One of the demanding puzzles yet to solve in academia and beyond is the increasing burden of mental health problems globally.
Unfortunately, this is not new. Previous research and projections highlight that the prospect of mental disorders is daunting. For instance, the Global Burden of Disease Study in 2010 found increases in every metric used to measure mental health burden in the UK (Horowitz, 2013). In the same vein, mental and substance use disorders were reported as the leading cause of non-fatal illness worldwide (Horowitz, 2013). Even before the emergence of Covid-19 in 2020, depression, anxiety and suicide were leading causes of the global health burden (Santomauro et al., 2021; Fortgang & Nock, 2021).
Although the current data highlights the scale of the problem, until recently, there had not been a detailed investigation of the most up-to-date information on the prevalence and burden of mental disorders across the global population. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) addressed this gap in the literature, focusing on the global burden of 12 different mental disorders in 204 different countries between 1991 and 2019.
The GBD 2019 Mental Disorders Collaborators defined mental disorders according to the DSM-IV and ICD-10 to gather the epidemiological data needed for the analysis. Next, a systematic literature review was conducted with no language restrictions. The authors’ inclusion criteria for study selection were surveys reporting estimates of mental disorder prevalence, incidence, remission, or excess mortality. On the other hand, surveys that used non-probabilistic sampling or reported on population subgroups were excluded.
The collaborators also took estimates of the following statistical outcomes:
- Years lived with disability (YLD)
- Years of life lost (YLL)
- Disability-adjusted life years (DALY)
Years lived with disability (YLD) is a measure that reflects the impact that a disorder has on quality of life before it resolves or leads to death.
Years of life lost (YLL) is a measure of premature mortality. These are the years lost from the calculated life expectancy after dying from the disease.
A sum of the aforementioned measures equals disability-adjusted life years (DALYs). DALYs provide us with an estimate of how much burden does the disease provides to the population of interest. Simplified, it is analogous to dying one healthy year earlier than expected.
Taken together, the results of the analysis concluded that mental disorders increased by 48.1% between 1991 and 2019 (654.8 million cases to 970.1 million cases) respectively.
Years of life lost (YLL)
- Only the YLL of eating disorders was estimated by the authors. Eating disorders caused 318.3 deaths in 2019. These were mainly caused by Anorexia Nervosa, followed by Bulimia Nervosa.
Years lived with disability (YLD)
- 125.3 million YLD were caused by mental disorders – that is around 14.6% of global YLDs in 2019.
Disability-adjusted life years (DALY)
- Overall, males had 1,426.5 DALYs and females had 1,703.3 DALYs per 100,000.
- Unsurprisingly, depressive disorders had the largest proportion of DALYs, followed by anxiety disorders and finally schizophrenia.
- DALYs differed by age, sex and country.
- Higher DALY rates were reported in countries such as Australia or Brazil, whilst Southeast Asia and Central Asia had lower rates.
The puzzle, unfortunately, seems to have gotten harder to solve. The authors concluded that 1990 and 2019 had similar discrepancies in the global distribution and burden of mental disorders, yet, overall numbers, YLDs, YLL and DALYs have remained high. And, taking into account the exponential growth of the world’s population, this should be a cause for concern for scientists and political leaders worldwide.
Strengths and limitations
Overall, the insights gained from this study may be of assistance to both the scientific and political community, providing a strong case for increased mental health research, funding and policy change worldwide.
However, there are some limitations to consider. Firstly, although there was testing and adjustment for biases, a checklist such as the ROBINS-E or the CASP was not utilised. These could lead to evaluations that include irrelevant concepts or that are inconsistent from study to study, reducing its reliability.
It is unfortunate that the study only included YLLs for eating disorders. Considering the presence of DALYs across all year groups, it would have been useful to see the statistics of YLLs in different mental disorders. The authors said: “Deaths and YLLs could be calculated only for anorexia nervosa and bulimia nervosa, since these were the only mental disorders identified as underlying causes of death in GBD 2019.”
Moreover, since the study was limited to countries, it was not possible to observe the different burdens of mental disorders within countries. For instance, research has shown associations between the socio-ecological environment, urbanicity, and differing mental health prevalence (Gruebner et al., 2017). Therefore, categorising countries as regions, high income or low income may reduce the chance of developing specific interventions in specific locations within a country, as the needs of urban or rural areas within a country, for example, may vary.
Notwithstanding the above limitations, the study certainly adds to our understanding of global mental health and the challenges that lay ahead.
Implications for practice
This new evidence highlights how the current practices and policies worldwide are simply not enough to tackle this issue.
Implementation research should focus on mental health prevention. Currently, a gap exists between prevention research and implementation in services – joining the workforce and services could be vital to reducing this gap (Furber et al., 2015). If we can prevent mental health disorders, the burden will likely reduce. Similarly, funding needs to be allocated fairly worldwide, as low-income countries spend 0.5% of their budget on mental health compared to 5.1% in high-income countries (Vigo et al., 2019; Saxena, 2019). The allocation of funding must also heavily shift from aetiology of mental disorders to prevention, detection, and development, all of which get a mere 5% or less (Arsenault, 2019). Finally, policy changes need to be updated or developed, as some countries to date do not have mental health policies in place (Bughra et al., 2018).
The findings of this study will also be of interest to clinicians and mental health professionals. Firstly, although the findings illustrate that depression, anxiety, and schizophrenia had the largest DALYs, these rates differed by age, sex, and country. Therefore, clinicians should be encouraged to write contingency plans in their services based on the prevalence and burden of a disorder in their specific country. That way, clinicians could prepare for a sudden rise in cases of a specific disorder in their country, providing a plan of action to meet the potential increased demand. Secondly, the already enormous pressure on mental health services worldwide may increase, particularly with the effects of lockdown (Torjesen, 2020). This could increase the rates of burnout for clinicians as job control and the nature of the caseload are previously reported causes of this psychological syndrome (Yang & Hayes, 2020). Thus, greater efforts are needed to ensure that there is an increase in the amount of trained mental health professionals in the workforce to meet the demand of the increasing mental health burden. In addition, services such as the NHS Practitioner Health should be implemented worldwide, as these could have the ability to reduce mental health problems in practitioners (Simpson et al., 2021).
Effective and robust psychosocial interventions must be both accessible and affordable in different parts of the world. I have been fortunate to be able to access the services that I needed when mental health problems knocked on my door. Yet, others may not have the same luck as me. Mental health is a real global issue, in several countries, cultures, and locations. The only way we will eradicate mental health problems is by joining global efforts and finances towards meaningful and effective policies and interventions.
Statement of interests
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