The legal decision on whether a defendant can fairly take part in a criminal trial in England and Wales is currently based on the leading case of R v Pritchard (1836), which despite subsequent case law updates does not embrace the concept of mental capacity or effectively identify defendants who are unable to meaningfully participate. Further to an extensive consultation process, the Law Commission published recommendations for reform in 2016, with a proposed new test of capacity to participate effectively in a trial and detailed suggestions for statutory reform of court procedures for managing defendants found unable to participate. Here we review the proposals and consider practical implications and suggestions regarding their implementation.

Nitrous oxide (N2O) misuse is widespread in the UK. Although it is well-known that it can cause devastating myeloneuropathy, psychiatric presentations are poorly described. There is little understanding of who it affects, how it presents, its mechanism of action and principles of treatment. We begin this article with a case study. We then review the literature to help psychiatrists understand this area and deal with this increasing problem, and make diagnosis and treatment recommendations. We describe a diagnostic pentad of weakness, numbness, paraesthesia, psychosis and cognitive impairment to alert clinicians to the need to urgently treat these patients. Nitrous oxide misuse is a pending neuropsychiatric emergency requiring urgent treatment with vitamin B12 to prevent potentially irreversible neurological and psychiatric symptoms.

The evidence base on the relationship between religion and mental health is growing rapidly, and we summarise the latest research on the topic. This includes studies on religious involvement and depression, bipolar disorder, suicide, post-traumatic stress disorder (PTSD), substance use disorders, personality disorder, chronic psychotic disorder, marital/family stability, social support and psychological well-being. We also review a relatively new topic in psychiatry, moral injury, which often accompanies PTSD and may interfere with its treatment. We describe a theoretical model that explains how religion might affect mental health and briefly discuss its applications in clinical practice, including a discussion of religiously integrated therapies for depression, anxiety and other emotional problems. Overall, studies indicate that religious involvement often serves as a powerful resource for patients, one that can be integrated into psychiatric care. At times, however, religion may impede or complicate treatment. This article will help clinicians determine, on the basis of the latest research, whether religion is an asset or a liability for a particular patient.

Comorbid anxiety symptoms are common in depression, and adding benzodiazepines to antidepressant treatment may seem a rational clinical solution. Benzodiazepines also have potential to reduce the initial anxiety that may be caused by early antidepressant treatment (owing to their inhibitory effect via GABAA receptor binding). This month's Cochrane Corner review examines the evidence behind combination treatment versus antidepressants alone in major depressive disorder, in terms of both the clinical and neuroscientific context. The review provides evidence that, in the first 4 weeks of treatment, additional medication with a benzodiazepine may lead to greater improvements than antidepressant alone on ratings of severity, response rates and remission rates for depression, but not on measures of anxiety.

Psychiatric assessments of adults involved in care proceedings can play a critical role in assisting the family court to resolve proceedings justly. To properly carry out this role, the psychiatric expert should have an up-to-date understanding of the wider context within which they are working. This article outlines the legal framework of care proceedings in England and Wales and summarises the key aspects of the process. The duties of the expert and how the expert is engaged are explained. Finally, guidance is presented on how the expert should approach questions that are commonly raised in these proceedings.

In an earlier article we reviewed the latest research on the relationship between religious involvement and mental health, the effects of religiosity on mental health and well-being over time and the impact of religious interventions. Here we focus on clinical applications that may be useful to psychiatrists and other mental health professionals. We discuss general clinical applications relevant to all patients (e.g. taking a spiritual history, supporting/encouraging religious beliefs, referring to clergy), violations of clinician–patient boundaries and the need to ensure that religious/spiritual interventions are patient-centred. We describe evidence-based religious interventions and how to identify appropriate patients for this approach. Finally, we explore situations in which religious beliefs and practices may be a problem, not a resource, and make recommendations on how to address such cases. Case vignettes illustrate clinical situations that mental health professionals are likely to encounter. Although the focus is on the North American context, we note how practice and culture in the UK may differ.

