Time to Change (TTC) is the largest-ever programme in England designed to reduce stigma and discrimination against people with mental health disorders. The TTC evaluation partner is the Institute of Psychiatry at King's College London. We give an overview of the TTC programme 2007-2011 and describe how it was evaluated, by introducing the seven interrelated papers in this supplement, which, taken together, describe a complex series of social interventions using a research design of hitherto unparalleled detail and comprehensiveness.

It is now known that the onset of severe and recurring mental health problems begins for the most part before the age of 25: this provides a clear focus for preventive strategies and public mental health that are a feature of many health policy frameworks. The present distinction between child and adolescent mental health services and adult services at 16 or 18 does not fit easily with these data and the now well-documented problems of transition suggest that a fundamental review of services for young people is overdue. This supplement provides an overview of the epidemiological, conceptual and service structures for young people with emergent and existing mental health problems, and asks the question, ‘How should we design services for young people to promote prevention and service engagement, and to improve outcomes?’

Although the corrosive effect of mental ill health on human health and happiness has long been recognised, it is only relatively recently that mental illness has been acknowledged as one of the major threats to economic productivity worldwide. This is because the major mental disorders most commonly have their onset during adolescence and early adulthood, and therefore have a disproportionate impact on the most productive decades of life. With the costs associated with mental ill health estimated to double over the next two decades, a greater emphasis on prevention and early intervention has become even more imperative. Although prevention largely remains aspirational for many reasons, early intervention is well within our current reach and offers the potential to significantly reduce the impact of mental ill health on our health, happiness and prosperity in the immediate future.

Multimorbidity - the co-occurrence of two or more long-term conditions in an individual - is highly relevant to psychiatry. Changes to training and a more integrated model of psychiatric and physical healthcare are needed in the future if we are to improve the long-term health of our patients.

This evaluation of the Time to Change anti-stigma campaign in England represents a milestone in international stigma research. While showing some positive outcomes, the overall picture is mixed and falls short of the wholesale shift in attitudes that is needed. A new approach is proposed for the coming decades.

Genome-wide association studies (GWAS) have been the focus of considerable effort in psychiatry. These efforts have markedly increased knowledge of the genetic basis of psychiatric disorders, and yielded empirical data on genetic architecture critical to addressing long-standing debates in the field. There is a now a clear path to increased knowledge of the ‘parts lists’ for these disorders.

The study of age at onset of mental health disorders is technically and conceptually difficult. It is important to consider these age distributions in order to understand causes and mechanisms of illness and to intervene at an appropriate juncture for primary and secondary prevention. This article reviews some of the approaches to studying age at onset, sets out the evidence to support the assertion that adult mental disorders begin in adolescence, and finds that perhaps half of all adult mental health disorders have begun by the teenage years. The paper then discusses whether this fits what is known about the developmental neurobiology of the brain and introduces the implications for mental health services.

We propose a new model for geriatric psychiatry to help meet the needs of a rapidly growing population of older adults. This positive old age psychiatry would focus on recovery, promotion of successful ageing, neuroplasticity, prevention, and interventions to enhance positive psychological traits such as resilience, social engagement and wisdom.

Recruitment into psychiatry is perceived as problematic in the UK but the paper by Goldacre and colleagues in this issue of the Journal shows that recruitment of new UK graduates has altered little over 35 years. Sources of psychiatry's malaise should be sought in its changing focus and the quality, rather than quantity, of its recruits.