Some flavonoids such as luteolin, apigenin, and myricetin increase the tyrosine hydroxylase activity and the dopamine level in the brain, which is very important in the case of Parkinson’s disease, while a decrease in the BACE-1 activity by chrysin, catechins, quercetin, eriodyctiol, and biochanin A is crucial for reducing amyloid-β aggregation during the development of Alzheimer’s disease. This evidence concerns the gene BACE1 and Parkinson disease.