Background Abnormalities in eye movement metrics have been related to cognitive decline in dementia (Garbutt et al., 2008; Crawford et al., 2005), however, little is known about its association with executive dysfunction prior to the onset of Alzheimer’s disease (AD). The objective of this study was to determine whether older adults with mild cognitive impairment (MCI) or incipient dementia due to AD display subtle signs of impairment in executive functioning as compared to healthy controls, through the analysis of eye movement behavior. Method 93 elderly individuals were allocated into three groups according to cognitive status: normal controls (CTRL, n=28), mild cognitive impairment (n=44) and Alzheimer’s disease (n=21). All groups were tested with an eye tracking‐assisted protocol composed of a prosaccade (PS) and an anti‐saccade (AS) task. The PS task required a fast, automatic saccade towards a peripheral target stimulus. In the AS task (measure of executive functioning), subjects had to inhibit an prosaccade towards the target stimulus and initiate a voluntary saccade in the opposite direction. Result The PS task revealed a similar saccadic performance across the three groups. The AS task had a greater impact on the frequency and latency of eye movement metrics in each group, with AD subjects showing a greater executive decline than CTRL and with MCI group performing intermediately. MCI were similarly impaired as AD in their voluntary saccadic reaction times, with a longer time to correct erroneous saccades. Correlations revealed relationships between eye movement metrics in the AS and measures of inhibitory control, attention, working memory and self‐monitoring. Conclusion The three groups showed a similar pattern of eye movements in the PS task, with both patients groups revealing a preserved automatic saccadic control compatible with the pattern observed in healthy ageing. AS task confirmed that cognitive impairment in the MCI‐AD continuum affects eye movement patterns reflecting executive deficits in inhibitory control, working memory and executive‐attention control subjacent to voluntary saccades. MCI revealed an intermediary impairment in these executive domains, as compared to AD (highest impairment) and CTRL. However, they showed significant increased response times similar to AD subjects, in order to overcome these deficits.

The ABCD battery is a useful tool in the evaluation of adults and elderly with DS and the performance of individuals in this battery correlates with indices of functionality. This is a pioneer study in Brazil, and it points to the need for a better characterization of the linguistic abilities of individuals with DS, in order to allow the elaboration of strategies that stimulate their communicative abilities as to promote greater social insertion for this population.

Background: The assessment of language changes associated with visual search impairment can be an important diagnostic tool in the Alzheimer’s disease (AD) continuum. Objective: Investigate the performance of an eye-tracking assisted visual inference language task in differentiating subjects with mild cognitive impairment (MCI) or AD dementia from cognitively unimpaired older adults (controls). Methods: We assessed a group of 95 older adults (49 MCI, 18 mild dementia due to AD, and 28 controls). The subjects performed the same task under multiple experimental conditions which generate correlated responses that need to be taken into account. Thus, we performed a non-parametric repeated measures ANOVA model for verbal answers, and a linear mixed model (LMM) or its generalized version for the analysis of eye tracking variables. Results: Significant differences were found in verbal answers across all diagnostic groups independently of type of inference, i.e., logic or pragmatic. Also, eye-tracking parameters were able to discriminate AD from MCI and controls. AD patients did more visits to challenge stimulus (Control-AD, –0.622, SE = 0.190, p = 0.004; MCI-AD, –0.514, SE = 0.173, p = 0.011), more visits to the correct response stimulus (Control-AD, –1.363, SE = 0.383, p = 0.002; MCI-AD, –0.946, SE = 0.349, p = 0.022), more fixations on distractors (Control-AD, –4.580, SE = 1.172, p = 0.001; MCI-AD, –2.940, SE = 1.070, p = 0.020), and a longer time to first fixation on the correct response stimulus (Control-AD, –0.622, SE = 0.190, p = 0.004; MCI-AD, –0.514, SE = 0.173, p = 0.011). Conclusion: The analysis of oculomotor behavior along with language assessment protocols may increase the sensitivity for detection of subtle deficits in the MCI-AD continuum, representing an important diagnostic tool.

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