The findings of the present study and the previous studies provide new insights into the vital role of reduced chronic stress, resulting from reduced levels of phosphorylated ERK and JNK and HSP90 caused by B. breve MCC1274 supplementation, in alleviating neuropathological alterations, which involve reducing tau hyperphosphorylation, increasing synaptic density, and increasing neuronal activation, thus ameliorating memory impairment. The gene discussed is MAPT; the disease is memory impairment.