The link between eye movements and cognitive function in mild to moderate Alzheimer's disease

This study investigated the relationship between eye movement parameters and cognitive function in patients with mild to moderate Alzheimer's disease (AD). A total of 80 patients with AD (mild and moderate) and 34 normal controls (NC) participated. Neuropsychological assessments were conducted using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA), while eye movements were recorded using eye-tracking technology. Comparisons of neuropsychological scores and eye movement parameters were made across the groups, and partial correlation analysis was performed to examine associations between eye movement metrics and specific cognitive domains. No significant differences were found among the groups in pursuit and fixation tasks. However, in pro-saccade tasks, patients in the moderate AD group exhibited significantly lower accuracy and longer latency compared to those in the mild AD and NC groups. Similarly, in anti-saccade tasks, the moderate AD group showed significantly lower accuracy and error correction rates compared to the other groups. Partial correlation analysis revealed that overall cognitive function was positively associated with the accuracy of pro-saccade and anti-saccade tasks, as well as the error correction rate of anti-saccade tasks, but negatively associated with pro-saccade latency. Further, orientation was negatively correlated with saccade latency and positively correlated with saccade accuracy, while visuospatial skills were positively associated with the accuracy of both saccade and anti-saccade tasks. A positive correlation was also observed between word fluency and both saccade accuracy and error correction rate. These findings indicate that eye movement parameters, particularly those related to saccade and anti-saccade tasks, are associated with various cognitive domains in mild to moderate AD patients. Eye-tracking technology may provide a convenient and non-invasive tool for assessing cognitive function and aiding in the diagnosis and evaluation of AD.