Thirty-year trends of anxiety disorders among adolescents based on the 2019 Global Burden of Disease Study

Data source

Data on adolescents’ anxiety disorder estimates were obtained from the GBD, which adheres to the Guidelines for Accurate and Transparent Health Estimates Reporting.25 The GBD database provides a tool to quantify health loss attributable to various diseases, injuries and risk factors so that health systems can be improved and disparities can be eliminated. Decision makers can use the tools provided by GBD to compare the impacts of different diseases and make informed decisions accordingly. The database captures premature death and disability from 370 diseases and injuries in 204 countries and territories, by age and sex, from 1990 to the present. Some of the GBD data sources are publicly available, published in studies or shared on the web by organisations like WHO and countries like Brazil. Other sources are shared by partners or through our network of over 3000 collaborators, and the context of data collection across different countries and organisations. Comprehensive descriptions of each analytical component of GBD are available on the Global Health website (http://ghdx.healthdata.org).26

The GBD Study estimates incidence, prevalence, years of life lost (YLLs), years of life lived with disability (YLDs), DALYs for anxiety disorders and groups of risk factors at the global level, regionally and nationally. YLLs were estimated using standardised approaches of data identification and extraction. Cause-specific YLDs were calculated by multiplying sequela-level prevalence with corresponding disability weights that were derived from population and internet surveys of more than 60 000 persons and adjusted for comorbidity through microsimulation.27 28 DALYs are the sum of YLDs and YLLs and are used to measure the comprehensive health status of a population for a given location, sex, year and age combination.29 Because anxiety disorders were not recognised as causes of death, YLLs were not estimated, and YLDs approximated DALYs. To distinguish the differences in DALYs across regions, we selected the DALY rate (per 100 000) from the GBD data.

Country-level variables

We obtained country-level data on the ESG Index,30 healthcare access within the mental sector (psychiatrists, psychologists and social workers),31 healthcare index and QoL.32

The ESG Index covers 183 countries and territories and encompasses three subindexes (environment, human rights, and health and safety) based on 65 variables to measure ESG risk exposure. Country scores are presented on a 0–100 scale, where 0 corresponds to the lowest risk and 100 to the highest risk. Adolescent mental health varies across nations due to differences in national policies regarding environment, human rights and security.33 Adolescents in countries without conflicts face lower risks of anxiety, while those in countries with strong human rights policies receive greater attention and protection.34 Therefore, our study selected the ESG Index, which reflects a nation’s environment, human rights, and health and safety. As a comprehensive indicator, the ESG Index can capture the multiple impacts of various factors on adolescent anxiety at a national level, assisting professionals in developing and implementing effective corporate social responsibility policies to reduce anxiety risks.

Healthcare access includes the number of psychiatrists, psychologists, nurses and social workers working in the mental health sector per 100 000 population. The QoL Index is an estimation of overall QoL by using an empirical formula that takes into account the Purchasing Power Index (higher index signifies better economic level), Pollution Index (lower index indicates less pollution), house price to income ratio (lower ratio suggests lower house price burden), Cost of Living Index (lower index implies lower living cost), Safety Index (higher index signifies safer environment), Healthcare Index (higher index indicates better health resources and medicine), Traffic Commute Time Index (lower index indicates shorter transport time) and Climate Index (higher index suggests better weather conducive to comfortable living). More QoL Index details can be found in https://www.numbeo.com/quality-of-life/rankings_by_country.jsp. The flowchart for data inclusion is shown in figure 1.

