A large and neglected problem
The 2017 Global Burden of Disease (GBD) report estimated that depression affects approximately 300 million people annually, while anxiety afflicts another 300 million. By comparison, the report estimated that malaria affects 146 million people, while 2015 World Bank report estimated 702 million people living on less than $1.25 a day.
While poverty affects many more people than mental health, the share of the world population living in absolute poverty is falling rapidly: there were 1.76 billion in absolute poverty in 1999, a drop of about 1 billion people. By contrast, severe mental illnesses are 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.
Mental illness vs poverty
To properly assess scale we also need to know how much suffering each causes: if poverty makes people miserable but mental illnesses are only mildly bad, poverty will be larger in scale. 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%. 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. Of course, we may well expect poverty causes a larger amount of misery in countries even poorer than Indonesia - we’re not aware of an equivalent analysis of very poor countries - so there’s room to disagree about whether poverty or mental illness causes the most unhappiness worldwide.
For our purposes, it’s not essential to work out which of those two is bigger. The key point is that the worldwide scale of suffering caused by mental illness is huge, and at least of the same order of magnitude as poverty. It will almost inevitably increase, relative to poverty, over time.
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”.
Although we have shown that mental health is a large and neglected problem, it cannot be a priority if there are no effective treatments. The next article in this series discusses the different forms of treatment for mental health and their relative effectiveness.
 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.”
 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.
 Helliwell, J.F., Layard, R. and Sachs, J. (2017). World Happiness Report 2017, Chapter 5 (Sustainable Development Solutions Network)
 Ibid. Those interested in how life satisfaction (one of the components of what is sometimes called ‘subjective well-being’) is measured, and how reliable those measures are should see:
 Ibid. 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.
 Another approach would be to use health metrics. This is less useful than using happiness scores for two reasons. First, that only allows us to compare health states, and we want to able to compare health states to poverty, which we can do with happiness scores. Second, health metrics (DALYs and QALYs) reflect how people who have mostly never experienced these illnesses imagine they would feel if they did so. A better alternative is to measure directly how people actually feel when they actually do experience the illness. When QALYs have been compared to happiness scores, it was found the public hugely underestimated by how much mental pain (compared with physical pain) would reduce their satisfaction with life, as discussed by Dolan, P. and Metcalfe, R. (2012). “Valuing Health,” Medical Decision Making, 32(4), 578–82.
 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.