Clinical depression is a chronic worldwide health problem affecting millions of people and approximately 13 per cent of the UK population. Researchers say that although it is a chronic and recurrent problem for many sufferers, little is known about what makes people vulnerable or resilient to the condition. Lead researcher, Andrew McIntosh, Professor of Biological Psychiatry at the University of Edinburgh, said: "For many people the symptom of low mood is the most understandable of reactions to loss or stress, yet we remain ignorant of its causes and mechanisms. This means that progress in discovering new and more effective treatments is slow. This Wellcome Trust grant will enable us to make significant progress with this common and disabling condition". The study - known as Stratifying Resilience and Depression Longitudinally (STRADL) - involves researchers from the University of Edinburgh's Division of Psychiatry, Centre for Cognitive Ageing and Cognitive Epidemiology (CCACE), Institute for Genetics and Molecular Medicine (IGMM) and brain imaging facilities in Edinburgh and at the University of Aberdeen.