SUMMARYCurrent understanding of psychosis development is relevant to patients' clinical outcomes in mental health services as a whole, given that psychotic symptoms can be a feature of many different diagnoses at different stages of life. Understanding the risk factors helps clinicians to contemplate primary, secondary and tertiary preventive strategies that it may be possible to implement. In this second article of a three-part series, the psychosis risk timeline is again considered, here focusing on risk factors more likely to be encountered during later childhood, adolescence and adulthood. These include environmental factors, substance misuse, and social and psychopathological aspects.LEARNING OBJECTIVES:After reading this article you will be able to: •understanding the range of risk factors for development of psychotic symptoms in young people and adults•understand in particular the association between trauma/abuse and subsequent psychosis•appreciate current evidence for the nature and strength of the link between substance misuse and psychosis.DECLARATION OF INTEREST:None.

SUMMARYPsychosis is a complex presentation with a wide range of factors contributing to its development, biological and environmental. Psychosis is a feature present in a variety of psychiatric disorders. It is important for clinicians to keep up to date with evidence regarding current understanding of the reasons psychosis may occur. Furthermore, it is necessary to find clinical utility from this knowledge so that effective primary, secondary and tertiary preventative strategies can be considered. This article is the first of a three-part series that examines contemporary knowledge of risk factors for psychosis and presents an overview of current explanations. The articles focus on the psychosis risk timeline, which gives a structure within which to consider key aspects of risk likely to affect people at different stages of life. In this first article, early life is discussed. It covers elements that contribute in the prenatal and early childhood period and includes genetic, nutritional and infective risk factors.LEARNING OBJECTIVESAfter reading this article you will be able to: •give an up-to-date overview of psychosis risk factors that can affect early life•describe some important genetic risk factors•understand more about the role of environmental factors such as nutrition and infection.DECLARATION OF INTERESTNone.

SUMMARYObesity and depression are conditions that have been linked through a great number of interesting mechanisms. To fully understand the implications of treatment choices it is necessary to continue to investigate the physiology of these two conditions. By examining the background of these problems and considering factors such as stress response, neurological change and systemic inflammation, we propose a cycle linking depression and obesity. With reference to this cycle, we discuss management options, focusing particularly on prescribing choices and current guidelines. An assessment of the medication options is provided demonstrating that prescribing choices can have a significant impact on ongoing physical health. The aim of this discussion is to raise awareness of current research and progress and to see whether the cycle of depression and obesity can be broken.LEARNING OBJECTIVES•Update knowledge of the mechanisms linking depression and obesity•Understand the impact of medication on the cycle linking the two•Consider how we can improve outcomes for patients with depression and/or obesityDECLARATION OF INTERESTNone.

SUMMARYPsychosis is a recognised feature of several psychiatric disorders and it causes patients significant distress and morbidity. It is therefore important to keep knowledge of possible risk factors for psychosis up to date and to have an overview model on which further learning can be structured. This article concludes a three-part series. It gives a review of evidence regarding common pathways by which many risk factors come together to influence the development of psychosis and finalises our suggested overview model, a psychosis risk timeline. The three primary pathways considered are based on the major themes identified in this narrative review of recent literature and they focus on neurological, neurochemical and inflammatory changes. We link each back to the factors discussed in the first and second parts of this series that alter psychosis risk through different mechanisms and at different stages throughout life. We then consider and summarise key aspects of this complex topic with the aim of providing current and future clinicians with a model on which to build their knowledge and begin to access and understand current psychosis research and implications for future preventive work.LEARNING OBJECTIVESAfter reading this article you will be able to: •give an overview of common pathways thought to link identified risk factors with psychosis development•understand neurochemical, neurostructural and inflammatory changes associated with psychosis•demonstrate increased knowledge of possible preventive strategies.DECLARATION OF INTERESTNone.

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