Nearly 1.2 billion people worldwide suffer from mental health disorders

The article, published in The Lancet—one of the most influential medical journals—is part of the Global Burden of Disease (GBD) project, which compares the impact of diseases worldwide. Its goal is to estimate the true burden of mental disorders and their evolution since 1990, not only in terms of how many people suffer from them, but also how they affect their lives. To do so, it integrates data from multiple sources and uses indicators such as years lived with disability (YLDs) and disability-adjusted life years (DALYs), offering a more comprehensive view of their impact. This approach is particularly relevant in a context where mental health remains underfunded, despite its significant social impact.

The results show that the burden is very high: in 2023, an estimated 1.17 billion cases and 171 million DALYs were recorded. Mental disorders are the leading cause of disability and the fifth leading cause of total disease burden globally. Depression and anxiety account for a large part of the impact, while schizophrenia stands out for its severity. Furthermore, a significant increase is observed in late adolescence and early adulthood, underscoring the importance of prevention and early intervention.

However, these data should be interpreted with caution. The observed increase may be due to multiple factors, such as demographic changes, improved detection, or the impact of COVID-19, and not necessarily to a real increase in cases. Added to this are significant methodological limitations, such as the lack of data in some countries, differences in the quality of sources, and the predominant use of information from high-income contexts. Therefore, although the study is key to guiding public policy, its results must be contextualized before being applied to specific situations.

Does the press release accurately reflect the study?

“The key data points are accurately reported: the 1.17 billion people with a mental disorder in 2023, the prominent role of anxiety and depression, differences by sex and age, and the warning about limited access to treatment. There are, however, some simplifications that warrant clarification: the release states that mental disorders account for “about 6% of all DALYs,” which is correct, but it fails to mention perhaps the most striking finding of the study: that in 1990, mental disorders ranked 12th in the global DALY rankings, and by 2023 they had risen to 5th place. That jump in the ranking is one of the most significant findings and deserves explicit mention. Also omitted from the article is the fact that anxiety disorders surpassed depression in burden for the first time in 2023, in part because they resolve spontaneously less frequently.”

Is the study of high quality?

“This is the most comprehensive global disease burden analysis available. The GBD 2023 covers 204 countries and territories, incorporated more than 5,000 new epidemiological data points, and has updated and improved its Bayesian modeling statistical tools compared to previous versions. The estimates include uncertainty intervals, which provide transparency regarding their reliability. It is an internationally recognized reference study, with independent funding (Gates Foundation, Queensland Health, and the University of Queensland) and no involvement of the funders in the analysis or interpretation.”

How does this study fit with existing evidence?

“It reinforces and updates previous evidence. The most recent comparable estimate by the same authors was from GBD 2019 (published in 2022). This new analysis incorporates the effects of the COVID-19 pandemic, which caused rates of depression and anxiety to skyrocket, especially in 2020–2021. It confirms already known trends (a higher burden among adult women, higher prevalence of neurodevelopmental disorders among male children and adolescents) and quantifies them more precisely. The finding that mental disorders are now the leading cause of years lived with disability (YLDs) globally is consistent with what other sources, such as the WHO’s 2022 World Mental Health Report, had been pointing out.”

Have confounding factors been taken into account? Are there significant limitations?

“The authors themselves are very transparent about the limitations, which is a sign of rigor. The most relevant ones are:

• Uneven geographic coverage: 75 countries (mostly low- and middle-income) lack their own data, which requires extrapolation using models. Estimates for those regions should be interpreted with caution.
• Data mostly pre-pandemic: most diagnostic surveys are from before 2019, which limits the ability to accurately capture recent trends.
• Diagnostic definitions: the study relies primarily on DSM-IV-TR criteria, which do not always translate well across cultures. Many measurement instruments have not been validated cross-culturally.
• Substance use disorders excluded: the analysis does not include alcohol or drugs, which frequently co-occur with mental disorders. This underestimates the total burden addressed by mental health systems.
• Does not capture all attributable mortality: suicide is classified in another GBD category, so the lethal impact of mental disorders is underestimated.”

What are the real-world implications?

“They are very significant. The study shows that mental disorders are now the leading cause of disability worldwide and that the gap between need and treatment remains enormous: only about 9% of people with depression or anxiety receive minimally adequate care. In low-income countries, that percentage may be less than 5%. The peak burden among 15- to 19-year-olds indicates that early interventions (school programs, screening in primary care, support for families) are indispensable. The fact that even countries with advanced health systems have failed to reduce the burden suggests that the problem cannot be solved by clinical resources alone: systemic changes are needed to address social determinants such as violence, inequality, or social isolation.

The main finding of this study is the combination of a growing burden (peaking in the adolescent population) and an insufficient therapeutic response, where barely 9% of those with depression receive adequate treatment. The data serve as an unequivocal wake-up call for governments to act with policies for early prevention, care tailored to young people and women, and real, coordinated investment in mental health.

When scientists speak of a disease’s “burden,” they are not referring only to how many people suffer from it, but to how much real harm it causes in people’s lives. It is a way of measuring collective suffering: how many years of healthy life are lost because someone cannot work, socialize, or simply live normally due to their illness. In the case of mental disorders, that harm comes from living for years or decades with constant anxiety, with depression that prevents one from getting out of bed in the morning, or with schizophrenia that completely isolates the person suffering from it. This study shows that mental disorders are now the leading cause of disability worldwide (or, in other words, that no other illness limits the daily lives of so many people on the planet more, even if it is not the one that kills the most directly).

