Walsh & Hoyt: Abnormal Eye Movements and Dementia

Patients with various dementing processes have abnormal eye movements, reflecting either disturbances in cerebral cortical structures or in other subcortical structures that may also be affected by that particular disease. Excessive errors on the antisaccade test, particularly when associated with a ""visual grasp reflex,"" are a useful indicator of an organic process when pseudodementia is a diagnostic consideration in a patient with a possible cognitive decline. Patients with Alzheimers disease have excessive numbers of square-wave jerks and defects in saccade latency and, occasionally, accuracy and velocity. Alzheimers patients show longer mean fixation durations and a reduced number of exploring saccades when viewing simple but not complex scenes, perhaps reflecting a motivation deficit. Impaired predictive tracking and excessive number of anticipatory saccades are a feature of Alzheimers disease, as is difficulty generating saccades during reading. Eye movements may be used to monitor higher-level processes, such as ""curiosity,"" by looking at exploratory behavior (visual search and scan paths) while a subject views novel visual stimuli. This capability too appears to be diminished in Alzheimers patients. Impairment of spatially directed attention may also be reflected in eye movement abnormalities, and a Balint-like syndrome may develop. Pursuit abnormalities also occur in Alzheimers patients.