Affiliations: [a] Department of Cognition, Development and Educational Psychology, University of Barcelona, Barcelona, Spain
| [b] Institute of Neurosciences of the University of Barcelona (UBNeuro), Barcelona, Spain
| [c] University of Guadalajara, Jalisco, México | [d] Department of Neurology and Neurophysiology, Hospital Sanitas CIMA, Barcelona, Spain
| [e] Braingaze SL, Mataró, Spain
| [f] Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
Correspondence:
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Correspondence to: Hans Supèr, Departament de Cognició, Desenvolupament i Psicologia de l’Educació, Fac Psicología, Universitat de Barcelona, Pg. Vall d'Hebron 171, 08035 Barcelona, Spain. Tel.: +34 933 125 158; E-mail: hans.super@icrea.cat.
Abstract: Background:Alzheimer’s disease (AD) is characterized by progressive deterioration of cognitive functions and may be preceded by mild cognitive impairment (MCI). Evidence shows changes in pupil and vergence responses related to cognitive processing of visual information. Objective:Here we test the hypothesis that MCI and AD are associated with specific patterns in vergence and pupil responses. Methods:We employed a visual oddball task. In the distractor condition (80%of the trials), a blue stimulus was presented whereas in the target condition (20%of trials) it was red. Participants (23 Controls, 33 MCI patients, and 18 AD patients) were instructed to press a button when a target appeared. Results:Participants briefly converged their eyes 200 ms after stimulus presentation. In controls, this transient peak response was followed by a delay response to targets but not to distractor stimuli. In the patient groups, delay responses to distractors were noticed. Consequently, the differential vergence response was strong in the control group, weak in the MCI group, and absent in the AD group. Pupils started to dilate 500–600 ms after the appearance of a target but slightly contracted after the presentation of a distractor. This differential pupil response was strongest in the AD group. Conclusion:Our findings support the idea of a role of vergence and pupil responses in attention and reveal altered responses in MCI and AD patients. Further studies should assess the value of vergence and pupil measurements as an objective support tool for early diagnosis of AD.
