We aimed here to investigate how plasma GFAP, NfL, p‐tau181, and Aβ42/40 are associated with (1) performance on five cognitive domains at baseline, (2) cognitive decline on five cognitive domains over a 2‐year follow‐up period, and (3) functional independence in activities of daily living (ADL) at baseline, all across and within multiple neurodegenerative and cerebrovascular diseases. This evidence concerns the gene GFAP and Mental deterioration.