Upper secondary school diploma and mental health in emerging adulthood: examining the severity and co-occurrence of depression and anxiety symptoms

Abstract

Background:

A significant proportion of young people in Sweden do not graduate from upper secondary school with a complete diploma, which may be crucial for their mental health. A diploma influences both perceived and actual future prospects, including access to tertiary education and employment opportunities. Additionally, education fosters personal control and problem-solving skills relevant to stress management and self-esteem. Therefore, this study explores the association between obtaining an upper secondary diploma and the severity and co-occurrence of depression and anxiety symptoms among emerging adults in Sweden.

Methods:

Data from a population-based cohort of Swedish 21-year-olds (n=3255) were analysed. Depression and anxiety symptoms were measured using the Patient Health Questionnaire-4 (PHQ-4). Registry data provided information on upper secondary education, sex, immigrant background, and parental education. Multinomial logistic regression was used.

Results:

Participants without an upper secondary diploma were at a higher risk of experiencing the most severe outcomes; that is, severe symptoms (vs. normal/mild) and co-occurring depression and anxiety symptoms (vs. no symptoms) compared with those with an academic diploma. They also had a higher risk of depression only, but not anxiety only. Additionally, compared with participants with an academic diploma, those with a vocational upper secondary diploma exhibited an elevated risk of depression only.

Conclusions:

This study highlights the link between an upper secondary diploma and mental health in emerging adulthood. It also suggests that depression, anxiety, and their co-occurrence may have distinct determinants. The findings indicate that initiatives to support school completion and re-engagement could have significant public health benefits.

Keywords

Educational attainment depression anxiety mental health Patient Health Questionnaire-4 (PHQ-4)emerging adulthood Sweden

Introduction

Educational attainment is a key social determinant of health, driving both economic and social stability, which are fundamental to mental wellbeing [1]. Yet, a substantial proportion of young people in Sweden do not graduate from upper secondary school with a complete diploma, limiting their future opportunities for higher education and access to the labour market [2]. This lack of an upper secondary diploma can lead to feelings of failure, reduced self-esteem, and increased stress, which may negatively impact mental health. Education also equips individuals with essential resources for coping with stress, such as problem-solving skills, self-direction, and a sense of personal control [3]. Such skills enable individuals to manage challenges, anticipate risks, and make informed decisions, fostering psychological resilience. Accordingly, those who do not complete their education are likely to miss out on these critical resources, leaving them less equipped to navigate stress and uncertainty as they transition into adulthood.

A systematic review by Esch et al. [4] found that internalising disorders frequently emerge following school dropout. Leaving school without qualifications can hinder both professional and social integration, limiting educational and career opportunities. A Norwegian study further demonstrated that dropping out of upper secondary school is strongly associated with an increased risk of sickness and disability in young adulthood [5], highlighting the far-reaching consequences of educational disengagement. This can leave young adults more vulnerable, increasing the likelihood of developing a mental disorder such as depression or anxiety [4,6].

Mental health problems are common among young people, with depression and anxiety ranking among the most prevalent conditions. Symptoms of depression and anxiety vary in severity, with higher symptom levels linked to significant declines in mental, social, and physical functioning [7]. As depression and anxiety may have different determinants, it is also essential to analyse symptoms both individually and in relation to their co-occurrence. Furthermore, co-occurring symptoms of depression and anxiety are associated with greater functional impairment, higher distress, and worse long-term outcomes compared with either condition alone [8].

The association between upper secondary completion and depression and anxiety symptoms in emerging adulthood remains underexplored. This study aims to address this gap by investigating both the severity and co-occurrence of these symptoms, providing a deeper understanding of mental health challenges during this sensitive life stage. Using survey data from a population-based cohort of Swedish individuals born in 2001, this research examines the relationship between completing upper secondary school by age 20 years and the severity and co-occurrence of depression and anxiety symptoms at age 21 years.

