Error unawareness as a driver of cognitive decline in individuals at risk for Alzheimer's disease.

Anosognosia, or unawareness of one's deficits, predicts faster clinical progression in Alzheimer's disease (AD), though its mechanisms remain unclear. We investigated five-year trajectories of response awareness and error-monitoring efficiency using second-order judgments from an annual word recognition memory task in cognitively unimpaired individuals at risk for AD from the INSIGHT-preAD cohort. Participants were divided into three groups according to amyloid status at baseline (positive, A + ; negative, A-) and clinical progression (controls, CTRL A+ or A-; and progressors, PROG). Task accuracy declined in PROG, while CTRL A+ showed continued learning, and CTRL A- remained accurate. Inefficient error-monitoring predicted subsequent performance decline in the PROG, with a strong interaction between accuracy and error-monitoring already at baseline. This effect was primarily driven by error unawareness. These findings provide first evidence that error unawareness - a core feature of anosognosia - may foster cognitive decline through the disruption of error-feedback learning mechanisms, potentially accelerating AD progression.