NEFL and Cognitive impairment: Plasma concentrations of NfL, BDNF, and NfL/BDNF ratio were significantly affected by the severity of cognitive impairment (F2,56 = 3.545, p = 0.036, ηp2 = 0.112; F2,34 = 7.284, p = 0.002, ηp2 = 0.294; F2,35 = 6.108, p = 0.005, ηp2 = 0.259, respectively).