Insomnia is common, affecting approximately 10% of the population. In addition to night-time sleep difficulties, insomnia disorder requires the presence of concomitant daytime impacts, making it a 24-hour problem. It is not surprising, therefore, that insomnia disorder is associated with significant impacts to quality of life and economic costs. Many patients with insomnia also have comorbid physical and/or mental health disorders, and sometimes also other sleep disorders. This chapter reviews the key features, prevalence, and consequences of insomnia disorder, and provides background information to aid clinicians as they begin to think about formulating treatment approaches.

Among patients with mood disorders, suicidal thinking, planning, and acts are common, particularly during major depressive episodes or mixed episodes. In this chapter, the epidemiology and aetiology of suicidal behaviour in major depressive disorder and bipolar disorder are outlined, followed by the relevant risk factors, and risk assessment of suicide. Finally, the latest evidence on treatments is discussed from a pharmacological, psychological and physical perspective.

‘Psychotic disorders’ is an umbrella term for psychiatric conditions featuring psychosis, including mood disorders. Despite the prominence of psychotic symptoms across the psychotic spectrum, a distinction between schizophrenia and affective psychoses has been historically established. Findings from genetic studies support the aetiological overlap between affective and non-affective psychosis, although poor characterisation of the schizoaffective population still poses a challenge. Likewise, literature points to shared environmental risk factors between bipolar disorder and schizophrenia. Neuroimaging evidence suggest significant similarities in the pathophysiology of the brain between affective and non-affective psychosis. An overlap is also observed in other biological and behavioural illness markers, as well as in the pharmacotherapy of psychotic disorders. Current diagnostic entities may not accurately delineate the aetiology and pathophysiology of these conditions. Modern classification approaches, such as the RDoC framework, propose the adoption of aetiological factors and pathophysiological evidence to characterise patients, rather than categorical diagnoses based on symptoms.

Anxiety symptoms and anxiety disorders are common in community settings and primary and secondary medical care. Anxiety symptoms are often mild and only transient, but many people are troubled by severe symptoms that cause both considerable personal distress and a marked impairment in social and occupational function. The principal anxiety disorders are currently considered to comprise panic disorder, generalised anxiety disorder, social anxiety disorder, agoraphobia, specific phobias, separation anxiety disorder and selective mutism. Additional conditions (not considered further here) include substance/medication-induced anxiety disorder, anxiety disorder due to another medical condition, other specified anxiety disorder and unspecified anxiety disorder. Together, anxiety disorders constitute the most frequent mental disorders, with an estimated 12-month prevalence of approximately 10–14 per cent.

Although the societal impact of anxiety disorders is substantial, many of those who could benefit from psychological or pharmacological treatment are neither recognised nor treated. Recognition relies on maintaining a keen awareness of the psychological and physical symptoms of anxiety disorders, and accurate diagnosis rests on identifying the pathognomonic features of specific conditions.

This chapter presents a new, annotated translation of an unusual treatise, commonly known by the Latin name De fluviis, preserved among the works of Plutarch and probably written between AD 100 and 250. The chapter introduction discusses the work’s date and authorship; notes the author’s preference for stories about Greece and places to the east as far afield as India, as well as his tendency to misidentify his literary sources when he does not actually invent them; and explains the repetitive organization of its 25 sections. These offer mythological explanations (often erotic, homicidal, or suicidal) for changes of names in rivers and mountains, as shaped by the recurrent themes of retribution and vindication of those who suffer injustice. On a factual level, the geography is lamentable, but the author’s examples of stones and plants with miraculous properties—often related to the fates of the individuals in the stories, though sometimes to the intrinsic properties of the rivers they feature—are sometimes confirmed by other sources. Presumably ‘the author knew his audience’.

Psychosis is characterized by distortions in thinking (e.g. fixed, false beliefs), in perception (e.g. hearing voices or less commonly seeing things that are not there), emotions, language, sense of self and behaviour. Although it used to be thought that schizophrenia was a discrete entity, much recent evidence has shown that this is not so. Schizophrenia does not have clear boundaries; rather, it merges into schizoaffective disorder and bipolar disorder on the one hand and into schizotypal and paranoid personality on the other. It is best considered as the severe form of psychosis. The different psychotic disorders share some of the same risk factors and are sometimes associated with cognitive impairments, co-existing mental health conditions, substance misuse and physical health problems; the latter often develop over the course of the illness.

In this chapter, we review genetic and then environmental risk factors for psychosis. Much knowledge has accumulated regarding both in the last two decades. We now know that the aetiology of psychosis is multifactorial. Genetic and environmental factors occasionally act alone but usually in combination as well as operate at a number of levels and over time to influence an individual’s likelihood of developing psychotic symptoms.

Eating disorders are complex and serious illnesses that can result in physical and psychiatric comorbidities, medical emergencies and progressive health consequences. Although general psychiatrists may be called upon to assist in emergencies or differential diagnoses, training in this area has been limited. The author attempts to fill the gap by providing a summary of the most recent advances in the field of eating disorders in this chapter to help orient trainees and general psychiatrists. This chapter provides an overview of the most recent changes to the DSM-5 and ICD-11 diagnostic categories for eating disorders, as well as their epidemiology, aetiology and treatment, including the management of complications and life-threatening medical emergencies.

The chapter summarises recent advances in the genetic and neurobiological understanding of eating disorders, as well as emerging new research. These scientific advances have the potential to contribute to the development of new, more-effective eating disorder treatments in the future.

Neurodevelopmental disorders is an umbrella term that incorporates a range of conditions characterised by some form of disruption to ‘typical’ brain development. These disorders share aetiological pathways that have genetic, social and environmental risk factors. Neurodevelopmental disorders often have core features in common and they frequently co-occur. Long-term impairment is characteristic, although key features may vary over the life span. This chapter covers key aspects of the aetiology of neurodevelopmental disorders, in particular focusing on those found in forensic settings (such as autism spectrum disorder, intellectual disability, attention deficit and hyperactivity disorder and fetal alcohol spectrum disorder). The impact of genetic, social and environmental risk factors is considered. The chapter considers the aetiology of neurodevelopmental disorders as relevant to forensic settings.

Violent behaviour displayed by individuals with intellectual disability (ID) is one of the biggest challenges to services. It can cause serious consequences to the health and well-being of the individual and those involved in their care, including exclusion from services or social groups. There is a greater risk of violence in the ID population and aetiological causes include biological and psychosocial factors and developmental disorders such as ASD and ADHD. Key management strategies involve a review of these factors, robust risk assessments and collaborative working utilising a multidisciplinary approach. Psychological and behavioural support interventions offered should be person-centred and tailored according to their needs. The goal is to assess and modify psychological, environmental or social factors and improve challenging behaviour. Pharmacological treatment can be helpful where underlying physical or mental health illnesses contribute to aggression. In those without obvious causes of violent behaviour, psychotropic medication can be also used to attenuate risks; however, current evidence base is limited and medication options should be considered on a case-by-case basis.