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This chapter discusses the diagnosis and differentiation of delirium and dementia in the elderly and provides an overview of selected common mental health disorders in the aging population.

The proportion of ED visits by older adults continues to increase with the exponential growth of the geriatric population.1 Delirium, dementia, and depression can affect older adults, and the disorders are often interrelated. It can be difficult to identify delirium in patients with dementia, particularly because individuals with dementia are more likely to develop delirium.2 Patients who develop delirium are more likely to develop dementia later in life.3,4,5,6 Distinguishing between dementia and delirium is an important aspect of caring for older patients.

It can also be difficult to diagnose depression in patients with dementia given that both can present with similar symptoms such as apathy.7 Also, depression in late life has been associated with increased risk of developing dementia, further demonstrating that dementia, delirium, and depression are interconnected, increase the risk of each other, and are all associated with increased risk of mortality and morbidity.8,9,10,11,12,13,14 Table 288-1 provides distinguishing features of delirium, dementia, and psychiatric disorders. Chapters 168, "Altered Mental Status and Coma," and 286, "Mental Health Disorders: ED Evaluation and Disposition," also discuss the distinctions between delirium, dementia, and psychiatric disorders.

TABLE 288-1Features of Delirium, Dementia, and Psychiatric Disorder


Delirium is an acute change in cognition that fluctuates rapidly over time and is often reversible.15 Delirium is frequently the first sign of underlying acute medical illness. Patients demonstrate altered levels of consciousness, inattention, disorganized thinking, and altered perception.15 There are three main types of delirium: hypoactive, hyperactive, and mixed.16 By far, the most common types are hypoactive and mixed delirium, which also have the highest potential to be missed.17,18,19,20,21,22,23 Hypoactive delirium has been called "quiet delirium" because patients have decreased psychomotor activity and can appear somnolent. If hypoactive delirium is confused for depression, the underlying medical disorder causing the delirium can be missed.24,25,26 Hyperactive delirium, in contrast, is characterized by increased psychomotor activity, and patients are often agitated, anxious, and sometimes combative. ...

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