GFAP and depressive symptom measurement: Levels of GFAP were higher among individuals without incident depression than among those with depression (88.5 pg/mL and 83.1 pg/mL, respectively), NfL levels were similar among the two groups (15.9 pg/mL and 15.5 pg/mL, respectively), and p-tau181 levels were slightly higher among depression cases (1.1 pg/mL) than among individuals without depression (0.95 pg/mL).