Saccade impairments in patients with fronto-temporal dementia.

Abstract

Early diagnosis of fronto-temporal dementia (FTD) is often difficult because of the non-specific presentation. Saccadic eye movements, which are mainly controlled by the frontal areas, may provide a powerful tool for the analysis of frontal lobe dysfunction. The pattern of saccadic abnormalities has not previously been investigated in patients with FTD. To study saccade tasks in a group of 23 patients with FTD and compare the results with aged matched healthy controls. Triggering and inhibition of reflexive prosaccades were evaluated in a prosaccade and an antisaccade task, respectively, while the ability to withhold an antisaccade during a delay was explored in a delayed antisaccade task. Patients with progressive supranuclear palsy (PSP), in whom the pattern of eye movement deficit is well documented, were studied with the same protocol. To characterise the frontal lobe dysfunction in FTD more precisely, a battery of neuropsychological tests was carried out in these patients. Patients with FTD showed impaired reflexive saccade inhibition, similar to that observed in patients with PSP, and a decreased ability to withhold an antisaccade. Inhibition of reflexive and voluntary saccades appears to be independently processed. A delayed antisaccade task could be useful for the early diagnosis of FTD.