An old Danish proverb warns: ‘it is difficult to make predictions, especially about the future’ (Epstein, Reference Epstein2019, 219). Apart from the obvious constraint of a lack of data, there is always the temptation to replace predictions of what will happen with what one hopes will happen. Nevertheless trends from past events can be helpful when contemplating the future, and the recent Lancet Commission on Global Mental Health and Sustainable Development (Patel et al., Reference Patel, Saxena, Lund, Thornicroft, Baingana, Bolton, Chisholm, Collins, Cooper, Eaton, Herrman, Herzallah, Huang, Jordans, Kleinman, Medina-Mora, Morgan, Niaz, Omigbodun, Prince, Rahman, Saraceno, Sarkar, De Silva, Singh, Stein, Sunkel and UnUtzer2018b) highlighted key milestones on the journey of Global Mental Health so far. This editorial seeks to reflect on these milestones, and how they might inform possible future trends during the next ten years for the field of Global Mental Health.

The first milestone to mark this journey in the 21st century was the WHO World Health Report 2001, which for the first time focused on mental health under the banner of ‘New Understanding, New Hope’ and called on governments to give greater policy and funding priority to mental health (WHO, 2001). This was followed by the WHO Mental Health Policy and Service Guidance Package, which provided practical guidelines for countries to develop, implement and evaluate mental health policy and services (WHO, 2005). In 2007, the Lancet published its first series on Global Mental Health which reviewed the latest evidence on the burden of mental disorders and cost-effective treatment and prevention interventions, with a final article calling on countries, especially low- and middle-income countries (LMIC) to scale up mental health services (Lancet Global Mental Health Group, 2007). In the same year, the Movement for Global Mental Health was launched and the United Nations Convention on the Rights of Persons with Disabilities was signed, underlining the vital importance of the human rights of people living with mental illness and disabilities, and their central role in leading global advocacy efforts (United Nations, 2007). The following year saw the launch of the WHO mental health Gap Action Programme (mhGAP), including its flagship Intervention Guide to support the scale up of mental health care in primary care settings around the world (WHO, 2008). mhGAP has subsequently been implemented in over 100 countries. In 2011, a second Lancet series on Global Mental Health was published, along with the findings of a large international Delphi priority setting study, identifying the Grand Challenges in Global Mental Health research (Collins et al., Reference Collins, Patel, Joestl, March, Insel and Daar2011). These priorities have subsequently informed substantial mental health research funding and capacity building programmes in LMIC by a number of funding agencies including Grand Challenges Canada, the UK Department for International Development, the US National Institute of Mental Health, the Global Challenges Research Fund and the Wellcome Trust. In 2013, the WHO launched its Mental Health Action Plan, unanimously adopted by all countries in the World Health Assembly (WHO, 2013), and in 2015 the United Nations published the Sustainable Development Goals (SDGs), including mental health for the first time in the global development agenda (United Nations, 2015). In 2016, an historic meeting of the WHO and World Bank was convened titled ‘Out of the Shadows: making mental health a global development priority’, accompanied by new evidence on the return on investment for mental health care for depression and anxiety disorders (Chisholm et al., Reference Chisholm, Sweeny, Sheehan, Rasmussen, Smit, Cuijpers and Saxena2016) and cost-effective interventions (Patel et al., Reference Patel, Chisholm, Dua, Laxminarayan and Medina Mora2016). Finally, the Lancet Commission on Global Mental Health and Sustainable Development launched its findings at the first global mental health summit in 2018, and called for a reframing of mental health using more dimensional approaches, a convergence of diverse disciplinary research traditions, and the upholding of mental health as a fundamental human right (Patel et al., Reference Patel, Saxena, Lund, Thornicroft, Baingana, Bolton, Chisholm, Collins, Cooper, Eaton, Herrman, Herzallah, Huang, Jordans, Kleinman, Medina-Mora, Morgan, Niaz, Omigbodun, Prince, Rahman, Saraceno, Sarkar, De Silva, Singh, Stein, Sunkel and UnUtzer2018b).

