Patients with Mild Alzheimer’s Disease Fail When Using Their Working Memory: Evidence from the Eye Tracking Technique

Abstract

Patients with Alzheimer's disease (AD) develop progressive language, visuoperceptual, attentional, and oculomotor changes that can have an impact on their reading comprehension. However, few studies have examined reading behavior in AD, and none have examined the contribution of predictive cueing in reading performance. For this purpose we analyzed the eye movement behavior of 35 healthy readers (Controls) and 35 patients with probable AD during reading of regular and high-predictable sentences. The cloze predictability of words N - 1, and N + 1 exerted an influence on the reader's gaze duration. The predictabilities of preceding words in high-predictable sentences served as task-appropriate cues that were used by Control readers. In contrast, these effects were not present in AD patients. In Controls, changes in predictability significantly affected fixation duration along the sentence; noteworthy, these changes did not affect fixation durations in AD patients. Hence, only in healthy readers did predictability of upcoming words influence fixation durations via memory retrieval. Our results suggest that Controls used stored information of familiar texts for enhancing their reading performance and imply that contextual-word predictability, whose processing is proposed to require memory retrieval, only affected reading behavior in healthy subjects. In AD patients, this loss reveals impairments in brain areas such as those corresponding to working memory and memory retrieval. These findings might be relevant for expanding the options for the early detection and monitoring in the early stages of AD. Furthermore, evaluation of eye movements during reading could provide a new tool for measuring drug impact on patients' behavior.

Preliminary study of abnormalities in saccade dynamics in patients with hyperthyroidism with no pre‑existing eye damage

“…In medicine, eye-tracking systems are mainly applied in neuropsychology and ophthalmology research (24). In the fields of psychology and psychiatry, eye-tracking technology has recently been confirmed to be useful in diagnosing various diseases, including Parkinson's disease (25), Huntington's (26), abnormal gaze (27), nervous system degenerative diseases (28) and early Alzheimer's disease (29). Home eye-tracking systems can be used to follow up patients with vertigo (30).…”

Computational Techniques for Eye Movements Analysis towards Supporting Early Diagnosis of Alzheimer’s Disease: A Review

“…The cognitive status from participants is usually evaluated through neuropsychological tests, such as the Mini Mental State Examination (MMSE) [ 12 ]. However, some studies have used other techniques such as thyroid function test and magnetic resonance images [ 11 ] among others.…”

“…Recent literature reviews have outlined robust findings demonstrating that eye movements abnormalities are sign of cognitive decline [ 11 , 12 ] and can eventually be used to assess AD disease progression. Furthermore, current technology provides noninvasive equipment and methods to assess visual deficits ubiquitously and objectively in naturalistic scenarios [ 13 ].…”

Eye movement behavior identification for Alzheimer's disease diagnosis

“…As shown in, patients with early Alzheimer disease show changes during the execution of tasks such as reading [5]. These alterations can be related to an impairment in working memory [3,13]. It has been shown that it is possible to infer a diagnosis from this change in eye-movements [4].…”

“…Since AD is nonreversible, early treatment can improve a patient's life by delaying the full manifestation of the disease. In recent years, the study of eye movement during reading, known as eye-tracking, has proved helpful for performing this task [2][3][4][5].…”