Saccadic abnormalities in frontotemporal dementia

Abstract

To characterize saccadic eye movements, as a marker of decision-making processes, in frontotemporal dementia (FTD). Saccadometry was performed on a cross-section of patients with FTD, using a portable saccadometer, and results compared to matched control subjects. We used the Linear Approach to Threshold with Ergodic Rate model to generate measures of decision-making speed and incidence of early saccades. Patterns of cortical atrophy were related to decision-making processes using voxel-based morphometry (VBM) analysis. A total of 45 subjects (22 FTD: 10 with behavioral variant FTD and 12 with primary progressive aphasia, and 23 controls) were studied. A measure of decision-making speed, μ, was reduced in FTD, resulting in prolonged saccadic latency, but the incidence of early saccades was increased compared to controls. In addition, performance on an antisaccade task was poor in FTD compared to controls. Decision-making speed and the incidence of early saccades were independently correlated with atrophy of the left frontal eye field, and decision-making speed also correlated with atrophy of the left cingulate eye field. Saccades are abnormal in FTD, reflecting reduced decision-making speed, and these abnormalities related to atrophy of the left frontal eye field. In addition, patients with FTD had an increased incidence of early saccades, which may be due to reduced inhibition of primitive responses.