COMT and Alzheimer disease: As shown in Figure 7A, the retrieved Alzheimer’s disease-related proteins were clustered into five groups according to their signaling pathways involved in the pathogenesis and/or the pathophysiology of the disease: (i) the enzymatic degradation of dopamine by monoamine oxidase and by COMT; (ii) the signaling mediated by receptor tyrosine kinases; (iii) the amyloid fiber formation; (iv) the interleukin-10 signaling pathway; and (v) the degradation of the extracellular matrix.