Analysis

We extracted incidence and DALYs, calculated the age-standardised incidence rates (ASIRs), and estimated the annual percentage change (APC) in anxiety disorders among children and adolescents aged 10–19 years in 204 countries from 1990 to 2019. The ASIR and estimated APC were used to quantify the incidence trends of anxiety disorders. The ASIR of anxiety disorders was used to compare the incidence of anxiety disorders in different countries or different historical periods in the same region. The method used to calculate ASIR has been reported previously.35 The estimated APC, a widely used measure of the ASIR trend over a specific time interval, describes the overall rates of changes in anxiety disorders per year in the selected time period. In the current study, it was designed to indicate the overall trend (increasing/decreasing) among different regions worldwide, which could provide an overall figure of anxiety disorders globally and identify the regions with relatively high increasing/decreasing rates. It was estimated by the loglinear regression model: y = b₀ + b₁x + e, where y=ln (rate), x=calendar year, b₀=intercept and e=error. The estimated APC was calculated as 100×(exp(β)−1), and its 95% confidence interval (CI) was obtained from a linear regression model.35 When the estimated APC 95% CIs are both ≤0, the ASIR is considered to be decreasing.36 Associations between the incidence rate and the abovementioned country-level variables were tested by Pearson’s correlation.

All statistical analyses were conducted using Microsoft Excel (V.16.63.1) and R (V.3.6.3). The significant level was set as α<0.05.

Incidence of anxiety disorders

Globally, there were an estimated 787 million cases of anxiety disorders in 1990 and 932 million cases in 2019, representing a 18.42% increase. The highest increase occurred in Equatorial Guinea (290.72%), followed by Qatar (274.64%) and Afghanistan (250.14%). The number of incident cases of anxiety disorders decreased from 1990 to 2019 in 70 countries, mostly in Bosnia and Herzegovina (−53.46%), followed by Georgia (−52.57%) and Lithuania (−50.34%) (online supplemental table S1). Incident case refers to the number of newly diagnosed cases of a particular disease that occur within a specified period of time. Incident cases can be used to identify trends, assess the burden of a disease and evaluate the effectiveness of prevention and control measures. Incidence refers to the probability of developing a disease or condition within a specific population and time frame. Incidence rates are typically expressed as a percentage or ratio (eg, per 100 000 people). Incident cases and incidence are closely related concepts but focus on different aspects of disease occurrence. Incident cases refer to the number of new cases within a specified period, while incidence refers to the overall probability of developing a disease within a specific population and time frame.

The supplemental tables show the ASIR, DALY rate and estimated APC (incidence and DALYs) of anxiety disorders worldwide in adolescents in 1990 and 2019 across various countries and territories. Figure 2A and figure 2B show the ASIR of anxiety disorders worldwide in adolescents in 1990 and 2019. The global ASIR of anxiety disorders fell from 744.91 (95% uncertainty interval (UI): 744.39 to 745.43) per 100 000 in 1990 to 739.29 (95% UI: 738.82 to 739.76) per 100 000 in 2019. The ASIR of anxiety disorders in the 204 analysed countries and regions varied considerably in both 1990 (figure 2A) and 2019 (figure 2B). In 1990, Portugal had the highest ASIR of anxiety disorders (1582.24 per 100 000), followed by Norway (1508.62 per 100 000) and Iran (1497.29 per 100 000), while Uzbekistan (435.27 per 100 000), Kyrgyzstan (439.39 per 100 000) and Kazakhstan (447.72 per 100 000) had the lowest ASIR. In 2019, Portugal maintained the highest ASIR of anxiety disorders (1602.32 per 100 000), followed by Iran (1560.69 per 100 000) and Ireland (1503.45 per 100 000), while Uzbekistan (435.94 per 100 000), Kyrgyzstan (440.51 per 100 000) and Kazakhstan (451.30 per 100 000) reported the lowest ASIR (online supplemental table S2).

Figure 3A visualises the estimated APC (incidence) of anxiety disorders worldwide among adolescents. The global estimated APC was −0.02 (95% CI: −0.01 to −0.04) from 1990 to 2019. The increase in ASIR across the 204 countries and regions was most pronounced in Mexico (estimated APC: 1.00, 95% CI: 0.65 to 1.35), followed by Ireland (estimated APC: 0.65, 95% CI: 0.40 to 0.90) and Lebanon (estimated APC: 0.57, 95% CI: 0.38 to 0.76). Conversely, the decrease in ASIR was most pronounced in Colombia (estimated APC: −0.39, 95% CI: −0.08 to −0.70), followed by Taiwan, China (estimated APC: −0.36, 95% CI: −0.28 to −0.43) and Japan (estimated APC: −0.34, 95% CI: −0.31 to −0.38) (online supplemental table S3).