Materials and methods

Data and participants

This study is based on data from Futura01, a nationally representative cohort study of individuals born in 2001. Data collection began in 2017, when participants were in the 9th grade and aged 16 years. Out of 500 randomly selected schools (one class per school), 343 schools (69%) agreed to take part in the initial survey (t1). Participating and non-participating schools did not differ significantly in terms of students’ grade point average, the proportion of highly educated parents, or the percentage of parents with a foreign background [9]. Within the participating schools, 5722 students (85%) consented to participate and completed a classroom questionnaire. After excluding individuals with missing information on key variables, the final sample comprised 5537 participants. The second wave (t2) was conducted when participants were 18 years old, with 4141 individuals responding via a web or postal survey. The third wave (t3), administered as a web survey to participants at age 21 years, saw responses from 3396 participants. Data linked from administrative registers provided additional details on parental education and country of birth. Individuals with missing information on any of the study variables were excluded from the analyses, resulting in an analytical sample consisting of 3255 individuals aged 21 years who participated in wave 3 and had complete data for all variables analysed in this study.

Measures

Depression and anxiety symptoms were assessed in the third wave of the Futura01 survey using the Patient Health Questionnaire-4 (PHQ-4), an ultra-brief screening tool developed to identify both depression and anxiety [7,10]. The opening question reads: ‘Over the last 2 weeks, how often have you been bothered by any of the following problems?’ The items are: (a) ‘Feeling nervous, anxious or on edge’; (b) ‘Not being able to stop or control worrying’; (c) ‘Little interest or pleasure in doing things’; and (d) ‘Feeling down, depressed, or hopeless’. The response options are ‘Not at all’ (0); ‘Several days’ (1); ‘More than half the days’ (2); and ‘Nearly every day’ (3). The PHQ-4 combines the subscales PHQ-2, addressing core criteria for depression (items c and d), and the Generalised Anxiety Disorder – two items (GAD-2), addressing core symptoms of anxiety (items a and b). Both PHQ-2 and GAD-2 had a total score range of 0 to 6, whereas PHQ-4 had the total score range of 0 to 12. Cronbach’s alpha was 0.81 for PHQ-4, 0.67 for PHQ-2, and 0.85 for GAD-2.

For the purposes of this study, symptom severity was categorised into three levels: normal/mild (0–5), moderate (6–8), and severe (9–12), based on established cut-off scores on the PHQ-4 [7]. Additionally, a four-category variable was constructed to capture the co-occurrence of depressive and anxiety symptoms, combining the PHQ-2 and GAD-2 scales to classify individuals into groups [7]. Here, a cut-off score of 3 was applied for both PHQ-2 and GAD-2, as recommended by Löwe et al. [11], with scores 0–2 indicating no symptoms and scores 3–6 indicating symptoms of depression and anxiety, respectively. By combining these binary indicators, four groups were created: no depression or anxiety symptoms, depression only, anxiety only, and co-occurring depression and anxiety.

A study of the adult general population in several countries including Sweden demonstrates that the PHQ-4 is a valid and reliable measure that can be applied to screen for depression and anxiety in the general population [12]. Using the recommended cut-off of 3 or more, the PHQ-2 has shown a sensitivity of 83% and a specificity of 90% for detecting major depressive disorder. Similarly, the GAD-2 with the same cut-off demonstrated a sensitivity of 86% and a specificity of 83% for identifying generalised anxiety disorder [10]. Psychometric analyses of the PHQ-4 among young adults in various settings worldwide have demonstrated adequate properties [13 –15]; however, studies based on data from young adults in Sweden remain scarce.

Register data on upper secondary diploma categorised participants into three groups based on their educational attainment at age 20 years: (1) academic upper secondary diploma; (2) vocational upper secondary diploma; and (3) no upper secondary diploma. The last group includes individuals who completed some but not all courses required for an upper secondary diploma as well as those who never started upper secondary school. This classification accounts for an additional year beyond the standard trajectory, as upper secondary education is typically completed by age 19 years, although some individuals may obtain their diploma later.

Prior research has shown that both educational attainment and mental health can vary based on sociodemographic characteristics, such as sex [16,17], immigrant background [18,19], parental education [20,21], and family structure [22,23]. Consequently, these were included as control variables.

Sex was determined using the participants’ personal identity numbers, classifying individuals as male or female.

Data on immigrant background were based on register records regarding country of birth of the participants and their parents. Three categories were created: (1) born in Sweden with at least one parent born in Sweden; (2) born in Sweden with both parents born abroad; and (3) born abroad.

Information on parental education was obtained from register records detailing the father’s and mother’s educational attainment in 2017. Highest parental education was classified into: (1) 2 years upper secondary school or less; (2) at least 3 years upper secondary school; and 3) tertiary education.

