Eye Movements in patients with Alzheimer's disease and mild cognitive impairment

In this study, it was aimed to compare the prosaccade, antisaccade, microsaccade and visual scanning measurements in Alzheimer's disease (AD) and mild cognitive impairment (MCI) with healthy controls (HC). The study included 30 AD and 32 MCI patients and 32 HC who applied to Dokuz Eylül University Department of Neurology. Eye movements of the participants, prosaccade, antisaccade, microsaccade and visual scanning measurements were made with an eye-tracking device; cognitive functions were evaluated with neuropsychological tests evaluating the general cognitive status, attention, memory, executive functions, visuospatial functions and language domains. Compared to HC, an increase in prosaccade latency and a decrease in the number of correct saccades were observed in AD. Patients with AD and MCI, MCI and HC are similar in terms of prosaccade measurements. It was found that the corrected saccade, anticipatory saccade, express saccade, uncorrected error and latency of AD patients were increased than HC, and the correct saccade number and amplitude were decreased. Compared to MCI, AD showed an increase in the corrected saccade, anticipatory saccade, uncorrected error and latency and a decrease in the correct saccades. An increase in the uncorrected error was observed in MCI compared to HC. While a decrease in the frequency and amplitude of microsaccades was observed in AD compared to HC, AD and MCI and MCI and HC were found to be similar. In AD, the number of fixations and saccades decreased in visual scanning compared to HC. The AD and MCI and HC and MCI groups did not differ in terms of visual scanning. Eye movement measurements were associated with global cognition, attention, memory, executive functions, visuospatial functions and language. AD showed eye movement abnormalities in prosaccade, antisaccade, microsaccade and visual scanning measurements compared to HC. Eye movements can be used as a possible clinical assessment tool to distinguish AD from MCI and HC.