evidence
Read in a recent review article that not much evidence on delirium pathophysiology had emerged recently. Most of the writing on this out there is just rehashing of old work. There is almost nothing on new evidence.
How can this be rectified?
Several elements have to work well for a successful project:
1. good idea: it can't be stressed enough that a well-chosen idea which attacks a particular problem in delirium research will have enormous value and attract enormous attention, whereas mediocre ideas backed up by crap methods and small studies are likely to just sit there.
I also think that a striking and, above all, clear concept has immense potency.
Stress, inattention, and delirium
Two striking features of any detailed review of the delirium literature, and indeed derived from clinical experience, is that delirium is a disorder which very often results from stress and which always results in inattention. Delirium is frequently described as being heterogeneous, a disorder of multiple, fleeting and hard to measure features. However, as Lishman pointed out and as the work of Trzepacz and Inouye has confirmed, the type of psychopathology occurring acutely in older people, often cognitively impaired who are subjected to diverse stressors or who take certain classes of drugs, is stereotyped. Acute change in mental status in these clinically extremely common contexts almost always takes the form of inattention, and a fluctuating course, and very frequently disorganised thinking and altered arousal.
These stereotyped changes can suggest approaches towards understanding the pathophysiology of delirium. How do diverse stressors lead to inattention? Why do certain classes of drugs also characteristically lead to this particular cognitive deficit?
On this basis the first place to look would be the stress-responsive areas of the brain, and of course the areas of the brain responsible for maintaining and focussing attention. In this article these will be reviewed.
Then a hypothetical model for delirium incorporating these elements will be proposed as one of perhaps several mechanisms for delirium, and areas of possible research discussed.
I should propose the stress model of delirium, or something else like that, which proposes that delirium is a disorder of the stress-responsive areas of the brain. Connect delirium with stress epidemiologically, then connect stress with cognitive change which resembles delirium. May need to analyse the concept of delirium a bit more closely (say that IRT might be required to determine which parts of the kinds of cognitive and behavioural change common in acutely unwell patients are prognostically important).
Pose questions: what features of delirium are always affected? Trzepacz and others have shown clearly that if cognitive function is dipping acutely, then attention is always affected. Not memory, but attention. More broadly
Examine the attentional parts of the brain, etc.
Say:
Neuropsychological research dating back decades has suggested that damage to certain regions and circuits of the brain result in attentional deficits
Examples:
Pharmacological research:
Amphetamine
Cocaine
What they are
2. clear hypothesis
clear plan
good methods
good statistics/power: results MUST BE DEFINITIVE
good people
good facilities