Family structure was assessed in 2017; that is, at age 16 years, when adolescents typically reside with their caregivers, using the question, ‘How do you live?’ with response options including ‘Live with mother and father’, ‘Live with mother’, ‘Live with father’, and ‘Live about half the time with mother and half the time with father (shared residence)’. Based on these responses, four categories were created: ‘two parents’, ‘single parent’, ‘shared residence’, and ‘other or missing’.

Statistical analysis

To investigate the association between educational attainment at age 20 years and mental health outcomes at age 21 years, multinomial regression analyses were performed. In the first set of analyses, depression and anxiety symptom severity was used as the outcome. In the second set of analyses, depression and anxiety symptom co-occurrence served as the outcome. The primary predictor of interest was upper secondary diploma attainment. The crude models evaluated educational attainment and other sociodemographic predictors separately, while fully adjusted models accounted for all covariates. All two-way interaction between educational attainment and the sociodemographic characteristics was tested and evaluated using Wald tests, comparing model fit between models with and without the respective interaction terms. We assessed multicollinearity using variance inflation factors (VIF). All predictors had VIF values well below the commonly used threshold of 10, indicating no problematic multicollinearity.

To account for potential pre-existing mental health issues that might influence the observed relationships, we performed sensitivity analyses incorporating psychosomatic complaints at age 18 years as a proxy for prior mental health problems. These complaints were measured using an additive index based on the frequency of headache, stomach ache, and sleeping difficulties [24]. Previous analyses using the same data have shown that these psychosomatic complaints are associated with later depression and anxiety symptoms [25]. Additionally, because attention deficit hyperactivity disorder (ADHD) has been associated with both educational attainment [26] and depression and anxiety [27], we conducted sensitivity analyses incorporating self-reported lifetime use on ADHD medication at age 18 years as a proxy to account for the potential influence of ADHD diagnosis on the observed associations.

The presented estimates are relative risk ratios (RRR) and 95% confidence intervals (CIs). Robust standard errors were estimated to take the clustered data structure into account, with students nested in classes at baseline. The number of classes was 335. All analyses were performed using Stata, version 17 [28].

Results

Descriptive statistics for the study sample are provided in Table I, including distributions of the independent, dependent and control variables in the total sample and separately for male and female participants.

Table I.

Descriptives (n=3255).

	All(n=3255)		Males(n=1420)		Females(n=1835)
	n	%	n	%	n	%
Upper secondary diploma
Academic	2098	64.4	880	62.0	1218	66.4
Vocational	556	17.1	264	18.6	292	15.9
None	601	18.5	276	19.4	325	17.7
Depression and anxiety symptom severity (PHQ-4)
No/mild (scores 0-5)	2530	77.7	1195	84.2	1335	72.7
Moderate (scores 6-8)	453	13.9	151	10.6	302	16.5
Severe (scores 9-12)	272	8.4	74	5.2	198	10.8
Depression and anxiety symptom co-occurrence (PHQ-4)
No depression or anxiety symptoms	2029	62.3	994	70.0	1035	56.4
Depression only	352	10.8	183	12.9	169	9.2
Anxiety only	393	12.1	93	6.5	300	16.4
Depression and anxiety	481	14.8	150	10.6	331	18.0
Immigrant background
Born in Sweden, at least one parent born in Sweden	2672	82.1	1177	82.9	1495	81.5
Born in Sweden, both parents born abroad	310	9.5	127	8.9	183	10.0
Born abroad	273	8.4	116	8.2	157	8.6
Parental education
Tertiary	2117	65.0	948	66.8	1169	63.7
⩾3 years upper secondary	632	19.4	273	19.2	359	19.6
⩽2 years upper secondary	506	15.6	199	14.0	307	16.7
Family structure
Two original parents	2286	70.2	1020	71.8	1266	69.0
Single parent	439	13.5	160	11.3	279	15.2
Shared residence	444	13.6	202	14.2	242	13.2
Other/missing	86	2.6	38	2.7	48	2.6

Table II presents the results from multinomial regression analyses examining depression and anxiety symptom severity. The fully adjusted analyses revealed that participants with no upper secondary diploma had significantly higher risks of moderate (RRR 1.81, 95% CI 1.39, 2.35) and severe (RRR 2.34, 95% CI 1.68, 3.27) symptoms compared with those with an academic diploma, while no statistically significant differences between the type of diploma were observed. One statistically significant interaction was detected, namely between upper secondary diploma and immigrant background (P = 0.017). Stratified analyses (not shown) indicated that there was no association between upper secondary diploma and the outcome in participants who were born abroad.

