Can blood markers and genes diagnose Alzheimer’s?
In 1,439 AD cases and 508 older controls, combining plasma Aβ40/42, P-tau181, NfL, GFAP with APOE and PRS reached AUC 0.81; case-only GWAS linked Aβ42/Aβ40 to WWOX and COPG2.
Source
Plasma biomarkers and genetics in the diagnosis and prediction of Alzheimer's disease
Study at a glance
- Design
- Case-control — AD Cardiff Cohort cases vs screened elderly controls; Simoa plasma biomarkers plus GWAS/PRS; clinical diagnosis not CSF/PET-confirmed.
- N
- N=1947 · 1,439 AD cases (mean age 68) and 508 controls (mean age 82); 1,947 with APOE and genome-wide genotypes.
- Population
- Early- and late-onset sporadic Alzheimer’s disease cases and screened elderly controls from the Alzheimer’s Disease Cardiff Cohort.
- Outcome
- Discrimination of clinical AD (AUC) by plasma Aβ40/42, P-tau181, NfL, GFAP plus APOE/PRS, and GWAS of biomarkers.
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
Measured five Simoa plasma biomarkers in the AD Cardiff Cohort, related them to age at onset/duration, built prediction models with APOE-ε4 and polygenic risk, and ran case-control and case-only GWAS.
What they found
Aβ-related peptides were lower in cases; P-tau181, NfL, and GFAP were higher. All markers associated with age. Combined biomarkers + APOE + PRS AUC=0.81 (drivers: ε4, Aβ40/42, GFAP, NfL). ε4 associated with all markers except NfL. P-tau181 variance was largely captured by ε4. Case-only GWAS found WWOX and COPG2 for the Aβ42/Aβ40 ratio.
The limits
What it doesn't show
AD diagnosis was clinical, not CSF/PET/autopsy-confirmed (~25% clinical AD lack pathology at autopsy, as the authors note); controls were older than cases; novel GWAS hits need replication and are not a screening program.
Key terms
- Simoa
- Single molecule array ultrasensitive immunoassay used for plasma biomarkers.
- P-tau181
- Tau phosphorylated at threonine 181, a relatively AD-specific plasma marker.
- GFAP
- Glial fibrillary acidic protein; plasma marker of astrocytic activation.
- NfL
- Neurofilament light chain; axonal-injury marker with low disease specificity.
- APOE-ε4
- Major AD risk allele associated here with all biomarkers except NfL.
- Aβ42/Aβ40 ratio
- Plasma amyloid-β fragment ratio linked to brain amyloid and, here, to WWOX/COPG2.
Flashcards
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Cases vs controls were about:
Common questions
How many people?
1,439 cases and 508 controls (1,947 genotyped).
Combined diagnostic AUC?
0.81 using all biomarkers plus APOE and PRS.
Which GWAS genes for Aβ ratio?
WWOX and COPG2 in a case-only analysis.
Did ε4 associate with NfL?
No; ε4 associated with the other biomarkers.
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