Table 2. Ionized calcium-binding adapter molecule 1 (Iba1).
| First author | Brain bank | N | Sex | Age | AD genetic risk factors | AD histologically confirmed and criteria | Braak stage | C history of neurological or psychiatric disease | PMI (h) | Brain region | Technique | Marker | Direction of results |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Bachstetter69 | University of Kentucky Alzheimer’s Disease Center | AD: 7 C: 9 | AD: 4/3 C: 6/3 | AD: 77 C: 86 | APOE: AD: NA: 2, 4/4: 1, 3/4: 2, C: 3/4: 1 | CERAD | AD: ~VI C: ~II | NR | AD: 4.2 C: 2.4 | Hippocampus: CA1, CA2/3, CA4, DG, subiculum and adjacent white matter Morphology assessed in the CA1 only | IHC | Iba1 | ↔Iba1 staining or cell counts in any hippocampal area ↔ in CA1 Iba1+ microglial morphology |
| Griciuc70 | Massachusetts ADRC | AD: 25 C: 15 | AD: 7/18 C: 6/9 | AD: 79.2 C: 79.9 | APOE carrier: AD: 18 (8 homozygous) C: 5 (0 homozygous) | NIA-Reagan Institute Criteria | NR | NR | AD: 17 C: 29 | Frontal cortex | IHC (stereology), western | Iba1 | ↔ Iba1+ microglia (data not shown) ↔ Iba1 protein (nonsignificant increase) |
| Magistri71 | BSHRI | AD: 4 C: 4 | AD: 1/4 C: 2/2 | AD: 83.75 (not exact, one age just listed >90) C: 83.5 | AD: all APOE3/3 C: APOE2/3: 2 APOE3/3: 1 NR: 1 | NIA-Reagan criteria | AD: V: 1 VI: 3 C: I: 1 II: 3 | NR | AD: 2.5 C: 2.5 | Hippocampus | RNA seq (gene expression) | Iba1 | ↔ |
| Nielsen62 | NBB | AD: 4 C: 5 | AD: 1/3 C: 1/4 | AD: 76.3 C: 77.6 | NR | Yes | AD: III: 1, IV: 2, V: 1 C: 0: 1, I: 3 II: 1, | NR | AD: 6.3 C: 6.1 | Entorhinal cortex, hippocampus | IHC | Iba1 | ↑ |
| Dal Bianco20 | NR | AD: 9 C: 15 | AD: 0/9 C: 13/2 | AD: 81 C: 70 | NR | Braak, CERAD | AD: IV: 2, V: 4, VI: 3 | No neurological disease or brain lesions | NR | Cortical areas of the temporal lobe, including entorhinal cortex, hippocampus and temporal cortex | Immunocytochemistry | AIF-1 | ↑ AIF-1 near plaque only |
| Davies72 | New South Wales Brain Bank | AD: 7 C: 5 | AD: 3/4 C: 2/3 | AD: 83.6 C: 83.0 | NR | Braak, CERAD, National Institute on Aging-Alzheimer's Association Guidelines for Neuropathological Assessment of AD | AD: V: 3 VI: 4 C: 0: 4 I: 1 | No co-existing pathology | AD: 12.3 C: 15.4 | Cingulate cortex, inferior temporal cortex | IHC | Iba1 | ↔ Cell density ↑ Microglia with dystrophic morphology, activated morphology (lower ramification) |
| Satoh68 | NR | : AD: 7 C: 14 | AD: 5/5 C: 6/5 | AD: 70 C: 75 | NR | Braak, CERAD | AD: VI: 10 | 4 Died of nonneurological causes, 3 with Parkinson’s, 4 ALS | NR | Frontal cortex | IHC, qPCR | Iba1 | PCR: ↑ IHC: ↔ |
| Tang65 | University of Kentucky Alzheimer's Disease Center Autopsy Program | AD: 10 C: 10 | AD: 5/5 C: 6/4 | AD: 82.1 C: 82.7 | NR | NIA-Reagan criteria | AD: VI: 6 C: I–III, (avg 1.6) | No neuropathology | AD: 26.2 C: 6.2 | Inferior parietal cortex | Western | Iba1 | ↑ |