Table II.

Depression and anxiety symptom severity (PHQ-4) at age 21 by upper secondary diploma, sex, immigrant background, and parental education. Relative risk ratios with 95% confidence intervals from multinomial regressions (reference category=no/mild symptoms) (n=3255).

	Moderate (scores 6-8)		Severe (scores 9-12)
	Crude^a	Adjusted^b	Crude^a	Adjusted^b
	RRR(95% CI)	RRR(95% CI)	RRR(95% CI)	RRR(95% CI)
Upper secondary diploma
Academic	1.00	1.00	1.00	1.00
Vocational	0.86 (0.64, 1.15)	0.86 (0.64, 1.15)	1.08 (0.76, 1.55)	1.24 (0.84, 1.82)
None	1.92 (1.50, 2.45)	1.81 (1.39, 2.35)	2.31 (1.72, 3.11)	2.34 (1.68, 3.27)
Sex
Male	1.00	1.00	1.00	1.00
Female	1.79 (1.44, 2.23)	1.80 (1.44, 2.25)	2.40 (1.82, 3.14)	2.48 (1.87, 3.29)
Immigrant background
Born in Sweden, at least one parent born in Sweden	1.00	1.00	1.00	1.00
Born in Sweden, both parents born abroad	1.38 (0.99, 1.92)	1.16 (0.83, 1.62)	1.54 (1.05, 2.24)	1.48 (0.98, 2.22)
Born abroad	1.74 (1.26, 2.40)	1.45 (1.00, 2.08)	1.61 (1.05, 2.49)	1.42 (0.88, 2.29)
Parental education
Tertiary	1.00	1.00	1.00	1.00
⩾3 years upper secondary	1.07 (0.82, 1.40)	1.03 (0.78, 1.35)	0.81 (0.59, 1.13)	0.69 (0.49, 0.96)
⩽2 years upper secondary	1.53 (1.21, 1.94)	1.23 (0.96, 1.59)	1.21 (0.87, 1.69)	0.82 (0.57, 1.19)

Includes one variable at a time.

Mutually adjusts for all displayed variables and family structure. Model fit: Wald χ²(20) = 156.00, p < 0.001; Pseudo R² =0.035.

The results from Table III highlight the associations between upper secondary school attainment and the co-occurrence patterns of depression and anxiety symptoms. The adjusted model shows that compared with those with an academic upper secondary diploma, participants with a vocational diploma had an elevated risk of depression only (RRR 1.55, 95% CI 1.14-2.09). Those without an upper secondary diploma had a significantly higher risk of depression only (RRR 1.71, 95% CI 1.28, 2.29) and co-occurring depression and anxiety (RRR 2.25, 95% CI 1.74, 2.93). No statistically significant associations were observed between secondary school attainment and the risk of anxiety only. One interaction between upper secondary school attainment and the covariates was statistically significant – specifically, between upper secondary diploma and immigrant background (P=0.026). Stratified analyses (not shown) indicated that the association between upper secondary diploma and depression and anxiety symptom categories varied across immigrant background groups. In particular, individuals born abroad showed somewhat different patterns: there were no statistically significant differences in depression only or in co-occurring depression and anxiety by upper secondary diploma. Additionally, among participants born abroad, those with a vocational diploma had a significantly lower risk of reporting anxiety only, whereas no statistically significant differences in anxiety only were observed among the Sweden-born groups. However, these results should be interpreted with caution, as small cell sizes and the testing of multiple interactions increase the likelihood that this finding could reflect random variation rather than substantive effects.

Table III.

Depression and anxiety symptom co-occurrence (PHQ-4) by upper secondary diploma, sex, immigrant background, and parental education. Relative risk ratios with 95% confidence intervals from multinomial regressions (reference category=no depression or anxiety symptoms) (n=3255).

