Delirium and long-term cognitive impairment.
Delirium is a severe, acute neuropsychiatric syndrome that is highly prevalent in acute hospital populations. Delirium has noticeable effects on length of hospitalization, cost of care, mortality and morbidity. In addition to these well-established adverse consequences, there is increasing evidence linking delirium and a higher risk of long-term cognitive impairment (LTCI), including dementia. A prior review (Jackson, Gordon, Hart, Hopkins, & Ely, 2004), in which nine studies (total N = 1,885, years 1989-2003) were considered, concluded that there was evidence for an association between delirium and LTCI. Here we provide a review of studies published since Jackson's review. We included nine reports, with a total of 2,025 patients. The studies show diverse sample sizes, methodologies, designs and patient populations. However, taken together, the results of these new studies broadly confirm that there is a link between delirium and LTCI. We go on to discuss putative mechanisms and explanations. These include (1) delirium as a marker of chronic progressive pathology, but unrelated to any progression, (2) delirium as a consequence of acute brain damage which is also responsible for a 'single hit' or triggering of active processes causing LTCI, (3) delirium itself as a cause of LTCI, and (4) drug treatment of delirium or other conditions as a cause of LTCI. We conclude with suggestions for future research.
MacLullich
Alasdair M J
AM
Department of Geriatric Medicine, University of Edinburgh, Royal Infirmary of Edinburgh, Edinburgh, Scotland, UK. a.maclullich@ed.ac.uk
Beaglehole
Anna
A
Hall
Roanna J
RJ
Meagher
David J
DJ
D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology*; D003693:Delirium / Q000453:epidemiology* / Q000523:psychology*; D006801:Humans; D009483:Neuropsychological Tests; D013997:Time Factors