BACE1 and Alzheimer disease: Using the log-rank test in the AD model compared to the untreated APP-BACE1 control, no significant variations in lifespan were observed in the Lf5221 group (p>0.05) while the TFLA (p<0.05), probiotic (p<0.05) and synbiotic (p<0.05) groups all significantly improved survivability (S1 Fig).