In neurodegenerative diseases, catechins cross the blood-brain barrier; their potent antioxidant capacity directly scavenges neurotoxic free radicals, inhibits Aβ amyloid aggregation and tau protein hyperphosphorylation, and suppresses aberrant activation of microglia and astrocytes along with the neurotoxic inflammatory factors they produce. The gene discussed is MAPT; the disease is neurodegenerative disease.