COX4I1 and Alzheimer disease: We recently reported that icariin treatment significantly recovered the learning-memory deficits in triple-transgenic (3× Tg) AD mice, and we found that icariin could enhance the level of brain metabolite N-acetylaspartate (NAA), increase the production of adenosine triphosphate (ATP) and the expression of mitochondrial proteins pyruvate dehydrogenase-E1α (PDHE1α) and cytochrome c oxidase IV (COX IV) in AD mouse brain, which reveals an important role of icariin in the regulation of mitochondrial metabolism against AD [32].