Many manifestations of mental illness, risk factors, course and even response to treatment are shared by several diagnostic groups. For example, cognitive and social impairments are present to some degree in most DSM and ICD diagnostic groups. The idea that diagnostic boundaries of mental illness, including schizophrenia, have to be redefined is reinforced by recent findings indicating that on the one hand multiple genetic factors, each exerting a small effect, come together to manifest as schizophrenia, and on the other hand, depending on interaction with the environment, the same genetic variations can present as diverse clinical phenotypes. Rather than attempting to find a unitary biological explanation for a DSM construct of schizophrenia, it would be reasonable to deconstruct it into the most basic manifestations, some of which are common with other DSM constructs, such as cognitive or social impairment, and then investigate the biological substrate of these manifestations.

A more prominent role is needed for mental health interventions in global HIV/AIDS initiatives – such as the World Health Organization ‘3 by 5’ Initiative. Significant numbers of infected people have, or develop, mental health problems, and this often adversely impacts on HIV/AIDS treatment and adherence. Integrating psychiatric and psychosocial interventions should benefit both the mental and the physical health of people living with HIV/AIDS.

Autistic-spectrum disorder is approximately half as common as schizophrenia but its cause remains unknown. Recent studies have begun to clarify the underlying neuroanatomical abnormalities and brain-behaviour relationships in autism. In the past decade, great advances have been made in our understanding of the neurobiological basis of autism.

The hypothesis that chronic and long-term experience of ‘social defeat’ may increase the risk for schizophrenia is proposed. This increased risk may result from sensitisation of the mesolimbic dopamine system and/or increased baseline activity of this system. Data supporting the social defeat hypothesis are presented.

Depression remits and recurs, but among what proportion of the population? Retrospective surveys report the lifetime risk to be around 10%. A modelling study and two prospective studies concur that close to half the population can expect one or more episodes of depression in their lifetime.

Proteomics is the study of protein expression and function on a genome-wide scale and its application in psychiatric research is relatively new. As protein expression is the mediator of genetic vulnerabilities, it is critical that this area is explored further to increase our understanding of psychiatric disease and reveal potential new treatments.

Suicide is an important contributor to premature mortality accounting for over 800 000 deaths worldwide every year Environmental and genetic factors acting from before birth to old age affect an individual's risk of suicide. Risk is influenced not only by psychiatric illness and impulsive behaviour but also by factors such as the cultural acceptability of suicide, the ease of availability of lethal suicide methods, help-seeking behaviours in times of crisis and access to effective treatments following self-harm. Suicide prevention programmes might usefully focus on two discrete areas: the prevention of the psychiatric illnesses that precede suicide and tackling those risk factors particular to suicide such as media influences, help-seeking, the availability of methods and the medical management of self-harm.

Self-harm remains an important public health problem and two sets of clinical guidelines have been published recently. While these include elements of accepted good practice they are not evidence-based. Further research might concentrate on either very large trials of low-intensity interventions or smaller trials of longer-term psychological treatments. The current management of self-harm may be improved by shifting professionals' views, involving users in staff training, and changing service provision – perhaps moving from risk assessment to needs assessment.

International research has established that there is a strong genetically inherited contribution to attention-deficit hyperactivity disorder (ADHD) and the genetic mechanisms involved are being sought with considerable success. It is now established that certain alleles of the genes coding for the dopamine D4 receptor and the dopamine transporter occur more frequently in children with ADHD than in healthy controls, and we are finding other DNA changes associated with ADHD. A major challenge for the field now is to clarify how genetic susceptibility is translated into disorder by integrating the fields of quantitative and molecular genetics, neuropsychology and environmental risks.

Recent reports and guidelines that have an impact on the management of people with eating disorders are summarised. The core competencies of every psychiatrist should include: the ability to assess acute risk (including a medical evaluation) and long-term prognosis, and to know what treatments effectively address these needs.

Concerns about violent conduct of service users towards healthcare staff have prompted a ‘zero tolerance’ policy within the National Health Service. This policy specifically excludes users of mental health services. We attempt to challenge artificial distinctions between users of mental health and other services, and propose an ethical underpinning to the implementation of this policy.

Use of cost-effectiveness acceptability curves, as a method for summarising information on uncertainty cost-effectiveness, has become widespread within applied studies. This includes several studies in the mental health field. This editorial uses examples from recent papers to illustrate how cost effectiveness acceptability curves are constructed, what they represent and how they should be interpreted.