Spain allocates less than 7% of its healthcare budget to mental health, and waiting lists to see a psychologist or psychiatrist in the public healthcare system are measured in months. It is not surprising that only one in ten patients with depression receives adequate treatment globally when, in our own system, mental health care remains, in practice, a privilege reserved for those who can afford it.

The new GBD 2023 analysis published in The Lancet provides a comprehensive overview of global mental health. The press release accurately reflects the key findings: around 1.17 billion people suffered from a mental disorder in 2023, with particularly marked increases in anxiety and depression, and an impact that already accounts for 6.1% of the total burden of disease and is the leading cause of years lived with disability.

The study is methodologically sound: it incorporates more than 5,000 new data points, applies advanced Bayesian meta-regression, updates diagnostic definitions and models the effect of COVID-19. Its conclusions are well supported by the data and are consistent with the accumulated evidence of recent years.

Such global analyses also have limitations that must be taken into account when interpreting certain differences between regions or countries. Data gaps persist in many low- and middle-income countries, as do potential self-reporting biases and diagnostic differences between regions, and it is difficult to fully capture complex social factors or the indirect mortality associated with mental disorders. The authors acknowledge these limitations and apply bias corrections, but they remain significant when interpreting subtle trends between countries.

The study sends a clear message about the need for more decisive action. We are facing a growing and unequal crisis. The higher rates among women and the peak burden in adolescence call for gender- and age-sensitive responses, with early prevention, early detection in schools, and tiered care in primary and community settings.

Public health prevalence studies like this one involve a host of decisions—both big and small—that must be made in order to draw overarching conclusions from previous research conducted using methods that are not always fully comparable. One can read them by focusing on their shortcomings (an approach I do not share) or by considering what we can learn from them and what assurances the authors provide.

As for what we can learn, the data are clear. Mental health problems are becoming increasingly common. This aligns with previous findings. It is yet another point in a pattern that has been clear for some time, with the advantage of being the most up-to-date and employing the most sophisticated analytical techniques currently available. These increases are not seen across all disorders but are concentrated in anxiety, depression, eating disorders, and autism. The press release perhaps highlights the data that most strikingly illustrates this pattern: the change between 1990 and 2023 in the total number of people worldwide living with a mental health condition. When one takes into account the change in the Earth’s population over these more than thirty years and changes in, for example, the distribution of age pyramids, the increase remains, admittedly, very substantial.

The research team clearly seeks to account for and neutralize, as much as possible, any factors that might be skewing these results. They detail their decisions regarding data collection and analysis and justify them. If the question is whether the study is free of limitations, the answer here (and in almost any study we can think of) is no; if the question is whether they did the best they could with the available data and whether there are reasons to trust these estimates, I believe the answer is yes.

Among the limitations, I would point out two. On the one hand, one inherent to this type of mental health research. A possible analogy would be trying to estimate how many tall (or short) people there are in the world. The answer to this is inseparable from where we set the thresholds, and these will always be somewhat arbitrary. Something similar happens with mental health. In contrast, when assessing deaths, there is less uncertainty regarding who is classified as deceased and who is not. That said, the authors adhere to the cutoff points agreed upon by the scientific community. On the other hand, the need to expand research in this field is clear. The uncertainty intervals for some specific results are relatively wide in some cases, reflecting that more data would be needed to achieve more refined estimates.

The press release itself indirectly highlights why mental health disorders, despite their prevalence and rising trend, remain relatively neglected public health issues. They are more prevalent among women and minors. These are not the groups that typically drive public policy. What is clear is that the notion that mental health disorders “have nothing to do with me or anyone around me” is an idea that is becoming increasingly unfounded.

In principle, this article is an excellent piece of work in which a large number of researchers and data agencies from around the world have collaborated, grouped within the GBD organization. The summary or press release also reflects the fundamental aspects of the article. It should be considered that, although the figures may seem very exaggerated, they are realistic. The changes over these 30 years being compared may be due to improvements in living conditions, but also to the fact that more diagnoses are now made and people make greater use of healthcare and psychological services. First comes survival, then mental health. However, statistically they accurately reflect the changes in recent decades and the differences between men and women, and between different geographical areas. It is also worth highlighting the data tables, which allow for comparisons and show the mean and the range (standard deviation), since there can be many differences between countries. They group them by large areas, but even so there can be significant differences between one country and its neighbor. What is particularly valuable about the article is the calculations they have made regarding the burdens represented by these mental health problems, reflected in the parameters of YLD (estimated years lived with disability), YLL (estimated years of life lost due to disability), and especially DALY (estimated years of life lost adjusted for disability), since some conditions may lead to higher suicide rates or premature deaths. These parameters provide policymakers with arguments about what could truly be saved if there were prevention programs and proper mental health care. Just one caution: the figures appear in American numerical notation, so when they refer to 1.17 billion people, they actually mean 1,170,000,000 people. In other words, out of the estimated global population of 8.396 billion, 1.17 billion would have mental health problems—that is, 13.93%. Presented this way, it may not seem quite as alarming. It should also be noted that the authors have focused on the most fundamental and severe mental health problems, leaving out many other issues that also appear in healthcare and psychological services. A recommendation for journalists: when extracting data from an article like this, with figures and population percentages, try to apply them to your own environment, using something close and understandable. For example, how many people with these problems (anxiety, depression, dysthymia, eating disorders, schizophrenia, behavioral disorders, etc.) would there be in the city of Madrid? About 498,330 people with mental health problems. Are they adequately cared for in Madrid? Are there enough facilities? Are there enough professionals?