Here, we investigated whether plasma biomarkers (Aβ42/40 ratio, p‐tau181, GFAP, and NfL) are associated with several digital online cognitive metrics, measuring visual short‐term memory, long‐term memory, visuospatial copying, executive function, and processing speed in a cohort of patients with AD and two samples of elderly healthy controls, one of which also underwent blood collection for plasma biomarker measurement. Here, GFAP is linked to Alzheimer disease.