Earlier this year, former ODI director Kevin Watkins said, ‘we need to do more on mental health’.  He’s right: in ODI’s 56-year history, we’ve done just a handful of research projects on the subject. And we’re not alone in this in the development sector.

Donor governments give just $134 million in development assistance to mental health, shared between 148 developing countries. That means each population receives a fraction of funding. And there’s little to no contribution from charities or big-name development donors. The result is millions of people (almost 90% worldwide) not getting treatment.

Stigma and lack of understanding about the multiple types of mental, neurological and substance use disorders are just a couple of the reasons why mental health hasn’t gone mainstream. And there are some misguided assumptions that get in the way of the development sector investing in mental health.

Here we debunk just a few:

1. Mental wellbeing is a health issue only

It’s not. Mental disorders – and the treatment gap – disproportionately affect the world’s poorest and most vulnerable citizens. Across the globe, the cost burden is shouldered by families and developing country governments – the groups least able to foot the bill.

As well as the moral and social arguments for tackling mental disorders, there are strong economic arguments. Mental disorders represent a huge cost to the global economy. Across the 36 largest countries in the world, more than 50 million years of work are lost to depression and anxiety disorders every year.

Mental health is in three of the Sustainable Development Goal targets. So if we’re to genuinely work towards the goal of ‘leaving no-one behind’, governments and donors have to start prioritising mental health.

2. It’s hard to measure progress in mental health

It’s not. The World Health Organization Mental Health Action Plan 2013-2020 sets out clear objectives for global mental health. Within these objectives are targets, and indicators by which to measure progress.  These targets operate at the global, country and programme level.

So for example, under the objective: ‘Provide comprehensive, integrated and responsive mental health and social care services in community-based settings’, one target is to increase service coverage for severe mental disorders by 20%, which can be measured by the number and proportion of persons with a severe mental disorder who received mental health care in the last year.

And there’s a baseline: in 2014, 171 countries reported against these indicators in the WHO Mental Health Atlas survey, providing data against which countries can measure progress towards the Action Plan objectives.

3. It’s expensive

It doesn’t have to be. In 2007, The Lancet estimated that the cost of scaling up a basic package of mental health care in low-income countries was just $2 per person per year.

And sustainable, cost-effective mental health care can be delivered through ‘task sharing’. This is where lay health workers – that is, health workers with no formal mental health accreditation – are trained to provide mental health support. Development programmes are demonstrating that this is working to fill the treatment gap (though ideally, this needs to happen alongside an increase in the number of trained mental health professionals).

It can also be inexpensively integrated into other development programmes, which brings us on to the fourth myth.

4. It’s not my job

It is. Some of the links between mental health and other development areas are obvious: suicide and agriculture; depression and forced immigration, post-natal depression and new-born and child health. Others may be less so.

But whatever the area you work in, there are plenty of case studies showing that adding a mental health component to development interventions can improve the success of these programmes. For example, the Friendship Bench in Zimbabwe trained lay health workers, known as ‘grandmothers’, to provide individual problem-solving therapy to HIV patients with depression. Not only did the project see a reduced incidence of suicide – high among those diagnosed with HIV – patients were also better at sticking to their treatment plans and taking their medication.

At the recent ‘Out of the Shadows’ meeting, Jim Yong Kim, President of the World Bank Group said, ‘[Mental health] is not just a public health issue – it’s a development issue. We need to act now.’ The call to arms is unequivocal. And the development sector needs to listen.