Global burden of anxiety disorders

Globally, anxiety disorders accounted for a DALY rate of 391.39 (95% UI: 391.01 to 391.76) in 1990 and 380.62 (95% UI: 380.28 to 380.96) in 2019.

In 1990, among 204 countries and regions, Portugal had the highest age-standardised DALY rate (976.29, 95% UI: 961.52 to 991.24), followed by Norway (875.49) and Iran (843.13), while India (211.83), Uzbekistan (215.69) and Nepal (217.43) had relatively low DALY rates. In 2019, Portugal maintained the highest DALY rate (1001.71), followed by Ireland (897.80) and Iran (873.64). India (212.09), Uzbekistan (216.87) and Kyrgyzstan (218.99) had the lowest DALY rates (online supplemental table S4). The largest increase in DALYs was reported in Equatorial Guinea (300.31%), followed by Qatar (272.22%) and Afghanistan (250.03%). The DALYs of anxiety disorders decreased from 1990 to 2019 in 74 countries, with the most significant declines seen in Georgia (−52.97%), followed by Bosnia and Herzegovina (−52.92%) and Taiwan, China (−51.76%) (online supplemental table S5).

Figure 3B presents the estimated APC (DALYs) of anxiety disorders in adolescents worldwide. The increase in DALYs across the 204 countries and regions was most pronounced in Ireland (estimated APC: 1.07, 95% CI: 0.62 to 1.52), followed by Lebanon (estimated APC: 0.89, 95% CI: 0.61 to 1.17) and Mexico (estimated APC: 0.83, 95% CI: 0.38 to 1.29). The decrease in DALYs was most pronounced in Taiwan, China (estimated APC: −0.56, 95% CI: −0.45 to −0.68), followed by Finland (estimated APC: −0.51, 95% CI: −0.31 to −0.72) and Colombia (estimated APC: −0.44, 95% CI: −0.09 to −0.79) (online supplemental table S6).

Associations among incidence rates, DALYs and country-level variables

Table 1 shows the sociodemographic and health-related variables across countries and territories. Norway, Netherlands, France and Monaco have the most psychiatrists, (48.04 per 100 000), psychologists (123.50 per 100 000), nurses (98.02 per 100 000) and social workers (102.60 per 100 000) in the mental health sector, respectively. Ethiopia has the highest ESG Index (62.28). Portugal has the highest Healthcare Index (80.30) and Netherlands has the highest QoL Index (196.70).

Table 2 shows the association between incidence rates and DALYs among different countries. Apart from the correlations among covariables, the incidence rate showed statistical significance with the number of psychiatrists and psychologists. The disease burden of adolescents was positively correlated with the number of psychiatrists, psychologists and nurses in mental health departments and QoL, and the correlation coefficients were 0.58, 0.67, 0.43 and 0.53, respectively. However, there was no significant association between adolescents’ anxiety disorders and the number of social workers, the ESG Index and the Healthcare Index.

Main findings

Using the available data and analytical framework of GBD 2019, we estimated a significant increase in the number of cases and a decrease in ASIR, estimated APC and burden of anxiety disorders among adolescents over the past three decades. Specifically, the DALY rate of adolescent anxiety disorders fell from 391.39 to 380.62. This finding is in line with previous research, which indicated a decrease in the global DALY rate of depression in the general population, from 588.6 in 1990 to 577.7 in 2017.37 Several factors may contribute to these changes, including sociodemographic and economic environments. For example, effective intervention packages for mental disorders exist in most regions with a high Sociodemographic Index. These interventions have the potential to reduce the burden due to mental disorders by alleviating symptoms, promoting remission or mitigating mortality risk.38 In some regions, unstable environments such as conflict and war may impede the diagnosis and treatment of anxiety disorders in adolescents. Furthermore, increasing acceptance and awareness of mental health issues may encourage adolescents to seek mental health services more readily, contributing to the observed decline in burden.39 Therefore, implementing effective intervention strategies, maintaining a stable social environment and promoting mental health awareness play a significant role in reducing the burden of anxiety disorders.

