Changes in visual fixation and saccadic eye movements in Alzheimer's disease

Visual fixation and saccadic eye movements were assessed in 31 mild to moderately demented patients with probable Alzheimer's disease (AD) and 31 age- and education-matched nondemented elderly control subjects. Seventeen AD and 17 matched control subjects were reassessed after a 9-month interval. On a fixation task, duration of fixation and number of intrusive saccades were not different between groups at baseline or follow-up. Both AD patients and control subjects showed more intrusive saccades at follow-up than at baseline. AD patients showed increased latency to initiation of saccades at baseline and on follow-up. Amplitude and velocity of saccades were not different between groups at any visit. Changes in measures of fixation, but no saccade measure, correlated with changes in MMSE scores over testing sessions. These data suggest that fixation is more sensitive than are saccades to the progression of AD.