PTGS1 and Alzheimer disease: However,although a 6-month, double-blinded, placebo-controlled study with indomethacin,a preferential COX-1 inhibitor, appeared to protect AD patients from cognitivedecline [14], subsequentlarge-scale randomized clinical trials, mostly with selective COX-2 inhibitors,did not show any beneficial effects in AD patients with mild to severe symptoms[15-18].