Saccadic Eye Movements May Serve as Biomarkers for Mild Cognitive Impairment

The gaze-analyzing perimeter (GAP) is a device available outside the US that performs perimetry through the use of eye tracking indicators. In this study, even after adjusting for possible confounders, saccadic eye movement parameters obtained using GAP were significantly associated with MCI, suggesting that saccadic eye movement parameters, particularly mean reaction time, may serve as biomarkers for identifying MCI. Photo: Findex. Click image to enlarge. The early identification of mild cognitive impairment (MCI) is crucial for preventing dementia progression, making reliable cognitive screening tools essential. In a recent study, researchers examined the relationship between saccadic eye movement parameters and MCI using a gaze-analyzing perimeter (GAP) in a large Japanese cohort. Their results were recently published in Ophthalmology Science. Unlike in traditional perimetry, a GAP device conducts perimetry by presenting a target to be tracked by the subject. Note that this study was funded by a manufacturer of such a device (Findex) and its device was used in the testing.The study analyzed 1,202 individuals (aged ≥59) from the Nagahama Prospective Cohort, with 557 (46.3%) identified as having MCI based on the Japanese version of the Montreal Cognitive Assessment (MoCA-J). Subjects were divided into the MCI and non-MCI groups based on a MoCA-J score threshold of 25. The researchers used GAP, a head-mounted, space-saving eye-tracking device, to measure five saccadic parameters precisely without large equipment or dark rooms: reaction time, latency, number of saccades, first gain and end gain. Genome wide association studies were performed for reaction time.Longer reaction time, longer latency and smaller end gain were significantly associated with MCI.The extent of involvement of each visual area in each part of saccadic eye movement remains unclear. Therefore, reaction time, which comprehensively reflects whole saccadic eye movement, may be more useful than the existing subdivided saccadic parameters in screening for mild cognitive impairment, the authors noted in their paper.“Latency can be understood as the time to determine whether to initiate saccadic movement, reflecting important aspects of cognitive function such as decision-making and planning ability, which may deteriorate after the earlier stages of cognitive dysfunction,” the researchers wrote in their paper. “Given that, it is not surprising that latency is prolonged in patients with MCI.” The authors found it intriguing that among the parameters related to the accuracy of saccadic eye movements, only end gain remained significantly associated with MCI after multivariate adjustment in the current study. “This finding suggests that even if individuals without cognitive impairment fail to direct their gaze near the target on the initial saccade, they can repeatedly correct their trajectory and eventually bring their gaze close to the target. In contrast, the MCI group exhibits impaired accuracy in achieving this adjustment,” the authors wrote.A genome-wide significant association was identified between reaction time and rs1991348, a SNP located near the RALYL gene. “This is particularly compelling given that RALYL has been reported as a hub gene associated with Alzheimer's disease reserve; individuals with higher RALYL expression are reported to exhibit greater cognitive reserve in Alzheimer's disease, meaning that despite underlying Alzheimer's disease pathology, their cognitive function remains relatively preserved,” the authors wrote in their paper. “While our study does not establish a causal relationship between reaction time and cognitive function, we speculate that reaction time may serve as a novel biomarker for cognitive reserve and, by extension, may also be closely linked to MCI.”The researchers concluded the paper by noting that the number of people with cognitive impairment is expected to increase, making early detection and intervention of cognitive impairment more important than ever before. The GAP device, they say, offers practical advantages over traditional neuropsychological tests, including workflow efficiency and reduced testing time, making it potentially suitable for outpatient or community settings. “In this context, the ability to conduct simple cognitive screening through the evaluation of saccadic eye movement using a space-saving and easily accessible tool, such as GAP, would be extremely valuable,” the authors wrote in their paper.Click here for the journal source. Nakano E, Mori Y, Morino K, et al. The association between saccadic eye movement and mild cognitive impairment: the Nagahama Study. Ophthalmology Sci. June 22, 2026. [Epub ahead of print.] This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.