This challenge targets the hypothesis: **APOE4 astrocytes exhibit impaired cholesterol efflux via ABCA1/ABCG1 transporters, driving intracellular lipid droplet accumulation and secondary neuronal cholesterol deficiency** **Hypothesis Summary:** ## Mechanistic Overview APOE4 astrocytes exhibit impaired cholesterol efflux via ABCA1/ABCG1 transporters, driving intracellular lipid droplet accumulation and secondary neuronal cholesterol deficiency starts from the claim that modulating ABCA1, ABCG1 within the disease context of neuroscience can redirect a disease-relevant process. The original description reads: "**Molecular Mechanism and Rationale** The APOE4 allele represents the strongest genetic risk factor for late-onset Alzheimer's dis **Falsifiable Predictions:** 1. Pharmacological modulation of ABCA1 will alter neuroscience markers in validated models by ≥20% 2. Genetic knockdown of the key target will reproduce the pathological phenotype in ≥2 independent model systems 3. Patient-derived biosamples will show the predicted molecular signature (sensitivity ≥70%, specificity ≥70%) 4. Mechanistic intervention at the proposed node will rescue neuronal viability in vitro by ≥30% **Bounty Tier:** $125,772 USD (composite score 0.758) **Challenge Type:** Open — any team may submit experimental evidence supporting or refuting this hypothesis **Success Criteria:** Peer-reviewed evidence demonstrating mechanistic validation of ≥2 of the 4 predictions, with independent replication.