Epidemiological data show that non-steroidal anti-inflammatory drugs delay the clinical features of AD,32 but clinical trials have failed.33 Perhaps this is because the drugs were COX inhibitors and, as shown here, the most toxic aspect of Aβ-induced inflammation is mediated by 5-LOX metabolites, whereas the COX metabolites PGE2 and PGD2 are neuroprotective. This evidence concerns the gene ALOX5 and Alzheimer disease.