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Diagnosis of delirium and confusional states

INTRODUCTION

Delirium and confusional states are among the most common mental disorders encountered in patients with medical illness, particularly among those who are older. They are associated with many complex underlying medical conditions and can be hard to recognize. Systematic studies and clinical trials are difficult to perform in patients with cognitive impairment. Recommendations for evaluating and treating delirium are based primarily upon clinical observation and expert opinion [1].

Knowledge of the clinical epidemiology of delirium and confusional states in various settings has substantially increased as a result of applying standardized diagnostic methods. These prospective observational studies provide a basis for understanding and managing the disorder.

The epidemiology, pathogenesis, clinical features, and diagnosis of delirium and confusional states will be reviewed here. The prevention and treatment of these disorders are discussed separately. (See "Prevention and treatment of delirium and confusional states".)

DEFINITION AND TERMINOLOGY

The American Psychiatric Association's Diagnostic and Statistical Manual, 4th edition (DSM-IV) lists four key features that characterize delirium [2]:

  • Disturbance of consciousness with reduced ability to focus, sustain, or shift attention.
  • A change in cognition or the development of a perceptual disturbance that is not better accounted for by a preexisting, established, or evolving dementia.
  • The disturbance develops over a short period of time (usually hours to days) and tends to fluctuate during the course of the day.
  • There is evidence from the history, physical examination, or laboratory findings that the disturbance is caused by a medical condition, substance intoxication, or medication side effect.
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