Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android


Altered mental status and coma are broad clinical categories used to describe disorders of arousal and content of consciousness. Arousal behaviors include wakefulness and basic alerting. Content of consciousness includes awareness, memory, language, reasoning, spatial relationship integration, emotions, complex attention, and the myriad integration processes that make us human. Delirium, dementia, and coma may each affect consciousness, but their clinical presentations are distinct. Prompt and accurate differentiation between the three conditions is essential for appropriate management in the ED setting. Coma is characterized by failure of both arousal and content functions of consciousness. The altered states of delirium and dementia have multiple effects on neuropsychological function to varying degrees. While delirium refers to an acute state of fluctuating attention and change in cognition, dementia is a chronic disorder of deteriorating cognition, with or without behavioral disturbances. Psychiatric disorders and altered mental states may share features such as hallucinations or delusions. Some distinctions between the different states are summarized in Table 168-1.

TABLE 168-1Features of Delirium, Dementia, and Psychiatric Disorder



Delirium, acute encephalopathy, and other synonyms all refer to an abrupt disorder characterized by impairment of attention and cognition. While delirium may present at any age, it is much more prevalent in older adults. The literature suggests that at least 1 out of 10 elderly ED patients and at least 1 out of 4 elderly hospitalized patients have delirium at the time of admission.1-4 Emergency physicians may fail to recognize delirium in three out of four of such cases.3,4 Given evidence that delirium in ED patients is associated with an increase in morbidity, mortality, and hospital length of stay, the Society for Academic Emergency Medicine Geriatric Task Force has recommended that formal cognitive assessment should be a quality indicator in emergency care of the elderly.3,5-7


The pathologic mechanisms leading to delirium are complex and are thought to involve impairments in neuronal connectivity and plasticity, leading to “acute brain failure.”3,8 There are five general causes9:

  1. Primary intracranial disease

  2. Systemic diseases secondarily affecting the CNS

  3. Exogenous toxins (including prescribed pharmacotherapies)

  4. Drug withdrawal and pain

  5. Major trauma or surgery


Delirium typically develops over days. Disordered attention and ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.