This experiment investigates whether traumatic brain injury (TBI) is a causal risk factor for later AD development and the mechanisms involved. Epidemiology shows associations between moderate-severe TBI and increased AD risk, but causality and mechanisms remain unclear.
AD Gap #18: What is the relationship between TBI and later AD?
Does TBI cause or accelerate AD pathology through specific mechanisms, and can post-TBI interventions reduce AD risk?
Moderate-severe TBI triggers chronic pathophysiological changes that accelerate Aβ accumulation, tau phosphorylation, and neuroinflammation. The "one-hit" hypothesis suggests that TBI causes lasting blood-brain barrier damage and microglial priming that lowers the threshold for later AD pathogenesis.
- Animal: Controlled cortical impact (CCI) model in APP/PS1 mice vs WT mice
- Cellular: Neuronal and microglial cultures from TBI-conditioned media exposure
- Human: Retrospective cohort of TBI patients with longitudinal biomarkers
Phase 1: Acute-Chronic TBI sequelae
- CCI injury in APP/PS1 mice vs WT littermates
- Longitudinal Aβ PET at 1, 3, 6, 12 months post-injury
- CSF biomarkers: Aβ42, t-tau, p-tau181, NfL at each timepoint
- Post-mortem: Aβ plaques, NFT, synaptic markers at 12 months
Phase 2: Mechanistic Pathways
- Blood-brain barrier integrity: Evans blue leakage, IgG extravasation
- Microglial priming: RNA-seq of hippocampus at acute (1 week) and chronic (6 mo) phases
- Chronic inflammation: TSPO PET at multiple timepoints
- Neuronal stress: ER stress markers, mitochondrial dysfunction
Phase 3: Human Validation
- Retrospective cohort: TBI patients with stored plasma (n=500) vs age-matched controls
- Plasma biomarkers: p-tau217, NfL, GFAP at 1, 5, 10+ years post-TBI
- Brain imaging (subset): Amyloid PET, MRI for cortical thickness
- Genetic stratification: APOE4 carriers vs non-carriers
Phase 4: Intervention Testing
- Post-TBI anti-inflammatory treatment (minocycline, colchicine) in mice
- Anti-Aβ antibody administration at 1 month post-CCI
- Metabolic support (ketogenic diet, Rolipram) for BBB repair
- Quantify TBI-accelerated pathology: Expected 2-3x acceleration of Aβ and tau in APP/PS1 mice
- Identify causal pathways: Microglial priming and BBB damage as key drivers
- Human risk estimate: APOE4 carriers at highest risk (~3-4x increase)
| Factor |
Rating |
Notes |
| Technical feasibility |
8/10 |
CCI model well-established; requires longitudinal imaging |
| Cost efficiency |
5/10 |
Long follow-up increases cost significantly |
| Timeline |
24 months |
Mouse study (12 mo) + human validation (12 mo) |
| Cross-Disease value |
6/10 |
Relevance to CTE, post-stroke dementia |
| Component |
Cost (USD) |
| Personnel (2 FTE × 24 mo) |
$320,000 |
| Mouse work (150 mice) |
$60,000 |
| PET imaging (mouse + human) |
$180,000 |
| Human cohort (500 samples) |
$100,000 |
| Biomarker assays |
$80,000 |
| Total |
$740,000 |
- Johnson et al., TBI and neurodegenerative disease (2024)
- Mouzon et al., Chronic consequences of TBI (2023)
- Raml-Cahuen et al., TBI biomarkers (2024)
Total Score: 58 (Rank 82)
| Dimension |
Score |
| Mechanistic Impact |
6 |
| Cure Proximity |
5 |
| Feasibility |
6 |
| Cost Efficiency |
5 |
| Timeline |
4 |
| Cross-Disease Value |
6 |
| Biomarker Enablement |
7 |
| Combinability |
6 |
| De-risking Value |
5 |
| Novelty |
6 |
- AD Knowledge Gap #18: What is the relationship between TBI and later AD?