MAO-B which is the main isoform located in the brain preferentially oxidizes benzylamines, β-phenylethylamine (PEA) and polyamines.8 Tryptamine and dopamine which are basically dietary amines are generally effected by both enzyme isoforms.9 MAO plays an important role in the progression of several neurological diseases including AD. Here, MAOB is linked to Alzheimer disease.