Our findings indicated that the ASIR of anxiety disorders among adolescents was 7.39 per 1000, a higher figure compared with the 5.8 per 10006 reported for the general population in a previous study. Additionally, our study revealed a global estimated APC for anxiety disorders in adolescents of −0.02, which is lower than the 0.02 estimated APC reported in previous research.6 Compared with prior research, we focus on the special group of adolescents and anxiety disorders, while previous studies paid more attention to the most common mental health conditions, such as depression. Anxiety disorders are also at the top of the list of mental health problems that are easily overlooked. Also, previous studies focused on the overall situation of the whole population, but the stressors and coping methods of adolescents’ anxiety are usually different from those of adults, which are determined by the traits of adolescence.

The ASIRs of anxiety disorders were highest in Portugal (1990 and 2019) and lowest in Uzbekistan (1990 and 2019) among the 204 analysed countries and regions. Mexico had the largest annualised growth of ASIR from 1990 to 2019. The highest DALY was observed in Portugal, while India had the lowest. The largest increase in DALY was observed in Ireland (estimated APC: 1.07) in 1990 and 2019. A systematic understanding of the exact change pattern of anxiety disorder burden could help policymakers allocate limited medical resources rationally and develop adapted prevention and treatment strategies.

The incidence rates of adolescent anxiety disorders were highest in developed countries in northern Europe (Portugal, Norway and Ireland) and Asia (Iran) in both 1990 and 2019. The incidence rates were lowest in developing Asian countries (Uzbekistan, Kyrgyzstan and Kazakhstan), which is consistent with global anxiety surveys and research.40 The higher incidence rates observed in northern Europe may be attributed partly to increasing mental health literacy, less stigma41 42 and improved access to mental health services.43 For instance, the population of Póvoa de Varzim in northern Portugal exhibited above-average levels of mental health literacy, with stigma decreasing as mental health literacy increased.40 Furthermore, some studies suggest that the geographical phenomena of cold weather and lack of sunlight in winter may exacerbate anxiety problems.44 Regarding Iran, evidence suggests that individuals with lower socioeconomic status have worse health outcomes.45 Illiteracy and low levels of education marginalise people, limiting their access to available mental health services and hindering the achievement of important community goals, such as promoting health and accessing social support and healthcare services.46 47

Asian countries such as Uzbekistan, Kyrgyzstan and Kazakhstan have shown lower incidence rates of anxiety disorders. One possible explanation for this is that the cultural pathways to developing such disorders differ between Asian and Western people. For example, from the perspective of cultural values and social expectations, Asian cultures tend to place a greater emphasis on collectivism, harmony and respect for authority.48 These cultural norms can lead to higher levels of stress and anxiety when individuals struggle to meet these expectations. In contrast, Western cultures emphasise individualism, self-expression and personal freedom, which may contribute to a more open approach to discussing mental health issues.49 As a result, Asian and Western countries showed different levels and incidences of anxiety disorders.

The extent to which specific factors contribute to a diagnosis may be partly influenced by an individual’s identification with one culture over another.50 Additionally, the low incidence of anxiety disorders among adolescents in certain regions could be attributed to conflicts in the Central Asia region, where conflicts between countries result in a neglect of adolescents’ mental health.51 The study revealed that anxiety rates rise in conflict areas24 52 and that children who have experienced war are more susceptible to anxiety. However, obtaining precise data from these areas can be challenging.34

The ASIR increased the most in Mexico, followed by Ireland and Lebanon. The present results also showed that the changing trends of anxiety disorder burden (DALYs) vary considerably among countries, with the highest growth rate of DALY in Ireland, followed by Lebanon and Mexico. The ASIR increased significantly in the regions with a high Sociodemographic Index, as well as in high-income Latin America (ie, Mexico). The rapid increases in the ASIR of anxiety disorders in these regions could be due to high levels of economic development, education and social pressure leading to more concern about adolescent anxiety disorders.

