P1‐460: How older adults with Alzheimer's disease allocate gaze during visual search
Maribel Pino, Anne‐Sophie Rigaud, Jocelyne de Rotrou, François Jouen · Alzheimer s & Dementia · 2011
Individuals living with Alzheimer's disease (AD) may encounter some difficulties in getting oriented in a new place, following a route to a familiar place or locating an object in an environment. All these tasks involve attentional processes and cognitive treatment of visual information. Primarily they are associated with eye movements. In this study we explore eye movement control during the visual scanning of daily life scenes in patients with AD or Mild Cognitive Impairment (MCI). The aim of this study is to help understanding of visual exploration strategies used by each subject group. Four groups of subjects were studied: young normal adults (YN; n = 40), middle-aged adults (MA; n = 40), older adults (OA; n =30), and patients with AD (AD; n = 40). Each participant completed two test-sessions. In the first one they were assessed with a standard neuropsychological battery, including visual acuity and contrast sensitivity testing. In the second one they underwent a set of visual search tasks on a computer. An infrared non-intrusive eye-tracker was used to record eye movements. Evaluation criteria included: task accuracy, initial saccade latency, scanning time and scanpath patterns. Preliminary results confirmed that there are differences in visual exploration strategies used by older adults with AD and MCI, and those employed by subjects in the two control groups (OA and YN). Participants in the AD and MCI groups would use less specific and less pragmatic exploration strategies, than those used the control groups. AD patients have longer reaction times and detect fewer targets than controls. Combined analysis of eye tracking and neuropsychological data shows that semantic memory and working memory play an important role in the tasks of visual attention. Comparison between age groups shows that information processing speed appears to be a very age-sensitive cognitive function. Non-invasive eye tracking technology provides a fresh insight into the difficulties related to attentional control encountered by older people with AD in the achievement of daily tasks. Understanding visual attention deficits in AD and in MCI will be useful to enhance environmental design for these disorders, and to develop cognitive training programs focused on these processes.