Our findings suggest that certain adverse childhood experiences increase the risk of binge drinking in adulthood even after adjustment for behavioural factors in adulthood and for the socioeconomic position in adulthood. The association was seen in both historical and the questionnaire-based data providing some cross-validation of the effects observed. Authentic historical records may give additional and more accurate information of the association although in some of the analyses there is the effect of power loss due to smaller numbers available for the analyses. According to the historical records, bingeing with any beverage showed the strongest associations with adverse childhood experiences after adjusting for age, examination year, socioeconomic position in adulthood, and behavioural factors. After adjusting for socioeconomic position in childhood or all covariates, the effect estimates did not change much, but the results no longer reached traditional levels of statistical significance.
Using questionnaire-based recall information the effect of parents' alcohol problems, death, divorce, poor parenting style, quarrelsome home, and unhappy childhood were examined separately. Parents' alcohol problems, a punishing parenting style, quarrelsome home, and unhappy childhood were associated with higher odds of binge-drinking behaviour. There is some evidence that adverse childhood experiences are interrelated [19
]. For example, parental substance use may increase the risk of inconsistent parenting, like harsh parental discipline and lack of warmth and nurturance. This result corresponds to previous research suggesting that punishing parenting style increases the risk of early alcohol drinking in adolescence [22
]. Genetics may also explain a part of the observed association, as alcohol dependence is partly inherited [31
]. On the other hand, it has been found that foster parents' alcohol problems have an influence on the drinking behaviour of the adopted children [32
The death of a parent is regarded as one of the most stressful life events that a child can experience [33
]. In a study by Melhem et al., sudden parental death was associated with higher rates of personality and substance use disorders among the offspring [34
]. However, Muñiz-Cohen et al. did not find an increased risk of health risk behaviours among the bereaved youth after nine months of the parental death by suicide, accident or a sudden natural death [35
]. In our study parental death, or divorce did not show any effect on binge drinking with different beverages in adulthood. However, there was an increased odds of being drunk once or more often a week in men whose parents' had divorced, but the results were not statistically significant. This result gives some support to the previous studies; for example, Kendler et al. found that parental separation due to divorce and other reasons than death increased the risk of alcohol dependence [21
]. Also Huurre et al. found that parental divorce predicted an excessive alcohol use in adulthood [36
]. It is suggested that the association between parental loss and alcoholism occurs because of both the environmental effects of parental loss and the genetic transmission of alcoholism risk [21
]. Parental loss may also lead to the path of socioeconomic disparities in health. For example, in our previous study social disadvantage in childhood was associated with an increased risk of acute coronary events in adulthood [37
]. However, Yang et al. did not find an association with negative childhood experiences and binge drinking using the same KIHD data; they examined the effect of separation from the parents and parental illness but did not include parents' alcohol problems, poor parenting style, or quarrelsome home in their index. In addition, they did not have historical data in their analysis [26
]. We examined also the cumulative effect of adverse childhood experiences. The men who had had three or more childhood adversities had greater odds of binge drinking behaviour compared with men without, or with one or two adversities, suggesting a dose-response relationship between the adversities in childhood and binge drinking in adulthood.
In the retrospective study design recall bias can cause underestimation of the true impact of childhood circumstances, as people may not remember all the details of the past. For example, the inability to remember childhood events is suggested to be associated with adverse childhood experiences, such as childhood sexual abuse [38
]. According to Hardt and Rutter retrospective reports in adulthood of adverse experiences in childhood can have a high rate of false negatives but few false positive reports [39
]. In the present study, the school health nurses and doctors were sent to observe the home circumstances of the boys and they regularly followed up the health and behaviour of the children. The measure for adverse childhood experiences is quite broad, but its advantage is that the measure comes from the original observations by health professionals. Overall, the results from the historical analyses could be regarded as more objective and therefore more reliable than the results from the recalled information on childhood adversities although some of the results in the historical analyses were not precise enough to draw a reliable conclusion due to the small sample size. The findings from historical analyses might have been significant in a larger sample.
By the standards of modern epidemiologic research, the school health records are a very old source of information. The records were stored by either individual schools or municipalities. Many of the old schools have been closed since those days, and at least one municipal archive is known to have been destroyed in a fire. About 9% of the original KIHD sample were Karelian refugees, who had to leave behind their schools, and in most cases, their health records, in the course of World War II. However, there is no indication that the historical final sample (n
= 839) is in any way gravely misrepresentative of the total KIHD study population although the historical sample study participants were somewhat younger, had higher socioeconomic position, and were less likely to smoke cigarettes. A potential limitation of the study is that it included only men, so the results may not be generalizable to women or outside the Finnish population. Another limitation is that although the use of external raters may be more objective than self-report for childhood factors, it is not possible to know what instructions were given to the nurses and doctors about how to report what they observed or how diligently they carried out this task because this data was not collected as part of a research study. In addition, underreporting of alcohol consumption would result in the odds ratios being biased toward the null hypothesis. Furthermore, the selection of nondrinkers as a reference group has been questioned because this group may include exdrinkers who had to stop drinking because of health problems [40
]. In this study many of those who do not drink do so because they have been heavy drinkers before and may have quit for medical reasons, so including them in the “nondrinkers” will bias associations to the null. That is why abstainers were excluded from the analyses.
This study provides evidence that childhood adversities may predict adverse drinking habits in adulthood that can have implications for social, emotional, and physical dimensions of health. It would be useful in future research to have more information about coexisting childhood stressors within families and societies at large to understand the process of binge-drinking behaviour and its association with human health risks.