Tadokoro K, Yamashita T, Fukui Y, et al. - Whether a novel and short (3 min) eye tracking device is useful for assessing the cognitive function of normal control (NC, n = 52), mild cognitive impairment (MCI, n = 52), and Alzheimer disease (AD, n = 70) patients, was inquired herein. Not only was eye tracking total score reduced significantly in MCI and AD but also it displayed good correlation with the mini-mental state examination score. Effective discrimination of NC, MCI and AD was enabled by the eye tracking test, particularly by memory and deductive reasoning tasks. Overall, the present novel eye tracking test is beneficial for early identification of MCI and AD in screening, as this test clearly differentiated cognitive functions among NC, MCI, and AD participants in this study.