When the type of therapy was taken into account, higher SOD activity was found in patients (PsO and AD together) that used methotrexate in comparison with patients that used local therapy, which could be explained in part by a compensatory increase in antioxidant enzymes activity (i.e., SOD) in patients with severe disease as compared with patients that used only local therapy. The gene discussed is SOD1; the disease is Alzheimer disease.