Table 2.
Overview of potential plasma biomarkers shared between delirium and dementia
| Biomarker | Cohort size | Findings | Ref. | |||
|---|---|---|---|---|---|---|
| No delirium, no dementia | Dementia only | Delirium only | DSD | |||
| Systemic inflammation | ||||||
| CRP | 421 (80 with APOE ε4; 341 without APOE ε4) | 0 | 132 (26 with APOE ε4; 106 without APOE ε4) | 0 | In presence of APOE ε4, higher CRP was associated with delirium | 68 |
| IL-6 | 69 | 23 | 16 | 48 | Higher IL-6 was associated with longer ED delirium duration, but only in participants without dementia | 66 |
| IL-6, IL-8 | 48 | 10 | 22 | 40 | Higher S100B associated with delirium; S100B correlated with IL-6 and IL-8 | 101 |
| AD biomarkers | ||||||
| Aβ1–40, Aβ1–42, t-tau, p-tau181 | 72 | Excluded | 38 | 0 | Higher plasma tau was associated with delirium incidence and severity | 89 |
| t-tau, p-tau217, p-tau181 | 22 | Not specified | 16 | NA | t-tau, p-tau217 and p-tau181 were elevated after major cardiac surgery; only t-tau was associated with the incidence and severity of postoperative delirium; models adjusted for baseline cognition (MoCA) | 166 |
| Genetic factors | ||||||
| APOE ε4 | 6 (APOE ε4 not reported) | 7 (includes both dementia only and DSD; 2 with APOE ε4) | 47 (APOE ε4 not reported) | Not reported | Presence of at least one APOE ε4 allele was associated with longer delirium duration | 93 |
| 117 (no delirium but might have had dementia) | 82 (includes both dementia only and DSD) | 45 | Not reported | APOE genotyping was performed in 116 participants. At least one APOE ε4 allele was present in 26 participants, with no difference in frequency between delirium and no delirium groups; lower IGF1 and absence of the APOE ε4 allele predicted recovery from delirium; APOE ε4 alone did not show an effect on recovery | 70 | |
| 161 (33 with APOE ε4) | 0 (60 with ‘history of CNS disorder’) | 29 (13 with APOE ε4) | Not reported | Presence of at least one APOE ε4 allele was associated with an increased risk of early postoperative delirium | 94 | |
| Neuronal injury | ||||||
| NfL | 114 | 38 | 46 | 116 | Higher NfL concentration was associated with delirium | 103 |
| S100B | 0 | 20 | 20 | 0 | No association between serum S100B concentration and delirium | 102 |
| 48 | 10 | 22 | 40 | Higher S100B concentration was associated with delirium | 101 | |
| Other | ||||||
| PAI1 | 69 | 23 | 16 | 48 | Higher PAI1 was associated with longer ED delirium duration, but only in participants without dementia | 66 |
| IGF1 | 117 (no delirium but may have had dementia) | 82 (includes both dementia only and DSD) | 45 | Not reported | Delirium associated with lower IGF1 | 70 |
| Diazepam-binding inhibitor | 15 | 30 | 30 | 0 | Higher levels in individuals with dementia than in control individuals; higher levels in individuals with delirium than in individuals with dementia | 111 |
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. Aβ, amyloid-β; AD, Alzheimer disease; DSD, delirium superimposed on dementia; ED, emergency department; IGF-1, insulin-like growth factor-1; MoCA, Montreal Cognitive Assessment; NA, not available; NfL, neurofilament light; PAI-1, plasminogen activator inhibitor-1; p-tau, phosphorylated tau; t-tau, total tau.