	Depression only		Anxiety only		Depression and anxiety
	Crude^a	Adjusted^b	Crude^a	Adjusted^b	Crude^a	Adjusted^b
	RRR(95% CI)	RRR(95% CI)	RRR(95% CI)	RRR(95% CI)	RRR(95% CI)	RRR(95% CI)
Upper secondary diploma
Academic	1.00	1.00	1.00	1.00	1.00	1.00
Vocational	1.58 (1.18, 2.11)	1.55 (1.14, 2.09)	0.77 (0.57, 1.04)	0.77 (0.56, 1.06)	1.01 (0.75, 1.37)	1.07 (0.78, 1.45)
None	1.85 (1.39, 2.46)	1.71 (1.28, 2.29)	0.74 (0.54, 1.03)	0.75 (0.53, 1.05)	2.41 (1.89, 3.07)	2.25 (1.74, 2.93)
Sex
Males	1.00	1.00	1.00	1.00	1.00	1.00
Females	0.89 (0.71, 1.11)	0.90 (0.72, 1.13)	3.10 (2.37, 4.05)	3.06 (2.34, 4.00)	2.12 (1.71, 2.63)	2.14 (1.71, 2.67)
Immigrant background
Born in Sweden, at least one parent born in Sweden	1.00	1.00	1.00	1.00	1.00	1.00
Born in Sweden, both parents born abroad	1.31 (0.93, 1.84)	1.25 (0.88, 1.77)	0.87 (0.59, 1.29)	0.86 (0.58, 1.29)	1.74 (1.30, 2.34)	1.52 (1.12, 2.06)
Born abroad	1.93 (1.35, 2.76)	1.83 (1.26, 2.65)	1.22 (0.81, 1.83)	1.27 (0.82, 1.96)	1.94 (1.37, 2.74)	1.61 (1.09, 2.37)
Parental education
Tertiary	1.00	1.00	1.00	1.00	1.00	1.00
⩾3 years upper secondary	1.29 (0.97, 1.72)	1.17 (0.87, 1.56)	1.22 (0.94, 1.58)	1.27 (0.97, 1.66)	0.97 (0.74, 1.27)	0.85 (0.65, 1.13)
⩽2 years upper secondary	1.34 (0.99, 1.82)	1.04 (0.75, 1.45)	1.00 (0.73, 1.39)	1.01 (0.71, 1.45)	1.61 (1.26, 2.06)	1.12 (0.86, 1.46)

Includes one variable at a time.

Mutually adjusts for all displayed variables and family structure. Model fit: Wald χ²(30) = 310.74, p < 0.001. Pseudo R² = 0.037.

Regarding the control variables, female participants were consistently more likely to report symptoms, except in the analyses of symptom co-occurrence, where no sex differences were observed for depression only. In many cases, having an immigrant background was associated with a higher risk of symptoms. Parental education, however, showed no consistent association with symptoms, particularly in the adjusted models.

Sensitivity analyses, which included psychosomatic complaints at age 18 years as a proxy for earlier mental health problems, had minimal impact on the estimates related to educational attainment for both outcomes (see Supplemental Table I). Similarly, sensitivity analyses accounting for ADHD medication use showed only minimal impact on the observed associations (Supplemental Table II).

Discussion

This study investigated the association between educational attainment and depression and anxiety symptoms among young adults in Sweden, providing complementary insights into their distinct and overlapping dimensions by focusing on both symptom severity and co-occurrence patterns. The findings reveal that not having a complete upper secondary diploma was consistently associated with elevated risks of moderate and severe symptoms of depression and anxiety. In terms of symptom patterns, not having completed upper secondary education was associated with a higher risk of both depression only and co-occurring depression and anxiety symptoms, compared with having an academic diploma. Participants with a vocational upper secondary diploma also exhibited an elevated risk of depression only compared with those with an academic diploma. However, no differences in anxiety only were observed between groups based on upper secondary education.

