Tracking the eyes to track decline: Global eye movement similarity as a novel neuropsychological marker of mild cognitive impairment

INTRODUCTION: Across two studies, we investigated whether global eye movement similarity reflects visuospatial memory impairment in older adults, aiming to identify a novel neuropsychological marker of mild cognitive impairment (MCI). METHODS: In Study 1, 35 participants completed a global eye movement similarity memory (GEMS-M) task, viewing indoor scene images with three objects and identifying changes during the recognition phase. In Study 2, 60 participants (30 healthy controls, 30 with MCI) completed a passive version of the task without explicit memory judgment. RESULTS: Study 1 showed that the similarity of global eye movement patterns between encoding and recognition phases predicted memory performance, particularly when an object was added. Study 2 demonstrated that global eye movement similarity, combined with demographics, discriminated MCI patients from healthy controls with an AUC of 0.93. DISCUSSION: Our findings suggest that global eye movement similarity may serve as a promising tool for the early detection of MCI.