Over the last century, prevention has become an increasingly important part of modern healthcare. For example, the decline in infectious diseases is due more to preventive strategies such as immunisation and hygiene than to Alexander Fleming's discovery of penicillin. Life style changes and prophylactic medication have reduced coronary heart disease over the last decades. There is now an increased focus on how to prevent mental disorders.1

The arguments supporting a preventative approach to depression are compelling. While effective treatments for depression are available, the experience of a depressive illness is both distressing and associated with poorer physical health,2 occupational dysfunction3 and increased mortality.4 In most countries depression is usually treated by general practitioners, who do not feel sufficiently resourced to provide optimal treatment.5 Even in the unlikely event of optimal treatment being delivered to all affected patients, cost-effectiveness models suggest only 35–50% of the overall burden of illness would be alleviated.6

The standard …