Plasma TACE activity in subjects with mild cognitive impairment and patients with AD is known to be increased.17, 18, 19 Because TACE is the main cleaving enzyme of p75NTR,20, 21 it is reasonable to suggest that a higher TACE activity would generate a higher level of p75NTR-ECD in the serum in AD. Here, NGFR is linked to Alzheimer disease.