Oculomotor Abnormalities during Reading in the Offspring of Late-Onset Alzheimer’s Disease

Abstract

Introduction: Eye movement patterns during reading are well defined and documented. Each eye movement ends up in a fixation point, which allows the brain to process the incoming information and to program the following saccade. In this work, we investigated whether eye movement alterations during a reading task might be already present in middle-aged, cognitively normal offspring of late-onset Alzheimer’s disease (O-LOAD). Methods: 18 O-LOAD and 18age-matched healthy individuals with no family history of LOAD participated in the study. Participants were seated in front of a 20-inch LCD monitor and single sentences were presented on it. Eye movements were recorded with an eye tracker, with a sampling rate of 1000 Hz. Results: Analysis of eye movements during reading revealed that O-LOAD displayed more fixations, shorter saccades and shorter fixation durations than controls. Conclusion: The present study shows that O-LOAD evidenced alterations in their eye movements during reading. O-LOAD eye movement behavior could be considered an initial sign of oculomotor impairment. Hence, evaluation of eye movement during reading might provide a useful tool for monitoring well-defined cognitive resources.