| Ekonomou73 | United Kingdom MRC Cognitive Function and Ageing Study | AD: 13 C: 15 | 14/28 (both AD and C) | Whole sample: 84.8 | NR | Braak | Whole sample: 0–II: 12, III–IV: 11, V–VI: 5 | No neurological disease | All within 17.5–25.0 | Hippocampus DG | IHC | Iba1 | ↔ Between AD and C ↑ in Braak stage 3–4 than 0–2 or 5–6 |
| Korvatska32 | University of Washington Neuropathology Core Brain Bank | AD (normal TREM2): 6 AD (with TREM2 R47H variant): 7 C: 3 | NR | Whole sample: 84.9 | NR | CERAD | AD: III: 1, V: 4, VI: 1 AD R47H: V: 6, VI: 1 C: 0: 1, I: 1, III: 1 | NR, one C CERAD score A and one B | All avg 4.5 | Frontal lobe: grey and white matter Hippocampus: CA1, hilus, parahippocampal gyrus and white matter | IHC | Iba1 | ↓ Staining in hippocampus and frontal lobe white matter ↔ Staining in hilus, CA1, parahippocampal gyrus or frontal lobe grey matter ↔ Counts in frontal lobe grey matter or activated counts in hippocampus white matter in AD, though ↓ in R47H |
| Lastres-Becker67 | Banco de Tejidos de la Fundacion CIEN | AD: 4 C: 4 | NR | AD: 73–90 C: 78–90 | NR | Braak | AD: II–IV | No neuropsychiatric disease or neuropathology | All within 5 h | Hippocampus | IHC, immunoblot | Iba1 | ↑ |
| Lee74 | OPTIMA and Newcastle Brain Tissue Resource (NBTR) | AD: 12 C: 11 | AD: 7/5 C: 6/5 | AD: 73.1 C: 81.1 | NR | Braak, CERAD | AD: V–VI C: I–II | NR | AD: 61.2 C: 41.5 | Prefrontal (BA9) and temporal (BA22) cortices | PCR | Iba1 | ↔ |
| Lue61 | BSHRI | AD: 11 C: 11 HPC: 11 | AD: 6/5 C: 7/4 HPC: 3/8 | AD: 82.4 C: 85.4 HPC: 86.5 | APOE 4 Carriers: AD: 5/6 C: 1/10 HPC: 2/9 | Braak, CERAD | AD: Avg 5.2 C: Avg 2.8 HPC: Avg 2.9 | NR | NR | Middle temporal cortices | Western | Iba1 | ↑ Than C and HPC |
| Marlatt75 | Netherlands Brain Bank | AD: 8 C: 8 | AD:4/4 C: 4/4 | AD: 81 C: 80 | NR | Braak | AD: Avg 4.8 C: Avg 1.4 | NR | All within 5–7 | Hippocampus (CA1/2, CA3, DG/SCZ, Hilus) | IHC | Iba1 | ↔ In cell number or in morphology |
| Minett56 | Medical Research Council Cognitive Function and Ageing Study—six centres in UK | AD: 83 C: 130 | AD: 64/53 C: 51/66 | AD: 89 C: 84 | NR | CERAD | NR | NR | NR | Middle frontal gyrus (BA9) | IHC | Iba1 | ↓ Iba1 no association with cognition (MMSE), positive association with AD pathology (plaques, tangles) |
| Rangaraju63 | Emory ADRC Neuropathology Core, Atlanta | AD: 10 C: 10 | AD: 6/4 C: 6/4 | AD:71.5 C: 71.5 | APOE: AD: 8 with APOE4 (3 homozygous) C: 1 APOE4 (0 homozygous | Yes | AD: All VI C: 0 | NR | NR | Frontal cortex | IHC | Iba1 | ↑ Iba1 staining density, P=0.06 for staining intensity |
