A large and neglected problem
In this shallow post, we consider the burden of the most common mental disorders, depression and anxiety. We note that this is only a subset of all mental health problems - there is some further information in this article from Our World In Data.
The 2017 Global Burden of Disease (GBD) report estimated that depression affects approximately 300 million people annually, while anxiety afflicts another 300 million. For comparison, the report estimated that malaria affects 146 million people and a 2018 World Bank report estimated that there are 650 million people living on less than $1.90 a day.
In a survey in the US, it is estimated that 1 in 3 people will suffer from a mental health disorder at some point over the course of their life. In England, one adult in every three households is estimated to be affected by a mental health disorder . It is common to believe that mental health problems are a ‘first-world problem’. Although mental health disorders are still significantly under-reported, particularly in lower-income countries, the data suggests that common mental disorders are highly prevalent globally. As can be seen in this visualisation, depression and anxiety between them account for nearly 3% of the global burden of disease (taking account of both morbidity - poor health - and mortality) and 8% of years lived in poor health.
Comparing rates of mental illness over time is difficult - are people suffering more or just reporting existing suffering. Nevertheless, severe mental illnesses seem to be on the rise. As one example, in the UK, the proportion of those reporting severe symptoms of common mental disorders has risen 34.7% between 1993 and 2014 (from 6.9% to 9.3% of the population). It’s unlikely this is solely due to increased reporting: an American birth cohort analysis running from 1938 to 2010 found large increases in all psychopathologies after using standard methods to control for possible increases in reporting. The number of people in extreme poverty is thankfully falling: it was nearly 1.9 billion in 1990 and was about 650 million in 2018.
As well as considering the health data, we can also study the effects of mental health problems on people’s happiness. In a recent analysis of self-reported happiness scores, the World Happiness Report evaluated how well poverty, lack of education, unemployment, being single, physical health (N.B. not just malaria) and mental health explain misery, where ‘misery’ here refers to those reporting the lowest happiness scores, roughly the bottom 10%. Happiness is typically measured by asking people about their life satisfaction, i.e. “Overall, how satisfied do you feel with your life nowadays on a scale of 0 - 10?”. They found mental illness was the biggest cause of misery overall (i.e. it accounts for the largest proportion of those in the miserable category). This is represented in figure 1 below.
Three of the surveyed countries were developed (UK, USA, Australia) and one was not (Indonesia), but in each country emotional problems were the biggest cause of misery. Interestingly, mental illness was still the biggest cause of lost happiness if we look at the non-miserable part of the population too.
A neglected problem
One third of Lower and Middle Income Countries do not have a designated mental health budget, and for those that do the average expenditure is 0.5% of their total health budget. In such countries, the treatment gap for mental health (i.e. the number who don’t get treatment as a percentage of those who need it) is 76-85%. A Centre for Global Development report describes mental illness as a “truly neglected area of global health policy”. What this implies is that there may be many high-impact ways to improve mental illness that are not (yet) being pursued.
 GBD 2017 Disease and Injury Incidence and Prevalence Collaborators, Spencer L, Degu Abate, Kalkidan Hassen Abate, Solomon M Abay, Cristiana Abbafati, Nooshin Abbasi, Hedayat Abbastabar, et al. 2018. “Global, Regional, and National Incidence, Prevalence, and Years Lived with Disability for 354 Diseases and Injuries for 195 Countries and Territories, 1990-2017: A Systematic Analysis for the Global Burden of Disease Study 2017.” Lancet (London, England) 392(10159), 1789–1858.
 World Bank. (2015). “World Bank Forecasts Global Poverty to Fall Below 10% for First Time; Major Hurdles Remain in Goal to End Poverty by 2030.”
 Kessler et al. (2005). “Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication.” Archives of general psychiatry 62.6: 617-627.
 Adult Psychiatric Morbidity in England - 2007, Results of a household survey.
 Steel et al. (2014). “The global prevalence of common mental disorders: a systematic review and meta-analysis 1980–2013.” International journal of epidemiology, 43(2), 476-493.
 Hidaka, B. H. (2012). “Depression as a Disease of Modernity: Explanations for Increasing Prevalence,” Journal of Affective Disorders, 140(3), 205–14.
 NHS Digital, “Adult Psychiatric Morbidity Survey: Survey of Mental Health and Wellbeing, England, 2014,” 2016.
 Twenge, J. M. et al. (2010). “Birth Cohort Increases in Psychopathology among Young Americans, 1938–2007: A Cross-Temporal Meta-Analysis of the MMPI.” Clinical Psychology Review, 30(2), 145–54.
 World Bank report (2018).
 Helliwell, J.F., Layard, R. and Sachs, J. (2017). World Happiness Report 2017, Chapter 5 (Sustainable Development Solutions Network). See also Fleche, S. and Layard, R. (2017). “Do More of Those in Misery Suffer from Poverty, Unemployment or Mental Illness?,” Kyklos, 70(1), 27–41.
 Shekhar Saxena et al. (2007). “WHO’s Assessment Instrument for Mental Health Systems: Collecting Essential Information for Policy and Service Delivery.” Psychiatric Services, 58(6), 816–21.
 WHO, Mental Health Atlas 2011 (World Health Organization, 2011).
 Victoria de Menil, “Missed Opportunities in Global Health: Identifying New Strategies to Improve Mental Health in LMICs,” 2015.