Delirium is an acute disturbance in mental status characterized by fluctuations in cognition and attention that affects more than 2.6 million hospitalized older adults in the United States annually, a rate that is expected to increase with the aging population. Delirium is associated with a myriad of poor outcomes, including prolonged hospital stay and readmission, loss of independence, new or accelerated cognitive impairment, and death. The relationship between delirium and dementia is complex, as dementia is one of the most significant risk factors for delirium, and delirium is independently associated with an increased risk of subsequent cognitive decline. Here, we provide a current review on the epidemiology, evaluation and management of older adults with delirium, focusing on those instances where it can be mistaken for a dementing illness.

Galen system is based on three pillars: the affected body part, the type of qualities imbalanced, and the degree of imbalance. Therefore, he only distinguishes between mental illness and impaired consciousness when there is a difference between these two entities in any of these three pillars. Thus, he distinguishes phrenitis from melancholia but not from mania. The emphasis on the system, on the other hand, enables him a very tight notion of disease, where symptoms, mechanisms, affected organ and treatment are closely linked.

4 Post-Hellenistic authors present a more compartmentalised idea of diseases in general and of impaired consciousness in particular. Unlike the Hippocratics, who barely discussed mental illness, these authors did distinguish impaired consciousness from mental illness through a classificatory system of dichotomic oppositions, additionally they discussed new conditions which are not mentioned in the HC. In most theorisations, perceptions play an increasingly relevant role to understand these conditions.

A diachronic look at the contrast between mental illness and impaired consciousness among these ancient doctors shows a trend towards a more compartmentalised idea of these conditions, a stronger notion of disease, and a progressive abstract framing of clinical findings into theoretical classificatory models and comprehensive pathophysiological systems.

This introductory chapter presents and contextualises the main sources under study, and addresses the problems of a definition of consciousness. Given the vagueness of the notion, a working definition is proposed, which is based on cognitive model that uses three prototypical clinical presentations of impaired consciousness: delirium, sleep and fainting.

Contrary to mainstream scholarship’s opinion, the Hippocratic corpus presents many cases of impaired consciousness, but only a few of mental illness. By looking at three study cases, this chapter describes how these doctors understood conditions where patients act weirdly or were not their usual selves, and how they construed the notion of disease.

In face of the difficulty of establishing clear biological boundaries between sleep and the other forms of impaired consciousness, the sociological and anthropological analyses can provide hints as to where those limits were set in real life. The terminological analysis suggested a common feature that persisted throughout the different authors and periods: different levels of consciousness (from drowsy to hyperactive, and from delirium to koma) where always related to the impairment of mental capacities, regardless of the way in which each medical writer grouped or understood them.

Unlike mental disease, which presupposes a strongly theory-laden concept, impaired consciousness or delirium is currently conceived in medicine as a cluster of symptoms. This chapter contrasts these two constructs, and discusses our current idea about the notion of disease.

Chapter 21 covers the topic of delirium and neurocognitive disorders. Through a case vignette with topical MCQs for consolidation of learning, readers are brought through the diagnosis and treatment of a patient with delirium and neurocognitive disorder. Topics covered include diagnosis, mild and major neurocognitive disorders, types of neurocognitive disorders, risk factors for Alzheimer’s disease, instruments used in evaluation, investigations, pharmacological and non-pharmacological management of neurocognitive disorders, adverse effects of medications, delirium and its diagnosis, pharmacological and non-pharmacological management of delirium, and beahvioural and psychological symptoms of dementia.

Chapter 51 covers the topic of old age psychiatry. Through a case vignette with topical MCQs for consolidation of learning, readers are brought through the management of elderly patients with psychiatric disorders from first presentation to subsequent complications of the conditions and its treatment. Things covered include the general principles of prescribing in elderly patients with psychiatric disorders, the use of covert administration of medications, the use of medications in patients with neurocognitive disorders and variations in the presentation of depression.

In this chapter, we discuss late-life psychiatric disorders highlighting their unique biological, clinical, and therapeutic features compared to presentations earlier in life. They are frequently overlapping and associated with dementia and other neurodegenerative diseases. The three D’s – delirium, dementia, and depression – represent common geriatric psychiatry syndromes that can pose diagnostic and therapeutic challenges. Clinical suspicion of delirium must prompt careful investigation of the underlying cause. Dementia is an umbrella term that describes progressive cognitive decline and related behavioral and functional impairments. Behavioral symptoms of dementia are a frequent reason for psychiatry referral. They have a more irregular course than the cognitive decline, and can be categorized in distinct dimensions. Late-life depression has unique features, such as the focus on somatic complaints instead of mood changes.

Delirium or acute brain dysfunction is the most common psychiatric condition. In the medical hospital. It is often not recognized and minimized by staff and predisposes patients to accelerated cognitive decline, depression, and PTSD. Treatment of the underlying medical conditions is essential. Keeping the patient safe and education of family members are equally important. There are no FDA approved medications to treat delirium, but Dexmedetomidine (alpha-2 agonist) has been beneficial in controlling agitation.

Agitation is an umbrella term for a spectrum of behaviors characterized by increased motor activity, restlessness, and emotional tension. Agitation is a cause of morbidity and complications during emergency center or hospital stays. The etiology of agitation states can be medical, psychiatric, substance or medication related, or as a result of delirium, and can be exacerbated by environmental factors. The goals of agitation assessment and management are (1) to ensure the safety of the patient and other individuals present, (2) the identification of risk factors (and cause, if possible) for psychomotor agitation, and (3) the implementation of the appropriate treatment in a timely and efficient manner. Pharmacological and nonpharmacological management strategies are needed for proper management, and teams should always start with verbal de-escalation and environmental modifications, followed by least-invasive means of administration of pharmacological agents, and potentially advancing to seclusion and restraints. Special considerations should be assessed in children, elderly, pregnant women, and those with medically unstable pictures who present with agitation, keeping in mind that delirium is underdiagnosed and goals of treatment must be customized.