The results indicate that educational attainment plays a critical role in shaping mental health trajectories during young adulthood, with the absence of a secondary qualification contributing to heightened risks of psychological distress. This level of education is essential for both perceived and actual prospects, including access to tertiary studies and stable employment opportunities. Without it, individuals face limited job options and a higher likelihood of economic hardship [29], factors that are closely linked to poorer mental health [30]. Furthermore, school non-completion may contribute to social exclusion, feelings of failure, reduced self-esteem, and increased stress [3,31]. According to Ross and Mirowsky [32], educational attainment fosters a sense of control over one’s life, reducing depression by encouraging active problem-solving and mitigating feelings of helplessness. Lower levels of education, on the other hand, may lead to heightened powerlessness due to restricted opportunities, thus increasing vulnerability to emotional distress [32]. Education also enhances access to supportive social networks and prepares individuals to navigate complex social environments, weigh risks, and make informed decisions, reducing exposure to harmful circumstances and buffering against psychological distress [3]. Thus, failing to obtain a secondary school diploma can restrict these resources, leaving individuals less equipped to manage challenges. Over time, these disadvantages may compound, amplifying the risk of mental health issues [32].

This study highlights notable differences in the associations between educational attainment and different measures of mental health outcomes, suggesting that depression, anxiety, and their co-occurrence may have distinct determinants. Participants with no diploma were consistently at the highest risk for severe symptoms and co-occurrence, which are considered the most severe outcomes [7]. This pattern underscores the vulnerability of individuals who do not complete upper secondary education, particularly in terms of their long-term mental health and wellbeing. Interestingly, participants without a diploma did not show an increased risk of anxiety-only symptoms. This pattern is broadly consistent with a Norwegian study of adults, which found that educational level was more strongly associated with depression and co-occurring depression and anxiety than with anxiety alone, suggesting that anxiety may be less sensitive to educational differences [33]. Anxiety is responsive to both daily and chronic stressors, whereas depression develops primarily following prolonged or cumulative stress [34]. While day-to-day school, work, and social challenges are common among emerging adults in general [35], chronic stress is likely to be more prevalent among individuals without an upper secondary diploma due to uncertainty about future prospects, financial insecurity, and limited opportunities. This distinction may help explain why individuals without a diploma have an increased risk of depression and co-occurring symptoms, whereas no such pattern is observed for anxiety only.

The findings also revealed that vocational diploma holders were at an elevated risk of depression only compared with those with an academic diploma, but not for anxiety or co-occurring symptoms. In Sweden, vocational upper secondary programmes provide broad basic education within a vocational field while also offering a foundation for further studies [36]. According to statistics from the Swedish National Agency for Education [37], among students who graduated from a vocational programme in the school year 2019/2020, 64% had a stable position in the labour market 3 years later, while 16% had an insecure or weak position. The remaining students were either in higher education (9%), other studies (8%), or had missing information on education or labour market activity (3%). In contrast, among graduates from academic tracks, 59% were in higher education 3 years later, 22% had a stable labour market position, and 8% had an insecure or weak position; a further 9% were in other studies, and information was missing for 2% [37]. The higher probability of an insecure or weak labour market position among vocational diploma holders may be one reason for the elevated risk of depression in this group. Additionally, jobs linked to vocational pathways are more likely to involve not only job insecurity but also more limited prospects for career advancement [36]. Such structural challenges can undermine feelings of control and future prospects, fostering hopelessness and low self-worth, which are closely linked to depression. In contrast, anxiety is more often associated with hyperarousal [7], which, together with performance pressure, may be more prevalent among students in academic tracks who face high expectations for continued education and competitive career paths.

Sex differences in mental health outcomes also varied depending on the type of symptom. While women generally reported higher risks, this was not observed for depression only, where men and women had similar reporting rates. Previous analyses of the PHQ-2 instrument using the same data showed that women reported higher frequencies of the item ‘feeling down, depressed, or hopeless’ than men, whereas no statistically significant sex difference was found for the item ‘little interest or pleasure in doing things’ [25]. The role of immigrant background was less clear and warrants further investigation. In instances where parental education was associated with mental health measures, the association weakened and became non-significant when controlling for other variables. An unexpected result was that mid-level parental education (⩾3 years of upper secondary school) was associated with the lowest risk of severe depressive and anxiety symptoms. One possible explanation is that this group combines socioeconomic stability with lower academic pressure than highly educated families, while providing more resources than households with low parental education, which may help protect mental health during the transition to adulthood.

Importantly, the classification of anxiety and depression plays a critical role in interpreting findings. Using a combined variable such as ‘anxiety and/or depression’ may mask distinct patterns, as the associations for anxiety, depression, and their co-occurrence may differ and potentially cancel each other out. These findings emphasise the importance of examining these outcomes separately to avoid oversimplification and to uncover meaningful differences in determinants. It is also worth noting that the measures of symptom severity and co-occurrence overlap to some extent, as individuals classified with severe symptoms must meet the threshold for both depression and anxiety. Specifically, this classification requires a score of at least 3 on both the PHQ-2 and GAD-2 scales, given that the total range for severe symptoms is 9–12.

