Alcohol use during early adulthood presents a serious public health problem in many countries [1, 2]. Studies have shown that heavy drinking and related problems are prevalent among young people, regardless of whether they attend college or not . The majority of studies have found higher rates of alcohol-related problems in students compared to non-students [4–6]. In contrast, a recent study showed that college students drink less frequently than their non-college peers, but when students do drink, they tend to drink in greater quantities than non-students . Among university students, first year freshmen display particularly high levels of alcohol consumption . On the one hand, first year at university is a developmental transition to new responsibilities in absence of well-established networks of social support. On the other hand, it also represents freedom, liberty and fewer restrictions due to living away from parents . Both aspects can increase the use of alcohol among students.
Generally, alcohol consumption has been linked to mental health problems e.g. perceived stress or depressive symptoms [10–15]. Depressive symptoms (based on DSM-IV) include sadness, anxiety or empty feelings; decreased energy; loss of interest in usual activities; sleep disturbances; weight gain/loss; feelings of worthlessness; suicidal thoughts; difficulty in concentrating or making decisions. Tension reduction theory contends that tension-producing circumstances (i.e. stressors) could lead to increased drinking [16–18]. As alcohol is perceived to reduce tension high levels of stress are therefore associated with drinking [19, 20], and depressive symptoms might also result in increased alcohol consumption . Indeed, college students consume alcohol to: potentially relax or relieve tension; celebrate; feel comfortable with the opposite gender; as a reward for working hard; and to get away from troubles .
Religiosity is involved in the coping processes against stress and depressive symptoms [23, 24]. Religious coping entails dealing with stress, which involves a religious perspective. Such religious coping includes prayer, congregational support, pastoral care, and religious faith . An alternative value system, which could be part of religious coping, may also improve the coping mechanism with respect to alcohol drinking behavior. The ‘net’ effects of the academic, social or economic stressors on student wellbeing might well depend on the extent of availability of coping resources in order to ‘buffer and balance’ the stress. Certainly, studies have demonstrated an inverse relationship between religiosity and alcohol use. For instance, students who reported that “religion is important in my life” had a lower frequency of heavy drinking in Nova Scotia, Canada  and in the USA [27, 28]. Similarly, American students who used religious coping tended to drink less alcohol . Such evidence suggested that religiosity could be a potential confounder or even factor that modifies the association between mental health problems and alcohol consumption.
University students in various Eastern and Western European countries differ in terms of the reported levels of perceived stress and depressive symptoms , alcohol consumption frequency, and the proportions of students with problematic alcohol use [1, 31]. Based on past history, there are still differences between countries of Eastern and Western Europe in terms of social life, health knowledge/literacy, individual habits, sense of power/powerlessness over health, and health-related lifestyles . Such lifestyle factors have been suggested to contribute to differences in health and well-being across Western and Eastern Europe . Further, given the different religious traditions with majority status in each country, personal religiosity has a potentially different association with alcohol consumption across the countries.
Although the problem of alcohol use among university students is evident almost globally [34–38], comparative studies using the same alcohol measures, identical mental health indicators and similar methodologies remain limited across countries. The current study bridges this gap by employing the same measures and identical indicators of alcohol consumption, depressive symptoms, perceived stress, and religiosity across five Eastern and Western European countries. For three of the five countries (Germany, Bulgaria and Poland), descriptive results of alcohol consumption  and of depressive symptoms and perceived stress  have been published recently. However, the associations between alcohol consumption and depressive symptoms and perceived stress were not assessed.
Aim of the study
The aim of the current study was to assess the associations of perceived stress and depressive symptoms with frequency of alcohol use and problem drinking among university students from five European countries, as well as to examine the role of religiosity for these associations. The specific objectives of the study were to:
· Assess whether perceived stress is associated with a high alcohol use frequency and problem drinking and whether this association differs by country and/or by sex. It was hypothesized that a higher level of perceived stress would be associated with more frequent alcohol use and problem drinking.
· Assess whether depressive symptoms are associated with high alcohol use frequency and problem drinking. It was hypothesized that a higher level of depressive symptoms will be associated with more frequent alcohol use and problem drinking.
· For both the above objectives, the role of religiosity was examined. It was hypothesized that religiosity modifies the associations between perceived stress or depressive symptoms on the one hand, and the frequency of alcohol use and problem drinking on the other.