The Performance of Saccade Tasks Correlates with Cognitive Test Scores in Elderly Population: Evidence for the Usefulness of Oculomotor Tests in Cognitive Assessment

Abstract

Background: Among the elderly, dementia is a common and disabling disorder with primary manifestations of cognitive impairments. Diagnosis and intervention in its early stages is the key to effective treatment. Nowadays, the test of cognitive function relies mainly on neuropsychological tests, such as the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). However, they have noticeable shortcomings, e.g., the biases of subjective judgments from physicians and the cost of the labor of these well-trained physicians. Thus, advanced and objective methods are urgently needed to evaluate cognitive functions. Methods: We developed a cognitive assessment system through measuring the saccadic eye movements in three tasks. The cognitive functions were evaluated by both our system and the neuropsychological tests in 310 subjects, and the evaluating results were directly compared. Results: In general, most saccadic parameters correlate well with the MMSE and MoCA scores. Moreover, some subjects with high MMSE and MoCA scores have high error rates in performing these three saccadic tasks due to various errors. The primary error types vary among tasks, indicating that different tasks assess certain specific brain functions preferentially. Thus, to improve the accuracy of evaluation through saccadic tasks, we built a weighted model to combine the saccadic parameters of the three saccadic tasks, and our model showed a good diagnosis performance in detecting patients with cognitive impairment. Conclusion: The comprehensive analysis of saccadic parameters in multiple tasks could be a reliable, objective, and sensitive method to evaluate cognitive function and thus to help diagnose cognitive impairments.