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Evaluation of abnormal behavior in the emergency department

J Stephen Huff, MD
Section Editor
Robert S Hockberger, MD, FACEP
Deputy Editor
Jonathan Grayzel, MD, FAAEM


Altered behavior ranges from subjective difficulty thinking clearly to abnormal thought content and states of depressed consciousness. When altered behavior directs the diagnostic workup, this implies that confusion, thought problems, or altered mental status is the chief complaint. Adjunctive complaints such as dyspnea, hypoxia, high fever, or acute focal neurologic deficits shift the clinician's approach.

Confusion is thought to be present in up to 50 percent of elderly hospitalized patients, 10 percent of all hospitalized patients, and 2 percent of emergency department patients [1].

The differentiation of abnormal behavior may be straightforward or complex. Sometimes no single explanation for altered mental status can be identified. Frequently, an acute medical illness exacerbates confusion in patients with dementia, essentially creating coexistent acute and chronic confusional states.

The focus of this review is the differentiation of acute medical and neurologic disorders from psychiatric causes of abnormal behavior in the emergency setting. The evaluation of the demented or agitated patient is discussed elsewhere. (See "Evaluation of cognitive impairment and dementia" and "Assessment and emergency management of the acutely agitated or violent adult" and "Diagnosis of delirium and confusional states".)


Altered behavior and confusion are terms without strict medical definitions. A "confused" patient frequently comes to medical attention because in the judgment of someone (family, caregiver, observers, or police) some behavior is deemed unusual for the individual or deviates from societal norms. Less commonly do patients complain of confusion, consistent with the frequent lack of insight into their altered behavior. Delirium is an acute change in attention and mental functioning, and the formal definition includes disturbance of wake-sleep cycles and fluctuating confusion. Dementia is a chronic confusional state with insidious onset. The two conditions can and frequently do coexist. (See "Evaluation of cognitive impairment and dementia" and "Diagnosis of delirium and confusional states".)


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Literature review current through: Sep 2016. | This topic last updated: May 22, 2015.
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  1. Hustey FM, Meldon SW. The prevalence and documentation of impaired mental status in elderly emergency department patients. Ann Emerg Med 2002; 39:248.
  2. Huff JS. Confusion. In: Emergency Medicine: A Comprehensive Study Guide, Tintnalli JE, Stapczynski JS, Cline DM, et al. (Eds), McGraw-Hill, New York 2011. p.1135.
  3. Huff JS. Confusion. In: Rosen's Emergency Medicine: Concepts and Clinical Practice, Marx JA, Hockberger RS, Walls RM. (Eds), Elsevier Health Sciences, Philadelphia 2010. p.101.
  4. Talbot-Stern JK, Green T, Royle TJ. Psychiatric manifestations of systemic illness. Emerg Med Clin North Am 2000; 18:199.
  5. Leopold NA, Borson AJ. An alphabetical 'WORLD'. A new version of an old test. Neurology 1997; 49:1521.
  6. Zun L, Gold I. A survey of the form of the mental status examination administered by emergency physicians. Ann Emerg Med 1986; 15:916.
  7. Folstein MF, Folstein SE, McHugh PR. "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975; 12:189.
  8. Huff JS, Farace E, Brady WJ, et al. The quick confusion scale in the ED: comparison with the mini-mental state examination. Am J Emerg Med 2001; 19:461.
  9. Irons MJ, Farace E, Brady WJ, Huff JS. Mental status screening of emergency department patients: normative study of the quick confusion scale. Acad Emerg Med 2002; 9:989.
  10. Kaufman DM, Zun L. A quantifiable, Brief Mental Status Examination for emergency patients. J Emerg Med 1995; 13:449.
  11. Wilber ST, Lofgren SD, Mager TG, et al. An evaluation of two screening tools for cognitive impairment in older emergency department patients. Acad Emerg Med 2005; 12:612.
  12. Carpenter CR, Bassett ER, Fischer GM, et al. Four sensitive screening tools to detect cognitive dysfunction in geriatric emergency department patients: brief Alzheimer's Screen, Short Blessed Test, Ottawa 3DY, and the caregiver-completed AD8. Acad Emerg Med 2011; 18:374.
  13. American College of Emergency Physicians. Clinical policy for the initial approach to patients presenting with altered mental status. Ann Emerg Med 1999; 33:251.
  14. Inouye SK. Delirium in older persons. N Engl J Med 2006; 354:1157.