Patients with psychiatric illness present a unique challenge to clinicians: in contrast to the traditional medical model, in which patients are conceptualised as being stricken by a disease, patients with certain psychiatric illnesses may seem complicit in the illness. Questions of free will, choice and the role of the physician can cause clinicians to feel helpless, disinterested or even resentful. These tensions are a lasting legacy of centuries of mind–body dualism. Over the past several decades, modern tools have finally allowed us to break down this false dichotomy. Integrating a modern neuroscience perspective into practice allows clinicians to conceptualise individuals with psychiatric illness in a way that promotes empathy and enhances patient care. Specifically, a strong grasp of neuroscience prevents clinicians from falling into the trap in which behavioural aspects of a patient's presentation are perceived as being separate from the disease process. We demonstrate the value of incorporating neuroscience into a biopsychosocial formulation through the example of a ‘difficult patient’.

Alcohol use disorders (AUD) are common, particularly in patients attending mental health services. Clinicians are often hesitant to explore with patients their relationship with alcohol and the role that it has in their presenting complaint, despite being ideally placed to optimise on a ‘teachable moment’ and initiate treatment, where necessary. This article provides an overview of AUD and their identification and management options.

The World Health Organization's proposals in ICD-11, released for comment by member states in 2018, introduce for the first time in a major diagnostic system a distinction between post-traumatic stress disorder (PTSD) and complex post-traumatic stress disorder (CPTSD). This article sets the new diagnosis of CPTSD within the context of previous similar formulations, describes its definition and requirements, and reviews the evidence concerning its epidemiology, differential diagnosis, assessment and treatment.

Value-based healthcare holds great potential to transform healthcare globally. This commentary reviews the historical milestones in its evolution and raises critical questions regarding how it should proceed.

Despite the enormous amount of literature on medical care of older people, personality disorders in late life have been given little attention. Clinicians tend not to assign this diagnosis to older adults in view of limited research into, and therefore limited awareness of, this topic. This article aims to promote better understanding of this subject in view of the growing population of older people and hence an expected increase in the number of personality disorder cases.

The diagnostic status of ‘complex’ post-traumatic stress disorder (PTSD) remains controversial. The revisions to PTSD diagnostic criteria in ICD-11 and DSM-5 take opposing positions on how best to conceptualise post-traumatic presentations that include affect dysregulation, interpersonal difficulties and negative self-concept. ICD-11 carved out a separate category of complex PTSD (CPTSD) that is distinct from PTSD, whereas DSM-5 expanded PTSD to encompass such symptoms. Each approach carries problematic implications for clinical care. ICD-11 creates a dichotomy but the criteria themselves suggest a difference in severity rather than category. Furthermore, separating CPTSD perpetuates expectations that a ‘simple’ PTSD can be easily treated with brief trauma-focused therapy. DSM-5 complicates the PTSD diagnosis, but does not revise treatment recommendations. Both ICD and DSM need to recognise that most patients with PTSD do not reflect the clinical trial samples and do not fully recover with brief manualised therapies. Treatment guidelines should be developed that address the multiple needs and challenges of all patients with PTSD.

Religious concerns, manifested in thought and behaviour, have a complex, bidirectional and sometimes conceptually overlapping relationship with mental health and mental disorder. Psychiatry, concerning itself with what is measurable in research, and with the relief of distress in clinical practice, has a different perspective on these complex interrelationships than does theology or religion. That which is transcendent, and therefore not measurable, is often important to patients, and sometimes distress may (theologically) be a sign of human well-being. The giving of careful attention to transcendence and distress may variously be conceived of as prayer, religious coping or clinical care. Applications of research to clinical practice, addressing as they do a sensitive and controversial boundary between psychiatry and religion, must therefore be patient centred and culturally sensitive.

