• S T O'Keeffe and J G Devlin.
• Department of Geriatric Medicine, Beaumont Hospital, Dublin, Ireland.
• Neuropsychobiology. 1994 Jan 1;30(4):153-6.

AbstractIt has been suggested that delirium in the elderly is caused by abnormally high levels of circulating glucocorticoids or by an increased vulnerability to their effects. We performed a dexamethasone suppression test (DST) in 16 consecutive patients without depression or dementia admitted to an acute-care geriatric unit with a clinical diagnosis of lower respiratory tract infection. Seven of 9 (78%) patients who developed delirium were non-suppressors on the DST compared with 1 of 7 (14%) patients without delirium (p = 0.04). Clinical and laboratory indicators of the severity of illness did not differ between the two groups. Of the 8 patients with an abnormal DST, 1 died and another was not available for repeat assessment. On re-examination 8 weeks later, after resolution of the delirium and of the chest infection, 5 of 6 non-suppressors still had an abnormal DST. It is known that some non-demented and non-depressed elderly patients fail to suppress cortisol in response to 1 mg of dexamethasone. Our results suggest that such patients may be at increased risk for developing delirium during acute illness.

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