Jones et al's review of the assessment and management of the neuropsychiatric manifestations of Parkinson's disease serves as a practical guide to clinicians. This commentary outlines some of the underlying neuroscience and psychological sequelae of this range of conditions, offering a takeaway message to the clinician with an interest in Parkinson's neuropsychiatry.

There is considerable work being carried out in neuroscientific laboratories to delineate the mechanisms underlying single-gene disorders, particularly those related to intellectual disability and autism spectrum disorder. Many clinicians will have little if any direct experience of this type of work and so find the procedures and terminology difficult to understand. This article describes some of the laboratory techniques used and their increasing relevance to clinical practice. It is pitched for clinicians with little or no laboratory science background.

The professional regulatory cases of the psychiatrist Dr Richard Pool and the neuropathologist Dr Waney Squier have given rise to concerns among expert psychiatric witnesses, and indeed medical experts in general. Here we restate the law on expert evidence with particular reference to the judgment of the Supreme Court in the case of Kennedy v Cordia. We emphasise that Pool does not change the law regarding ‘what is expertise’; in particular, the case does not establish restrictive, status-based tests governing the admissibility of expert evidence such as according to whether an expert psychiatric witness has undergone higher training, is on the specialist register as a specialist in a particular field or is a consultant. Rather, expertise continues to be legally defined in terms of a combination of qualification, knowledge and experience. Crucially, the test of medical expertise in legal proceedings is a legal test and not one determined within a medical paradigm.

Addiction is a global health problem with a chronic relapsing nature for which there are few treatment options. In the past few decades, neuroimaging has allowed us to better understand the neurobiology of addiction. Functional neuroimaging paradigms have been developed to probe the neural circuits underlying addiction, including reward, inhibitory control, stress, emotional processing and learning/memory networks. Functional neuroimaging has also been used to provide biological support for the benefits of psychosocial and pharmacological interventions, although evidence remains limited and often inconclusive in this area, which may contribute to the variability in treatment efficacy. In this article, we discuss the changing definitions and clinical criteria that describe and classify addictive disorders. Using examples from functional neuroimaging studies we summarise the neurobiological mechanisms that underpin drug use, dependence, tolerance, withdrawal and relapse. We discuss the links between functional neuroimaging and treatment, outline clinical management in the UK and give an overview of future directions in research and addiction services.

Training in neuroscience is vital to the future of psychiatry as a medical specialty. Trainees and trainers alike demonstrate a desire to keep up to date with developments in the associated scientific fields. Neuroscience increasingly underpins clinical assessments, treatment options and patients’ expectations. Psychiatry training in the UK can embrace neuroscience at many levels, from discussing patient presentations with supervisors, to teaching programmes supported by the Royal College of Psychiatrists’ activities. Although challenges remain, neuroscience literacy enhances the specialty and will improve patient care.

Neurosurgery for mental disorder (NMD) is currently performed in the UK for cases of severe depressive disorder and obsessive–compulsive disorder refractory to treatment, under stringent regulations as set out under the Mental Health Act 1983. These surgical procedures appear to be effective for a proportion of individuals in this particularly treatment-resistant cohort. The two ablative procedures currently in use in the UK are anterior cingulotomy (ACING) and anterior capsulotomy (ACAPS). After briefly outlining these procedures, their evidence base and how they compare with other neurosurgical procedures, we suggest two ways in which they could be enhanced in terms of precision, namely the use of stereotactic (Gamma Knife®) radiosurgery guided by magnetic resonance imaging as well as a detailed and expanded standardised psychopathological and neuropsychological assessment both before and after surgery. The latter should involve extended long-term follow-up. We then reflect on how such psychopathological and neuropsychological assessments could help to understand why and how these procedures relieve patients’ suffering and distress.

Clinical neuromodulation began in psychiatry with electroconvulsive therapy (ECT), but in recent years several new techniques have been developed: repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), vagal nerve stimulation (VNS), trigeminal nerve stimulation (TNS) and deep brain stimulation (DBS). Each works in a different way, although the principle remains to effect therapeutic change through physically modifying brain activity. Their use in different clinical groups varies between techniques, as does their underlying evidence base. Most support currently exists for rTMS, with a more modest, but growing database for tDCS. Understandably, but problematically, most research in the other techniques has, to date, been in unmasked open trials. This article describes the mechanism of action and current evidence base for each technique, and notes the challenges facing future work in this potentially important field and new clinical avenue.