Published 28 November 2014
Cite this as: BMJ 2014;349:g7265
06 December 2014, Valerie J Page, Consultant in Critical Care, Watford General Hospital, Watford, UK
Re: Delirium on the intensive care unit - authors response
Thank you for your responses, both are extremely pertinent with regard to the mysteries of delirium. Dr Jordan makes the valid point that the evidence to date linking delirium and long-term cognitive outcomes falls short of proving causality. I would maintain, however linking acute and chronic brain failure makes sense physiologically and is supported by what is known to date from animal and clinical studies. [1,2] As Dr Man confirmed, in the BRAIN-ICU the cognitive deficits were present across all age groups and pre-existing cognitive impairment was accounted for as far as possible.  Also, with regard Dr Man’s point regarding risk factors a small postmortem study has shown an upregulation of CNS inflammation in patients who died with delirium, which was unrelated to infection .
There are many unanswered questions with regard to delirium from the pathophysiology, diagnosing delirium to the key question of whether patient’s outcomes can be improved. Now what is of the essence is that there is recognition of the importance of delirium, together with a willingness and engagement of scientific and clinical communities to work on the answers.
1. Field RH, Gossen A, Cunningham C. Prior pathology in the basal forebrain cholinergic system predisposes to inflammation induced working memory deficits: reconciling inflammatory and cholinergic hypotheses of delirium. J Neurosci 2012; 32: 6288-94
2. Popp J. Delirium and cognitive decline: more than a coincidence. Curr Opin Neurol 2013; 26: 634-9
3. Pandharipande PP, Girard TD, Jackson JC, Morandi A, Thompson JKL, Pun BT, et al, Long-term cognitive impairment after critical illness. N Engl J Med2013;369:1306-16.
4. Munster BC, Aronica E, Zwinderman AH, Eikelenboom P, Cunningham C, Rooij SE. Neuroinflammation in delirium: A postmortem case-control study. Rejuvenation Res. 2011;14:615–622
Competing interests: No competing interests
(bolding is mine)