Changes over time in mental health symptoms among adolescents in Tampere, Finland

Adolescence is a time of marked growth and change (1). These changes enable young people to become adults but also put them at risk for developmental problems (1). Mental health disorders are the most common illness group in adolescence (2). Mental health disorders can be divided into internalizing and externalizing disorders (3). In internalizing disorders, the symptoms are directed at oneself, i.e. the problem is internalized (3). Examples of internalizing disorders/symptoms include depression and anxiety (3). In externalizing disorders, the symptoms are directed towards the outside world, manifesting through unwanted behavior, such as conduct problems or delinquency (3). In scientific literature, eating disorders have either been classified under internalizing disorders or considered to form their own category outside the dichotomy (4). Similarly, substance abuse can be considered to constitute a category of its own or be classified under externalizing symptoms (5).

The prevalence of mental health disorders increases as children enter early adolescence (6). As adolescents mature, externalizing symptoms become less common (7). However, a minority of adolescents exhibit a pattern of externalizing symptoms that persists into adulthood; this persistent life-course subtype of externalizing behaviors, such as delinquency, often already begins in childhood (7). Similarly, the prevalences of internalizing disorders decrease as adolescents move into adulthood although they remain high among adults as well (8). In addition, a considerable proportion of adolescents suffering from internalizing symptoms continue to suffer from these symptoms as adults (8).

Being common in adolescence, mental health problems have a huge impact on adolescents’ lives, impairing wellbeing, academic performance, and social relationships. In addition, if not addressed early enough, adolescent mental health problems may have far-reaching consequences in later life (9–11). In a US study (12), three quarters of mental health disorders in adulthood started before the age of 25. Therefore, when it comes to mental health disorders in adolescence, both prevention as well as early diagnosis and treatment are essential to prevent the harm caused by these disorders to individuals’ lives and also the effects on public health.

The world has seen drastic changes since the beginning of the 21^st century, including technological advances, the rise of social media, and an overall acceleration of the pace of life. These societal changes have raised concerns about their effects on mental health (13, 14). Concerning children and also adolescents, the accelerated pace of life and social media use may have led to increased stress and psychological suffering (13, 14).

To keep track of mental health in the population and to monitor the effectiveness of interventions on mental health disorders, data on the time trends of these disorders are needed. According to time trend studies in the 2000s and 2010s, mental health problems among Finnish adolescents have not increased (15–19). Instead, the demand for mental health services, especially for the treatment of depression and anxiety disorders, has recently increased among adolescents. The number of adolescents in psychiatric treatment has increased tremendously, likewise contacts by adolescents to primary care services due to mental health complaints (20). The rising trend in the utilization of mental health services can be seen throughout Western countries (21–23). Overall, there seems to be a huge mismatch between the stable or even decreasing trend in the prevalence of mental health problems and the increased demand for mental health services.

In Tampere University Hospital, referrals to adolescent psychiatric specialist level services increased markedly from 2015 to 2017. This prompted us to replicate an adolescent mental health survey already conducted twice, namely the Adolescent Mental Health Cohort study and its 10-year replication (24, 25). Our research questions were:

The data for this study was obtained from the Adolescent Mental Health Cohort study (AMHC). The AMHC is an anonymously completed school survey by the Tampere city administration and the Tampere University, providing time-trend data on adolescent mental health. It has been conducted among 9^th graders in Tampere, Finland, in the academic years 2002–03, 2012–13, and 2018–19. In 2002–03 the study was conducted using paper and pencil, in 2012–13 partly using paper and pencil and partly online, and in 2018–19 completely online. The number of participants was 1,483 in 2002–03, 1,293 in 2012–13, and 1,386 in 2018–19 (N = 4,162 in the whole sample). Participation in the survey was voluntary and adolescents and their guardians were informed about the voluntary nature of the study both orally and in writing. To evaluate whether increased help-seeking was due to increased concerns about common mental health symptoms, the measures of this study comprised both common mental health symptoms (drunkenness, bullying, subjective health) and more severe symptoms suggestive of mental health disorders (depression, social anxiety, eating disorders, etc.).The study was approved by Pirkanmaa Ethics Committee and the City of Tampere.

