Fig. 1.

Experimental timeline. Subjects were seen once before diagnosis (first visit; time = 0). At that time, for those who agreed to participate to the study, two blood samples were obtained: one for routine diagnostic tests; the other for zonulin concentration assay. The collected samples were all analysed in a blinded condition, with no connection to the patients’ diagnosis. Patients and controls were subsequently divided into the different groups (diagnosis; time 1). The aMCI group was the only one to undergo a follow-up evaluation, which was of variable length depending on the time of the enrolment. Over a 32-month median follow-up, we identified two subsets of aMCI patients: those who progressed to overt dementia; or those who remain stable (Sub-diagnosis aMCI; time 2). Finally, the levels of zonulin were assigned to the corresponding patients/group and analysed (Data analysis; time 3)