| Rivera64 | KPBBB, University Medical Center | Braak stage 0–1: 12, 2–3: 12 4–5: 12 6: 9 | Braak stage: 0–1: 6/6 2–3: 5/7 4–5: 3/9 6: 0/9 | Braak stage: 0–1: 74.4 2–3: 81.1 4–5: 82.1 6: 71.8 | APOE4/4: Braak stage 0–1: 1 2–3: 4 4–5: 5 6: 0 | Braak, NIA-Reagan Criteria | AD: II–VI C: 0–I | NR | All <16 h | Anterior frontal cortex | PCR | AIF1 IBA1 | ↑ |
| Sanchez-Mejias76 | Tissue bank at Fundación CIEN | Braak stage 0: 8 II: 13, III–IV: 9, V–VI: 17 | Braak stage 0: 5/3, II: 7/13, III–IV: 4/5, V–VI: 7/11 | Braak stage 0: 19, II: 78, III–IV: 80, V–VI: 79 | NR | Braak Braak V–VI clinically classified as AD, Braak II age-matched and used as C | Braak stage 0: 8, II: 13, III–IV: 9, V–VI: 17 | NR | Braak stage 0: 8 II: 7, III–IV: 6, V–VI: 8 | Hippocampus CA1, CA3, parahippocampal gyrus | IHC, PCR | Iba1 | PCR: ↔ Iba1 IHC: ↓ in DG and CA3 ↔CA1 and parahippocampal gyrus More activated morphology |
| Serrano-Pozo54 | Massachusetts ADRC Brain Bank | AD: 40 C: 32 | AD: 14/26 C: 13/19 | AD: 81.3 C: 77.6 | APOE4: AD: 21/40 C: 5/27 | NIA-Reagan criteria | NR | No clinical history of neurological disorders and did not meet the pathological criteria for any neurodegenerative disease | AD: 18.0 C: 14.1 | Temporal polar association cortex (BA 38) | IHC, stereology | Iba1 | ↔ Total microglia ↓IBA1+/MHC2- microglia ↑IBA1-/MHC2+ microglia ↔IBA1+/MHC2+ microglia ↑ IBA1+/MHC2+ microglia in APOE4+ ↔with microglia by genotype |
| Walker60 | BSHRI | AD: 30 C: 41 | Whole sample: AD: 49/48 C: 50/46 | Whole sample: AD: 82.2 C: 84.9 | APOE4/4 genotypes excluded | NIA-Reagan criteria | NR | NR | Whole sample: AD: 3.6 C: 4 | Temporal cortex | Western | Iba1 | ↑ For CD33 rs3865444 allele A/C genotype ↔ For C/C and A/A genotypes |
Abbreviations: AD, Alzheimer’s disease; ADRC, Alzheimer’s Disease Research Center; ALS, amyotrophic lateral sclerosis; APOE, apolipoprotein E; Avg, average; BSHRI, Banner Sun Health Research Institute; BA, Brodmann area; C, Control; CA, Cornu ammonis; CD, cluster of differentiation; CERAD, Consortium to Establish a Registry for Alzheimer’s Disease; CIEN, Centro Investigación Enfermedades Neurológicas; DG, dentate gyrus; HPC, high pathology control; Iba1, ionized calcium-binding adapter molecule 1; IHC, immunohistochemistry; KPBBB, Kathleen Price Bryan Brain Bank; MRC, Medical Research Council; MMSE, mini-mental state examination; NA, not available; NBTR, Newcastle Brain Tissue Resource; NBB, Netherlands Brain Bank; NIA, National Institute on Aging; NR, not reported; OPTIMA, Oxford Project to Investigate Memory and Aging; PMI, post-mortem interval; Seq, sequencing; TREM2, triggering receptor expressed on myeloid cells 2.
Results are expressed relative to control unless specified otherwise. Where there are both young and older controls, values are reported for the older (age-matched controls).