Second-generation antipsychotic medications (SGAs) have advanced the treatment of schizophrenia over the past 30 years. However, a number of potentially life-threatening cardiac side-effects associated with these treatments concern and can discourage prescribers from administering these evidence-based treatments. This review provides a practical, psychiatrist-oriented understanding of the relative frequencies, mechanisms, investigations and treatments associated with these cardiac toxicities. We aim to highlight that these are relatively rare complications of an effective class of drug and to promote the advantages of early involvement of cardiologists in the psychiatric multidisciplinary team to guide the investigation and management of these conditions.

Psychiatry intertwines mind and brain, sometimes in a strained marriage. Psychiatrists feel the criticism of a ‘narrow’ biological or medical (and medication) focus, and we are very aware of the limitations of all treatments and diagnostic systems. Many understandably move towards a more social approach, seeing individuals in their wider lives. But there are dangers in losing the brain, something unique to our specialty in the world of mental health. This reflective piece calls for us to rediscover the joy of the science of the brain, which augments, not conflicts with, psychosocial approaches.

This is an overview of epidemiology relevant to mental health problems in old age. We start by reviewing some basic terminology: the definitions of prevalence and incidence; the difference between descriptive and analytical epidemiology; the differences between study designs, including cross-sectional, case–control and cohort studies. We then cover the main epidemiological features of the major psychiatric diseases that affect older people (dementia and its different types, depression, late-onset schizophrenia, bipolar affective disorder, delirium, anxiety-related disorders, eating disorders, alcohol and substance misuse, personality disorders) and suicide.

We end with some descriptive statistics regarding quality of life in older people.

The authors summarise the evolving understanding of the neuropsychophysiology of chronic pain, including the relevance of adverse childhood experiences in facilitating it and similarities between the central physiology of chronic pain and opioid addiction. Emerging understanding highlights the importance of dopamine-expressing GABAergic neurons in the nucleus accumbens and suggests that D1 expression is associated with a sense of pleasure and approach behaviour and D2 with a sense of punishment and behavioural inhibition. Regulation of D1 and D2 expression may be mediated by nigrostriatal and medial frontal striatal pathways within the increasingly understood brain as a ‘predictive’ organ. The distinction between the predictive brain and personal ‘expectations’ and the importance of the latter for clinical outcomes are emphasised. The relevance of findings for possible future psychopharmacological treatment avenues is also presented.

Personality disorder is likely to be common in late life, but our ignorance is such that, at present, we can only speculate about its frequency and importance. The only firm evidence we have is that antisocial personality features tend to be attenuated in older age and obsessional and detached features accentuated. Differentiating personality change following organic disease from personality disorder requires more attention as it is important for good clinical management.

Shortcomings of randomised controlled clinical trials include their high cost, which often precludes very long-term studies and very large populations, and ethical constraints of randomisation. Observational studies are a valuable alternative and we outline their use in epidemiological research to study very long-term effects of lifestyle and medication on dementia, to explore (using Mendelian randomisation) the association between Alzheimer's dementia and individual traits, and to evaluate population-wide health inequalities and lifespan changes in risk factors for psychiatric illness.

Historically, Parkinson's disease was viewed as a motor disorder and it is only in recent years that the spectrum of non-motor disorders associated with the condition has been fully recognised. There is a broad scope of neuropsychiatric manifestations, including depression, anxiety, apathy, psychosis and cognitive impairment. Patients are more predisposed to delirium, and Parkinson's disease treatments give rise to specific syndromes, including impulse control disorders, dopamine agonist withdrawal syndrome and dopamine dysregulation syndrome. This article gives a broad overview of the spectrum of these conditions, describes the association with severity of Parkinson's disease and the degree to which dopaminergic degeneration and/or treatment influence symptoms. We highlight useful assessment scales that inform diagnosis and current treatment strategies to ameliorate these troublesome symptoms, which frequently negatively affect quality of life.