From this brief review of the milestones, a number of trends from the past 19 years may provide clues for the future. First, we have seen a burgeoning of mental health research, and research capacity building programmes especially in LMIC. A systematic review published earlier this year found that the use of the term ‘global mental health’ increased from 12 published peer reviewed articles in 2007 to 114 articles in 2016, although the review highlights important gaps in the field (Misra et al., Reference Misra, Stevenson, Haroz, de Menil and Koenen2019). Mental health research in LMIC is increasingly attracting a rich and diverse range of disciplines including anthropology, economics, epidemiology, genetics, social sciences, psychiatry and psychology. Based on these trends and currently available research funding, it is likely that this research will continue to grow, and it is vital that previously neglected areas (e.g. child and adolescent mental health) are addressed. It is also vital that we move beyond dichotomising emic and etic approaches and move towards more integrative convergent and interdisciplinary models.

Second, at a policy level we have seen a growth in government commitment to mental health. For example, there has been a growth in the proportion of African countries with a mental health policy from less than 50% in 2001 to 72% in 2017 (WHO, 2017). However, these policy commitments have not translated substantially into financial commitments to scale up mental health care in most LMIC. In 2017 low-income countries spent US$0.02 per capita on mental health, compared to US$80.24 in high-income countries (WHO, 2017). And development assistance for mental health remains pitifully small. It is difficult to predict whether this trend is likely to change in the coming years, and increased investment is likely to required substantially increased advocacy efforts and compelling research evidence.

Third, we have seen an enormous growth in advocacy for human rights and support for the notion of mental health as a fundamental human right. Initiatives such as the WHO QualityRights programme have drawn attention to continuing widespread human rights abuses perpetrated against people living with mental illness in LMIC, and developed toolkits for protecting human rights and improving the quality of services in community and institutional settings. The Global Mental Health Peer network was launched in 2018 and signals a new era in global leadership by people with lived experience of mental illness, a trend which is likely to grow in the future.

Fourth, recent years have seen a growing awareness of the social determinants of mental health and a shift away from focusing on scaling up treatment, to addressing the social and economic drivers of population mental health through prevention and promotion interventions. The inclusion of mental health in the SDGs, and the potential for aligning SDG targets with the social determinants of mental health presents an exciting opportunity (Lund et al., Reference Lund, Brooke-Sumner, Baingana, Baron, Breuer, Chandra, Haushofer, Herrman, Jordans, Kieling, Medina-Mora, Morgan, Omigbodun, Tol, Patel and Saxena2018). Of interest is a few recent funding calls and discussion documents published by major research funders on evaluating interventions to address social determinants of mental health and the mechanisms by which such interventions might improve population mental health – potentially signalling some growth in future research in this area, especially in LMIC.

Fifth, the last 19 years have seen a massive proliferation in the use of digital technologies for training, decision support, data collection and direct interventions in mental health (Naslund et al., Reference Naslund, Aschbrenner, Araya, Marsch, Unutzer, Patel and Bartels2017). This is likely to grow significantly in the years to come as technologies continue to evolve rapidly, both as an opportunity for improved population surveillance and intervention, and as a potential threat to privacy and confidentiality.

Finally, and perhaps most soberingly, the last 19 years have seen a substantial growth in two major threats to population mental health, namely climate change and income inequality. Climate change threatens population mental health through a number of pathways, including exposure to climate related natural disasters, anxiety about the implications of climate change, increased prevalence of physical illness, such as vector-borne diseases which are associated with mental illness, and basic threats to the viability of human social structures, food networks and infrastructure. It is vital that global mental health researchers, advocates and clinicians throw their weight behind commitments to reduce carbon emissions and develop a sustainable path to a healthy planet. Income inequality has been shown in at least one meta-analysis to be associated with increased prevalence of depression, through a variety of national, district and individual level mechanisms (Patel et al., Reference Patel, Burns, Dhingra, Tarver, Kohrt and Lund2018a). Linking global challenges of mental health, climate change and income inequality will require a more integrated approach to development advocacy, and better coordinated, multi-sectoral action by governments and development agencies.

To conclude, a number of priorities can be identified for the next ten years. Renewed united global advocacy efforts are required to convince governments of the importance of mental health and the human and economic costs of doing nothing. We need to move from policy commitments to resource commitments and action, particularly for the most vulnerable: children, adolescents, older adults and those living with severe and disabling conditions. This requires an integrated approach to sustainable development, with mental health at the centre: both a means to sustainable development and a worthy goal in itself.

Further research is required in three key priority areas: (1) improved understanding of the aetiology of mental health conditions across the life course, particularly in critical developmental periods such as pregnancy, infancy, adolescence and old age; (2) intervention research on prevention and mental health promotion interventions, especially targeting the social determinants of mental health and (3) implementation science evaluating the scaling up of mental health care to larger populations, especially in community and primary care settings.