As the purpose of this study was to assess changes in self-reported mental health symptoms over time instead of the actual prevalences at a certain point in time, the cutoff points of all measures were held constant across the study waves. Therefore, the cutoff points used in the analyses between the two earlier waves were preserved in these analyses.

Statistical analyses were conducted using SPSS software. The prevalences of internalizing and externalizing symptoms among both sexes in different time periods were calculated using crosstabs with the Chi-square test. In order to avoid bias related to multiple testing, we set the limit for statistical significance at p < 0.001. The associations between internalizing and externalizing problems and time were calculated separately for both sexes using binomial logistic regression. Results are shown as odds ratios (OR) and 95% confidence intervals (CI). Age, parental education, parental employment status, and family structure were controlled for in the analyses. The distributions of these sociodemographic variables are presented in Table 1.

Compared to the period 2002–03, the prevalences of internalizing problems did not change markedly in the period 2012–13. Instead, in the period 2018–19, the prevalences of depression, social anxiety, general anxiety, poor subjective health, and poor self-esteem increased in both sexes compared to the period 2012–13. In addition, the prevalence of stress symptoms increased among boys between the period 2012–13 and 2018–19. No change or a slight decrease in prevalence was observed in bulimia, anorexia, and stress symptoms among girls (Table 2).

The prevalence of externalizing problem behaviors decreased throughout the study period. Compared to the period 2002–03, all externalizing problem behaviors showed either a decrease or no marked change in the period 2012–13, apart from frequent drunkenness among girls, which increased compared to baseline. The prevalence of lifetime drunkenness, frequent drunkenness, delinquency, and playing truant decreased from the period 2012–13 to 2018– 19 (Table 3).

The regression analyses controlling for sociodemographic confounding confirmed that among girls, depression, social anxiety, poor subjective health, and poor self-esteem increased from 2002–03 to 2018–19. General anxiety already increased statistically significantly from 2002–03 to 2012–13, and further to 2018-19, and self-reported anorexia increased between the years 2002–03 and 2012–13 among girls and between 2012–13 and 2018–19 among boys. Statistically significant increases were seen between 2012–13 and 2018–19 in social anxiety, depression, and stress symptoms among boys. (Table 4.)

Regarding externalizing symptoms among girls, statistically significant decreases were seen between the period 2002–03 and 2012–13 in lifetime drunkenness, cannabis use, delinquency, and bullying others. All externalizing symptoms decreased among girls in the period 2018–19 apart from cannabis use, which remained the same. Among boys, statistically significant decreases were found in all externalizing symptoms throughout the study period. (Table 5.)

In this study, we observed that the prevalences of externalizing symptoms decreased and those of internalizing symptoms increased among Finnish adolescents between the period 2012–13 and 2018– 19. Compared to the period 2002–03, the prevalences of externalizing symptoms decreased in the years 2012–13 and further in 2018–19. The prevalences of internalizing symptoms did not change significantly in 2012–13 compared to baseline. In 2018–19, depression, social anxiety, general anxiety, poor subjective health, stress symptoms among boys, and low self-esteem increased 1.5–2-fold compared to baseline. However, severe suicidal ideation did not increase over the study period.

Today’s Western society is decidedly characterized by an acceleration in almost every area of life (14). Intensification is a fairly new term in psychology developed and used to describe the acceleration of technology, social changes, and the pace of life in modern society (14). This acceleration can also be seen in the school world (41). The modern school system is driven by an efficiency-oriented philosophy, thereby putting a lot of pressure on adolescents who are still in search of their identities (41). Leaving little room for searching and experimenting, the school world may in part contribute to the increased burnout and mental health symptoms seen among adolescents (41).