Ireland’s noteworthy changes in ASIR and DALY trends could be linked to its high-level economic conditions, social pressures, cultural environment and high self-awareness of anxiety symptoms. Experts generally agree that educational pressure or social media are common sources of anxiety among adolescents with high levels of anxiety. The pursuit of academic excellence among young students may stem from broader social and cultural norms. Additionally, the rapid dissemination of unfounded rumours and gossip through digital channels can exacerbate anxiety in young people.53 In Lebanon, cultural factors may contribute to the increasing adolescent anxiety.54 Lebanon is considered a more collectivistic society compared with many Western societies, favouring behaviours characterised by withdrawal and modesty.48 Individuals in such societies tend to be highly conscious of the presence of others that operate on high moral ground.55 Excessive focus on societal norms and expectations can cultivate feelings of falling short and contribute to anxiety.55 Furthermore, political instability and warfare have led to deaths, casualties and displacements in Lebanon, which have had a profound psychological impact on civilians. According to the study, the 30-day prevalence of psychiatric disorders was 26.1%, with 13.1% of Lebanese adolescents experiencing anxiety.56

The socioeconomic and cultural contextual information in the mentioned countries is shown in online supplemental table S7. The socioeconomic and cultural level of European countries is relatively high, and the per capita GDP (US$40 755) and school enrolment rate (80%) are higher than the global average (GDP: US$12 647.5; school enrolment rate: 42%), while the social, economic and cultural level of Asia is relatively low.

Regarding the relationship between health service resources and anxiety disorders, the number of mental health nurses was positively associated with anxiety disorder burden. This correlation suggests that enhanced access to healthcare resources may facilitate the identification of adolescent anxiety disorders. This contrasts with previous research indicating that insufficient health service utilisation contributes to an increased incidence of anxiety disorders.57 Additionally, the positive correlation between disease burden and QoL confirms that mental health issues become more pronounced when fundamental living conditions are met and addressed. This is also in line with Maslow’s hierarchy of needs theory,58 which posits that lower-level basic needs must be met first before higher-level needs (such as psychological needs) can be fulfilled. These findings suggest that anxiety disorders among adolescents may be underestimated, particularly in low-income or low-QoL countries.

Limitations

This study analyses the temporal and spatial trends in adolescents’ burden of anxiety disorders. However, it is also subject to some limitations. First, the data were obtained from the GBD database, in which anxiety disorders are classified into panic disorder, agoraphobia, specific phobia, social phobia, obsessive-compulsive disorder, post-traumatic stress disorder and generalised anxiety disorder. Our analysis was based on this classification method without further subdivision, limiting our ability to assess the prevalence of specific anxiety disorders among adolescents. Second, it is inevitable that some microstates (eg, San Marino) may have missing data, potentially introducing deviations in the results. Third, there may be potential biases due to discrepancies in the mental health service data available, which were collected from different years and might not have been uniformly obtained across geographical regions. This variation may weaken the influence of some factors that change over time on anxiety. Future research could explore specific subtypes of anxiety disorders or investigate the effectiveness of interventions in different cultural contexts. Local health authorities could establish and implement standardised common protocols for microstate data collection. These results may contribute to a more nuanced and comprehensive understanding of anxiety disorders, allowing for targeted interventions and policies to improve mental health outcomes among adolescents globally.

Implications

Despite these limitations, our study offers valuable insights into the policy implications concerning countries or territories grappling with a heavy burden of anxiety disorders among adolescents. This knowledge can inform future efforts aimed at reducing incidence rates. For example, in developed countries, there is a pressing need to prioritise adolescent anxiety disorders and implement timely screening and appropriate intervention. Also, our study highlights the underestimation of anxiety disorders in conflict-ridden countries and regions. Policymakers and practitioners should consider the impact of diverse cultural backgrounds and countries’ characteristics when designing interventions for adolescent anxiety disorder. For instance, adolescents in Asian countries may be more susceptible to anxiety resulting from unfulfilled societal expectations, whereas adolescents in developed countries like Ireland are more likely to experience anxiety disorders due to academic pressure or the influence of social media. Also, our findings suggest that the Centres for Disease Control and Prevention in low-income and middle-income countries should popularise mental health knowledge and raise awareness of anxiety disorders.