It's estimated that over one billion people globally have a mental, neurodevelopment or substance use disorder.


Despite being critical to overall wellbeing and physical health, diagnoses and furthermore, treatment or support, remain much lower than this estimate. In our entries on Mental Health and Substance Use we give an extensive overview of the global data on prevalence, disease burden, mortality and drivers of this group of disorders. The purpose of this blog post is to provide a shortened synthesis of 5 headline facts on global mental health.


1. Global statistics on mental health are poorly defined, measured, and understood


The true prevalence of mental health disorders globally remains poorly understood. Diagnosis statistics alone would not bring us close to the true figure - mental health is typically underreported, and under-diagnosed. If relying on mental health diagnoses alone, prevalence figures would be likely to reflect healthcare spending (which allows for more focus on mental health disorders) rather than giving a representative perspective on differences between countries; high-income countries would likely show significantly higher prevalence as a result of more diagnoses.


What makes such metrics even more challenging is the spectrum of mental health disorders can be broad. Mental health can incorporate a range of different but sometimes connected disorders such as depression, anxiety, bipolar, eating disorders, schizophrenia, and alcohol and drug use disorders. Many known sources - for example, the World Health Organization (WHO) - often do not measure global prevalence across individual mental health disorders beyond depression and substance use.


The data presented in our entries is published by the Institute of Health Metrics & Evaluation (IHME), Global Burden of Disease study. It's based on a combination of sources, including medical and national records, epidemiological data, survey data, and meta-regression models.


The data presented therefore offers an estimate (rather than official diagnosis) of mental health prevalence based on medical, epidemiological data, surveys and meta-regression modelling.


2. Mental & substance use disorders are common: every 5th or 6th person experiences one


Around 1-in-6 people globally (15-20 percent) have one or more mental or substance use disorders. Globally, this means over one billion people in 2016 experienced one. The largest number of people had an anxiety disorder, estimated at around 4 percent of the population. Given the known underreporting and poor data coverage of mental health across most countries (but especially within lower-income nations), we may even consider this a minimum estimate.


In this chart we show the share of the population with a mental health or substance use disorder. By clicking on a given country you can view how this has changed from 1990 through to 2016.



3. Prevalence of mental health disorders has not significantly increased


Many (myself included) have the perception that mental health issues have been increasing significantly in recent years. The data by the IHME that we have does, in general, not support this conclusion. The prevalence of mental health and substance use disorders is approximately the same as 26 years ago. This is shown in the chart below.


Although this remains true across most countries, ages, and specific mental health disorders, there are some examples where we have seen change in recent years. In the United States, for example, we see a slow but steady rise of depression in teenagers. It is also true that the prevalence of substance use disorders (the most notable example being rates of drug overdoses in the United States) has been increasing in some countries in recent years.


This, of course, does not mean mental health disorders are any less pressing. Their prevalence remains high, even if they are not increasingly significantly. In fact, as we make progress in combating other health aspects, mental health will become increasingly important in overall health burden on relative terms. As a share of total disease burden, mental health and substance use disorders are increasing, even if not in absolute terms.



4. Mental health disorders are more common in women


Mental health and substance use disorders can be common in both men and women. However, when we look at particular mental health or substance use disorders, we tend to find somewhat consistent gender patterns. Most disorders classified within mental health — that is depression, anxiety, bipolar and eating disorders - are more common in women than men. This pattern appears to hold true across most (in some cases all) countries.


The chart below shows the estimated share of males versus females with depression. Since all countries lie below the grey line, the prevalence is estimated to be higher in women than in men. This is also true for anxiety disordersbipolar disorder, and eating disorders. The gender balance for schizophrenia is more varied; in most countries there is a slightly higher prevalence in men, however this is not consistent across all countries.


The opposite is true of substance use disorders - as we describe in a separate blog post on the prevalence of substance disorders, across almost every country alcohol and other drug dependency is higher in men than women.


5. Education & employment are strongly linked to mental health


The risk factors for mental health and substance use disorders are complex. It is rarely the case that a mental health disorder can be attributed to a single factor or cause. As we discuss in detail in our entry on Mental Health, this group of disorders typically result from the interaction of individual attributes, social variables and environmental factors. Not only are these hard to directly identify, but also change and evolve throughout our life-course.


We must therefore be cautious when attempting to imply strong relationships between risk factors and mental health disorders. Nonetheless, there are a number of environmental, social and economic scenarios that appear to relate to the prevalence of mental health disorders. Level of education appears to have an important link to depression prevalence; but even stronger than this is our status of employment.


In the chart below we see the self-reported prevalence of depression in adults aged 25-64 years old, differentiated by the highest attained education level and status of employment (which we discuss further in our entry). Here 'active' implies 'actively looking for work', and 'total' is inclusive of those employed, actively looking for work and also those who are unemployed. This data is available for OECD countries only; you can view these using the "change country" in the bottom-left corner of the interactive chart.


Overall we see that depression tends to be lowest amongst groups who have undertaken tertiary (university or college) education. This is largely consistent across countries, but also across employment categories. In contrast, depression prevalence is typically highest in those who did not undertake upper secondary education. But, importantly, this gap between educational levels appears to close - and in some cases, disappear - when we consider only those who are employed. Rates of depression in those with below upper secondary levels of education that are employed are comparable to those of other educational levels.


A range of studies have also shown a strong correlation between unemployment (as well as job insecurity) and increased risk of depressive symptoms.