Alcohol misuse is common among adolescents. In a recent survey, the rate of binge drinking was about 2.4% of high school students in Japan (1). This result is lower than the data form other countries, such as 13.5% of all high school students in the 2017 Youth Risk Behavior Surveillance in the United Sates (2), 14.4% with 12th graders in the 2019 Monitoring the Future Survey in the United States (3), and 35.0% of adolescents age 16 years in the 2015 European School Survey Project on Alcohol and Other Drugs (4). However, just because the rate of binge drinking in Japan is low, we should not make light of the problems because youth binge drinking is known to increase the risk of alcohol-related disorders, such as alcohol intoxication, as well as increasing the risk of accidents, fatal injuries, and chronic illness (5). Thus, binge drinking in adolescents can be considered more hazardous than adult drinking.
Emerging health research suggests that alcohol use is determined by multidimensional factors, including biological, genetic, psychological, and sociocultural characteristics (6, 7). Genetic variants affect the risk of alcohol misuse. Candidate genes related to alcohol dependence can be categorized into three groups, those related to alcohol metabolism, the stress response system, and behavioral disinhibition (8, 9). With respect to alcohol metabolism, alcohol dehydrogenase and aldehyde dehydrogenase are known to have a protective influence against excessive drinking and alcohol dependence (10). Regarding the stress response system, the initiation and retention of binge-drinking behavior and alcohol dependence are related through dysregulated activation of the brain stress system by corticotropin-releasing hormone (11, 12). Behavioral disinhibition, defined as the inability to inhibit socially restricted actions including alcohol and other substance abuse, is related to the serotonin and dopamine pathways (13, 14). Previous studies have suggested that polymorphisms on tryptophan hydroxylase, serotonin transporter, and serotonin receptor genes in the serotonergic system and polymorphisms on dopamine receptors, dopamine β-hydroxylase, and tyrosine hydroxylase have been associated with risks for binge drinking and alcohol dependence (9, 15–17)
Psychological traits related to cognitive and emotional susceptibility to substance abuse are also crucial factors for the initiation and development of adolescent substance abuse (18). Among various psychological traits, impulsivity and sensation seeking have received the most attention owing to their influence on risky behaviors, including drinking alcohol (19, 20). High levels of sensation seeking and impulsivity are related to risk-taking behavior (21). Adolescents may be more sensitive to alcohol’s reward and stimulant effects (22) and less sensitive to its sedative effects (23). Several studies imply that neural changes occurring during adolescence may temporarily increase sensitivity to certain effects of alcohol (e.g., reward effects) that promote consumption within a drinking episode while reducing sensitivity to other effects (e.g., sedative effects) that may help to limit drinking during an episode (24).
When it comes to environmental factors, etiological mechanisms representing multiple systems (e.g., family, peers, and community) interact across development to influence binge drinking trajectories (25). Notably, the influence of parents on drinking in their children is important. Parental alcoholism and disrupted family relationships (e.g., parental separation or divorce) are both associated with binge drinking (26). Low parental monitoring, low levels of parental warmth, parental alcohol use, and parental expectations regarding their child’s alcohol use are associated with higher incidence of adolescent binge drinking (27). Binge drinking occurs in locations where there is no parental supervision, such as someone’s else’s home (28). During the high school period, the social context shifts from family to peers as important sources of influence on youth attitudes and behavior (29). Risk-taking behaviors may be facilitated by the presence of peers (30), and adolescent binge drinking tends to occur in social contexts that include peers (31). Community factors include the neighborhood and school environment. A recent study found that a supportive school environment (e.g., alcohol prevention incorporated into the curriculum) was associated with reduced adolescent binge drinking independent of individual, family, and peer risk factors (32).
The influence of alcohol on others has attracted attention in recent studies, including the potential impact of parental drinking on children. A meta-analysis of longitudinal studies highlighted parental drinking as a risk factor, together with parental provision of alcohol and parental attitudes toward drinking (33). The more the parents of adolescents drink, the more those adolescents tend to start drinking at younger ages (34, 35) and to drink larger amounts throughout adolescence (36). Parental alcohol use is predictive of both an earlier age of initiation and a greater increase in alcohol use across adolescent (37). The more often that fathers or mothers drink, the higher the scores on the Children’s of Alcoholics Screening Test (38). Several protective factors against adolescent alcohol misuse have been revealed. Four protective factors (e.g., parental monitoring, parent–child relationship quality, parental support, and parental involvement) have been identified as longitudinal predictors of both alcohol initiation and levels of later alcohol use/misuse (33). In domestic research, parental attitudes (e.g., parents who do not involve their child in the adults’ drinking, warning their child about the dangers of alcohol use, communication about alcohol use, and awareness of the actual behaviors of their child) are important risk factors (39).
A number of studies have examined the effects of prenatal drinking exposure on child alcohol misuse. However, most studies focused on alcoholics and parents who have problems with alcohol (40–42), and less research is focused on how parental drinking, including normative drinking, influences alcohol misuse among children in the general population. A systematic review found that non-dependent parental drinking was associated with harm to children, including increasing the risk of alcohol initiation or drinking escalation (43), increasing the risk of adolescent alcohol misuse (33), and alcohol-related hospitalization later in life (44).
Another challenge for research in this area has to do with inconsistent findings regarding whether parents have the greatest impact on their child, owing to small sample sizes (45). In particular, how parental drinking affects child binge drinking, according to sex, is not well known. To the authors’ knowledge, research in Japan using nationally representative data examining parental and adolescent drinking does not exist. Amongst prior studies examining the role of drinking in both the father and mother, some show that only maternal drinking is significantly associated with adolescent drinking, after controlling for paternal drinking. In contrast, a 10-year cohort study conducted in Japan revealed that exposure to frequent drinking by the father during junior high school increases the risk of problematic drinking in later life (46). Other reports have found that drinking by both parents most affects adolescent alcohol misuse(36, 47).
The impact on adolescent drinking of parental drinking according to parental structure is also ambiguous. Most studies have not investigated parental drinking, according to sex (48). Several studies show that adolescents in one-parent households are more likely to drink than those in two-parent households (34, 47). However, we could not find any studies examining how not living with either parent influences adolescent alcohol misuse. In the real world, many adolescents do not live with either parent owing to divorce or the death of a parent(49).
Therefore, in this study, we aimed to investigate the relationship between current parental drinking according to parental structure (e.g., both parents, single parent, neither parent at home) and binge drinking among high school students in Japan.