Table 4.

Overview of potential biomarkers shared between delirium and dementia: neuroimaging and neurophysiological studies

Biomarker	Cohort size				Findings	Ref.
	No delirium, no dementia	Dementia only	Delirium only	DSD
Neuroimaging
2-[18F]Fluoro-2-deoxyglucose PET	0	4	13	4	Global cortical hypometabolism was observed during delirium (n = 13); post-delirium (n = 6) greater glucose metabolism was observed in the whole brain and bilateral PCC compared with during delirium	129
[18F]Flutemetamol PET	11	0	5	0	Participants with delirium had no evidence of amyloidosis, whereas 6 of 11 control participants did have evidence of amyloidosis	133
Structural MRI	11	0	5	0	Compared with controls, participants with delirium had reduced grey matter volumes and white matter integrity in the right temporal and bilateral medial frontal areas	124
	113	0	32	0	Patients who had thinner cortex in ‘AD signature’ regions had greater delirium severity
Resting-state functional MRI	22	0	22 (14 scanned again after resolution of delirium)	0	Increased functional connectivity between the PCC and DLPFC and reversible reduction of functional connectivity of subcortical regions was observed in delirium	122
Other imaging
Cerebral hypoperfusion (transcranial doppler)	14	10	12	8	Flow velocity was lower in participants with DSD than in participants with acute illness without delirium or dementia; flow velocity was lower in participants with DSD than in participants with either AD or delirium alone	120

Note that studies differ in methods and reporting standards, definitions and measures for delirium and dementia used, varying study populations, and presence of different comorbidities. Therefore, we report only positive or negative associations and not effect sizes, which were not directly comparable across studies. AD, Alzheimer disease; DLPFC, dorsolateral prefrontal cortex; DSD, delirium superimposed on dementia; PCC, posterior cingulate cortex.