Whereas the most severe psychiatric disorders, such as psychoses, have not increased in the population in Sweden during the last decades, there has been an increase in the prevalence of nervousness and anxiety since the beginning of the 1990s [1]. One possible explanation that has been mentioned is that it has become more socially accepted to tell about nervousness or anxiety. The increased premature mortality and psychiatric morbidity associated with these symptoms has, however, been relatively stable during the last ten years, indicating that self-reported severe mental health symptoms are good indicators of psychiatric morbidity [18].
Our results show that women report mental health symptoms to a larger extent than men do. It is plausible that this has to do with the position of women in society. Even though there is a relatively high equality of opportunities between genders in Sweden, women still have a high workload both at work and at home [19] and therefore also a higher level of stress hormones [20].
Young adults have a higher prevalence of mental health symptoms than older subjects do. Nearly half of women and one third of men aged 18–34 years reported that they were moderately or extremely anxious or depressed. The prevalence of mental health symptoms decreased with age until the age of 70–74 years and increased again among those over 75 years. Many factors that have been shown to be associated with mental health symptoms in the present and other studies (such as unemployment, economic hardship and being belittled) are more prevalent among younger than older subjects.
Factors associated with mental health symptoms
Social relations are in many ways important for mental health [4]. Social support is a protecting factor that acts a buffer in psychosocial crisis situations and strain [21]. Poor social support and being belittled were strongly related with mental health symptoms in the present study. Previous studies indicate that experiences of shame are associated with poor mental health for example among the unemployed [22].
Personal economy had also a strong association with mental health symptoms. Subjects with economic problems had a higher prevalence of anxiety/depression than subjects without economic problems. Previous studies have indicated that economic hardship both at present [5, 23, 24] and under childhood [24] is strongly associated with poor mental health.
There was no association between the number of hours spent in domestic work such as taking care of children, nursing relatives, buying the groceries, cooking, washing the laundry, cleaning etc. and mental health symptoms. Instead a strong independent association was found between how burdensome domestic work was experienced and anxiety/depression. Subjects who often or all the time experienced domestic work as burdensome had an increased prevalence of mental health symptoms. This was true as well for women as for men. Previous studies have reported domestic work as a risk factor for poor health among women, particularly in combination with work-related stress [14, 20, 25], whereas the association has been less often studied or found weaker among men.
Critical life events, such as death of a near relative, own or a relative's severe illness, separation from a spouse or a partner or being laid off from work, were associated with mental health symptoms in the present study. These events can be a triggering factor for poor mental health because they require a high level of psychological adaptation [21]. There is also an association between physical ill health and mental ill health [1, 3]. In the present study, a factor that was strongly related to mental health symptoms was functional disability i.e. being dependent on help from others to manage everyday life.
Single parents have been found to have higher level of mental health problems than population in general [1, 26]. In the present study, there was a strong crude association between being single parent and mental health symptoms. This association, however, almost disappeared when adjusted for other socio-economic conditions and lifestyle factors, suggesting that the increased level of anxiety/depression among single parents can be explained by these factors. For example, burdensome domestic work and economic hardship are more prevalent among single parents than parents living together. This should be taken into consideration when reporting differences in mental health symptoms between different family constellations. On the contrary, the association between living alone and anxiety/depression remained about the same even after the adjustment.
There was also an association between country of origin and mental health symptoms. Subjects born in other European countries and outside Europe were more often anxious or depressed than those born in Nordic countries which is in line with previous studies [1]. Women had a somewhat higher prevalence of anxiety/depression than men even when socio-economic conditions and lifestyle factors were taken into account.
Working conditions, such as high demands in combination with low control at work and job insecurity have been shown to be detrimental for health [6, 7, 27]. To elucidate the role of working conditions was, however, beyond the scope of the present study. Subjects who were not employed, such as disability pensioners and the unemployed, had a higher level of anxiety/depression than the employed, which is in agreement with previous studies [1, 7, 28].
Physical inactivity was associated with mental health symptoms in the present study. This is in line with previous studies where physical activity has been shown to have a positive effect on mental health [9, 10]. Underweight subjects had a higher prevalence of mental health symptoms than normal weight subjects, especially among women, corroborating previous studies [29]. Underweight can be an effect of an eating disorder, which in turn is related to poor mental health. Contrary to previous research [13] there was, however, no association between obesity and anxiety/depression when adjusted for socio-economic and other lifestyle factors.
A high and long lasting consumption of alcohol increases the risk of alcohol related injuries, suicide, depression and anxiety [11, 12]. It has been shown in national studies in Sweden that risk consumption of alcohol is related with depression and anxiety [11]. In the present study, there was a strong independent association between risk consumption of alcohol and self-reported anxiety/depression among men.
Strengths and limitations of the study
Since the present study is based on cross-sectional data, it is not possible to say which are causes and which are effects of mental health symptoms. In many cases the relationships are bi-directional [3, 30]. For example, problems in social relations can lead to mental health symptoms, but poor mental health can also lead to problems in social relations. Economic hardship can cause anxiety or depression, but anxiety/depression can lead to economic hardship through lower income due to sickness absence or disability pension. Furthermore, burdensome domestic work can lead to mental health symptoms, but poor mental health can also lead to that one experiences domestic work as burdensome.
The response rate of the present study was 64 percent. The response rate was lower among younger than older subjects and among men compared with women. The level of education was also somewhat higher among the respondents than among the general population of the same age. Those who suffer from severe psychiatric disorders are probably underrepresented. Therefore the absolute levels of self-reported mental health symptoms should be interpreted with caution. It is, however, unlikely that the associations between mental health symptoms and other factors reported in the present study could have been explained by non-response.
A strength of the present study is that it is large and population-based. It comprises a study population of over 42,000 individuals and represents about one million inhabitants aged 18–84 years in Sweden. We could even study factors that are rare in the general population and take into account a wide range of socio-economic and lifestyle factors at the same time.
EQ-5D is an internationally validated scale of quality of life where the fifth dimension measures anxiety/depression [15, 31]. Another widely used measure of mental health is GHQ-12, the twelve-item version of the General Health Questionnaire [32], which was also measured in the present study. We used EQ-5D to analyse the association between the studied socio-economic and lifestyle factors and mental health because it gives more information about the severity of mental health symptoms than using one cut-off point for GHQ-12. The results were, however, similar when using GHQ-12 instead of EQ-5D as the dependent variable, which gives further support to the findings of the study.
As a starting point of the study, we used a model of mental health indicators which has been established in a working group in the European Union [3]. It includes e.g. social relations, economic factors, working conditions and critical life events. We were, however, able to extend the model by elucidating the importance of domestic work and lifestyle factors in the same context.