The Finnish education system has gained international renown for its equality and academic excellence (42). Being free of charge through all levels from preschool to university, it offers children and adolescents equal opportunities for education regardless of their parents’ financial status. In addition, Finnish students have performed exceptionally well in the international tests measuring academic achievement, including the PISA tests (42). However, recent studies have observed regional differences between Finnish schools in academic achievement. School inequality is already apparent in secondary schools, especially in bigger cities, where schools located closer to the city center tend to be ranked higher in comparisons than suburban schools (43). Also, budget cuts to education, leading to bigger classes and integrating students with special education needs into mainstream classrooms, may have increased the struggles of adolescents at school (44).

Since the beginning of the 21^st century, social media has become a highly pervasive element in adolescent everyday life. In social media, people tend to post selectively only positive pictures and stories about their lives – often enhanced with editing filters – which gives viewers a skewed picture of reality (45). Comparing one’s life to the unrealistic images in social media can easily lead to feelings of relative deprivation (44). Substantial consumption of social media apps, including Instagram and Facebook, has indeed been linked to increased likelihood of suffering from internalizing symptoms, especially depression and anxiety (45, 46). On the other hand, social media may also have had a positive impact on adolescent mental health. Thanks to those with influence in social media, awareness of different mental health issues has increased significantly in recent decades (47). Influential social media participants who are role models for many young people open up about their own mental health struggles and share information on psychiatric disorders with their followers, aiming at reducing the stigma surrounding mental illness. Adolescents may therefore be better informed about mental health problems, recognize these symptoms more easily in themselves, and be encouraged to open up about their problems more than earlier.

Finally, the decline in externalizing problems that emerged prior to the recent rise in internalizing problems warrants attention. The maturity gap theory of adolescent delinquency posits that adolescents experience a discrepancy between their biological maturation, resulting in their desiring autonomy and independence, and their social maturation, i.e. the degree of autonomy allowed to them, that lags behind their biological maturation in contemporary Western societies (48, 49). Being accorded a status of restricted autonomy, adolescents start to engage in delinquent acts in an attempt to bridge the gap between their self-perceived maturity and the way society perceives them, adolescents have been shown to engage in less delinquency or desist from it when they assume adult roles and start to perceive themselves as adults. It may be that the intensifying pace of life and intensifying demands in the school world may be opportunities for unrestricted social interaction, and the opportunity to experiment with roles in social media offers contemporary adolescents a perception of themselves as responsible actors facing adult challenges, and this decreases their desire to engage in externalizing behaviors. On the other hand, the same demands may risk overwhelming the adolescents’ capacities and expose them to internalizing symptoms (48, 49).

The results of this study should be viewed with certain limitations in mind. First, the sample of this study consists of 9^th graders in one city, and therefore the results may not be generalizable to the whole of Finland. Second, as with all surveys relying on self-report data, this study is subject to bias. Most notably recall bias has to be taken into account in self-report questionnaires. Another source of error is mischievous responding: some adolescents may find it funny to exaggerate their symptoms in questionnaires. However, there is no reason to assume that such responding had increased over the years and therefore explains the increased trend in internalizing symptoms observed in this study.

Despite the limitations, this study has several strengths. It was based on a large, population-based sample that included nearly all 9^th graders in the city of Tampere. The same survey was conducted at three time points, which enabled us to study time trends in mental health symptoms. The measures of mental health symptoms were held constant across questionnaires, thereby ensuring the comparability of the results between periods.

Internalizing symptoms have increased among adolescents in the city of Tampere since the beginning of the 21^st century. At the same time, the prevalence of externalizing symptoms has decreased. Societal changes, including the accelerated the pace of life, competition in the school world, and social media may have contributed to the increase in internalizing symptoms among adolescents. To help to understand the causes of the increase and to prevent internalizing problems, further research on the underlying causes of the increased prevalence of internalizing symptoms is needed.