Evidences of mild Alzheimer?s disease diagnosis from eye movement analysis during reading.

MANES FACUNDO; FERNANDEZ GERARDO; CASTRO LILIANA; SCHUMACHER MARCELA; OROZCO DAVID; AGAMENNONI OSVALDO

Londres

Conferencia; The Lancet Neurology Conference; 2016

The Lancet

Background Patients with Alzheimer disease (AD) develop progressive language, visuoperceptual, attentional, and oculomotor changes that can have an impact on their reading comprehension even in the earliest stage.The aim of the present study is to develop an objective, noninvasive and economic evaluation of Mild Cognitive Impairment (MCI) that, in a longitudinal studies, could contribute to achieve mild Alzheimer disease diagnosis.Methods The study was done in the Universidad Nacional del Sur with the collaboration of Hospital Municipal and Clinica Privada; Bahia Blanca, Argentina.We analyzed the eye movement behavior using an eyetracker during reading Spanish regular and highly-predictable sentences.The control group consisted of 35 elderly adults (24 Female and 11 Male), mean 70 years old (SD=6.2), with no known neurological and psychiatric disease and no evidence of cognitive decline or impairment in daily activities. The AD group; consisted of 22 Females, 13 Males; mean 68 years old (SD=6.4). The diagnosis of probable AD were based on DSM-IV. All AD patients underwent a detailed clinical history, physical/neurological examination and thyroid function test. Patients were excluded if they suffered from any medical conditions that could interfere with, their cognitive decline.Using the eye movement information data and lineal mixed models we analyzed the effects of previous words properties (predictability, length, frequency) in the gaze and fixation duration. FindingsIn Controls, changes in predictability significantly affected fixation duration along the sentence; noteworthy, these changes did not affect fixation durations in AD patients (t-value>3.5).Contextual-word predictability, whose processing require memory retrieval, only affected reading behavior in healthy subjects. In AD, this loss might reveal 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.