Preclinical studies have shown that both free docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) cross the blood-brain barrier (BBB) through nonsaturable uptake mechanisms (10, 11, 12) and that a diet rich in n-3 PUFA reduces amyloid-beta (Aβ) (13, 14, 15, 16) and tau pathologies (16, 17), increases postsynaptic markers (15, 18, 19, 20), and improves cognitive performance (6, 14, 18) in several animal models of AD. The gene discussed is MAPT; the disease is Alzheimer disease.