A key strength of this study is the use of data from a large, population-based sample of young people in Sweden. Additionally, the incorporation of sociodemographic information from high-quality register data enhances the reliability of the findings by accounting for potential confounders. Further, this study uses the PHQ-4 [7,10] to measure self-reported symptoms of depression and anxiety, enabling the identification of individuals who may experience symptoms but have not been diagnosed. This approach accounts for individuals who encounter barriers to seeking or receiving care and are therefore missing from registry data on psychiatric care. It also captures a broader spectrum of symptom severity, including milder cases that may otherwise go unnoticed. However, despite a relatively high response rate, attrition may have affected the generalisability of the results. Although no statistically significant differences were detected between participating and non-participating schools at the baseline of the study [9], analyses of the individual-level attrition across waves have shown that men, participants whose parents did not have tertiary education, and those with two parents born abroad were more likely to drop out after the first wave [38]. Another limitation of this study is the difficulty in establishing the precise direction of the relationship between educational attainment and mental health outcomes, although the variables were measured at different time points. While lower educational attainment may contribute to the development of depressive and anxiety symptoms, it is also possible that pre-existing mental health challenges, such as internalising disorders, influenced participants’ ability to complete their upper secondary education. As highlighted in previous research, mental health problems and educational outcomes often have a reciprocal relationship, with mental health issues both resulting from and contributing to school dropout [4,39]. This bidirectional dynamic complicates the interpretation of causal pathways in the observed associations. Even though the results of this study remained robust when accounting for prior psychosomatic complaints, future longitudinal studies are needed to substantiate and further disentangle this relationship. Another limitation concerns our operationalisation of immigrant background. We used three broad categories, with relatively small numbers in the ‘born in Sweden, both parents born abroad’ and ‘born abroad’ groups, which precluded consideration of specific countries of birth. Given the significant interaction between immigrant background and upper secondary diploma in relation to depression and anxiety co-occurrence, future research should examine more detailed subgroups to assess whether the observed differences are meaningful or due to chance. A final limitation that should be noted is the paucity of studies examining the psychometric properties of the PHQ-4 among young adults, particularly in Sweden.

To gain a deeper understanding of the mechanisms linking educational trajectories and mental health in young adults, further research – including qualitative studies – is needed to explore the subjective experiences of those navigating different educational pathways or experiencing school dropout, and how these experiences may differentially influence various mental health outcomes.

Addressing school dropout in Sweden requires re-engagement programmes for early school leavers, better alignment of vocational training with labour market needs, and the promotion of alternative pathways to education or employment. Such initiatives could enhance opportunities for stable employment and skill development, reducing stress and hopelessness associated with depression and improving mental health outcomes for those with lower educational attainment.

Conclusions

This study highlights the critical role of education in shaping mental health among emerging adults in Sweden. Not completing an upper secondary school diploma was consistently associated with elevated risks of the most severe outcomes; that is, severe symptoms (vs. normal/mild) and co-occurring depression and anxiety symptoms (vs. no symptoms), underscoring the mental health implications of early educational pathways. Given that emerging adulthood is a particularly sensitive period for mental health, initiatives that promote school completion and re-engagement hold significant potential to enhance public health and support successful transitions into adulthood.

Supplemental Material

sj-docx-1-sjp-10.1177_14034948261447060 – Supplemental material for Upper secondary school diploma and mental health in emerging adulthood: examining the severity and co-occurrence of depression and anxiety symptoms

Supplemental material, sj-docx-1-sjp-10.1177_14034948261447060 for Upper secondary school diploma and mental health in emerging adulthood: examining the severity and co-occurrence of depression and anxiety symptoms by Maria Granvik Saminathen, Sara Brolin Låftman and Viveca Östberg in Scandinavian Journal of Public Health

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study was funded by the Swedish Research Council for Health, Working Life and Welfare (Forte) (grants no. 2021−00537; 2022−01050). Open access funding provided by Stockholm University.

ORCID iD

Sara Brolin Låftman

Supplemental material

Supplemental material for this article is available online.

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