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Delirium as a disorder of consciousness
  1. Ravi Bhat1,
  2. Kenneth Rockwood2
  1. 1
    Goulburn Valley Area Mental Health Service, University of Melbourne, Shepparton, Victoria, Australia
  2. 2
    Division of Geriatric Medicine, Dalhousie University, Halifax, NS, Canada
  1. Professor Kenneth Rockwood, Centre for Health Care of the Elderly, 1421–5955 Veterans Memorial Lane, Halifax, Canada B3H 2E1; Kenneth.Rockwood{at}

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Delirium is a common clinical phenomenon, often described as a disorder of consciousness. Delirium is commonly under recognised. The usual response to under recognition is to exhort practitioners to do a better job, but perhaps under recognition should instead be seen as a daily pragmatic challenge to how delirium is conceptualised. Here we retain the view that delirium is a disorder of consciousness, but propose a more multidimensional approach to this key feature. We argue that delirium can be recognised through evaluating arousal, attention and temporal orientation. We suggest that this approach can be validated by testing whether it leads to better delirium identification, accounts for the characteristic clinical disturbances, explains why delirium is common in the extreme age groups and why in later life its boundaries often blend with dementia.

A troop of newly graduated recruits parades on final review. The march past is a portrait of symmetry, save for one young soldier, whose mother nevertheless beams from the stands: “Look! They’re all out of step but my boy John”. Such misplaced parental pride finds a modern day counterpart in the routine exhortation by delirium specialists—including ourselves—for other physicians to get in step with the expert when assessing the mental state of their patients. While physician education is important, part of the pervasive under recognition of delirium must reflect the teaching—that is, how delirium is described and discussed. Here we review some current thinking about what constitutes delirium, propose an alternate operational approach and consider some implications of this synthesis.


Can it still make sense to ask “what is delirium”? The fourth edition of the Diagnostic and Statistical Manual (DSM-IV) of the American Psychiatric Association1 defines delirium as a disturbance of consciousness and a change in cognition that develops acutely (table 1).

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Table 1 Diagnostic and Statistical Manual (DSM-IV) criteria for delirium1

Support for delirium as a …

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  • Competing interests: None.