One in five people will suffer from a major depressive disorder at some time in their lives. The World Health Organisation says it's the fourth biggest cause of ill health in the world and that by 2020 it will be the second biggest, just behind heart disease.
As well as its high incidence, depression can be a recurring, chronic condition. Recent research estimates that patients will experience an average of four major episodes of 20 weeks each during their lifetime. The favoured treatment for the past three decades has been a combination of medication and cognitive-behavioural therapy (CBT). Unlike traditional psychoanalysis, CBT therapists emphasise the present rather than early childhood. They argue that the past doesn't matter and, in any case, it may be impossible to get to the bottom of why you do what you do. The key, therefore, is to change the way you are now, to alter your thinking. In other words, depressives must choose to change.
Behaviour therapists have been fierce critics of what they see as the amazing flights of psychoanalytic fancy which are used to explain simple phobias or other clinical disorders. To ridicule psychoanalysts, therapists have been known to coach chronically mentally ill patients to perform simple actions and then watch with amusement as their colleagues concoct bizarre symbolic interpretations of behaviours with known and simple histories.
Now we appear to be on the cusp of yet another revolution in therapy. It hasn't yet been honoured with a formal name, but hinges on the buzz words "mindfulness and acceptance". This new perspective borrows hugely from Zen Buddhism, which teaches that each moment is complete in itself; that the world is perfect as it is.
As a result, Zen focuses on acceptance, validation and tolerance instead of change. In contrast to the experimental evidence required in psychology, it emphasises experiential evidence as a means of understanding the world.
Psychoanalysis focused on trying to understand; CBT insisted on change without deep analysis; now "mindfulness and acceptance" asks us to consider that our problems are rooted in our preoccupation with preoccupation.
It is remarkable how liberating it feels to be able to see that your thoughts are just thoughts; that they are not "you" or "reality". It can allow you to become more clear-sighted and have a greater sense that you are managing your life. Taking a step back from our thoughts can disconnect our emotional energy from our thinking. This seems to free us to be more creative by helping us understand the very process of being.
Whatever you think of Zen, any treatment which might reduce the high relapse rate of depression has to be worth a go. In the future we may come to see that before we had an effective treatment we blamed depression for being a stubbornly difficult disorder, when all along we should have been blaming the inadequate treatments we were using.
Dr Raj Persaud is Gresham professor for public understanding of psychiatry, and director of the Centre for Public Engagement, King's College London.
His latest book is The Motivated Mind (Bantam Press). Email: email@example.com