RBFOX3 and amyloidosis: In contrast, we detected a small, but significant decrease in NeuN+ neurons within both CA1 and the parietal cortex of hPS‐5X chimeric mice, suggesting that at 6 months of age, the combination of amyloid and tau pathology promotes neuronal death in hPS‐5X mice (Figure 2K, L; Figure S1K, L).