CA2 and Alzheimer disease: For instance, a decrease of carbonic anhydrases (CAs) activity and a series of proteins excessively nitrated and/or carbonylated, including the isoform CA II, have been described in the AD hippocampus [11,12,13,14] and in brain samples obtained from mild cognitive impairment patients (MCI), suggesting that the increase in oxidative modifications dropped the enzyme catalytic activity during the preclinical AD stages [15].