alcohol use, but not with heavy alcohol consumption. Although participants in informal organizations also have many opportunities to drink over meals, they seem to feel less pressure to drink. Membership in informal organizations is determined mainly by the intimacy of the relationship, unlike formal organizations, in which membership largely depends on sociodemographic characteristics. This pattern may explain why in the present study, participants in informal organizations tended to drink alcohol, but not too much.

Chuang and Chuang [19] provided evidence for the differential effects of social capital by sex. We calculated sex-specific aORs for indicators of social capital and for AUDIT score categories. Though we do not present the results in this paper, aORs were similar for both sexes, indicating a lack of differential effects. However, the aORs for generalized trust and social participation in organizations for females in the AUDIT-score 8-15 and ≥16 categories were unstable relative to the 0-7 category because of very small sample sizes, as seen in Table 1.

The present study had some limitations. First, like other studies of social capital and alcohol use, our study was based on cross-sectional survey data. An association in this type of study does not always imply a causal relationship (for example, of social capital on alcohol use). For long-term abstainers, the lack of alcohol use may precede or coincide with the development of the person’s current level of generalized trust. Otherwise, reverse causation is very unlikely. For example, it does not follow that abstaining from alcohol use in recent years would increase generalized trust or encourage a person to participate in religious or volunteer organizations. It is unlikely that the more one drinks, the more likely one is to participate in formal organizations. Nevertheless, further research using a cohort design is needed to exclude the possibility of reverse causation. Second, our survey areas were in older and rural communities with high mortality rates, which may limit the generalizability of the results. The proportion of abstainers, 48% (38% lifetime abstainers, 10% former drinkers), in this study was much higher than the 36% (7% lifetime abstainers, 29% former drinkers) previously found in a representative sample in Korea [40]. Third, we did not perform a multilevel analysis to understand the influence of contextual social capital on alcohol use because we measured social capital indicators using aggregated individuallevel questions. According to some studies [13] of alcohol consumption in adolescents or college students that have considered the effects of both individual-level and community-level social capital concurrently, community-level or college-level social capital protects against elevated or harmful alcohol use. However, the relationships between community-level or workplace-level social capital and hazardous drinking are inconsistent in the few studies that have been conducted among adults [14].

High levels of generalized trust, social participation in religious organizations only, and social participation in volunteer organizations only were each found to be protective against alcohol use. Any other social participation in formal and/or informal organizations was associated with alcohol use. Additionally, social participation in formal organizations except for religious services significantly raised the risk of hazardous or harmful alcohol drinking in communities with high mortality in Korea.