Vertical and Horizontal Saccades in Aging and Dementia: Failure to Inhibit Anticipatory Saccades

Abstract

Vertical And Horizontal Saccades To Visual Stimuli Were Compared In Young And Elderly Control Subjects And Elderly Patients With A Dementia Of Alzheimer's Type. Aging Was Associated With Long Latency, Accurate Saccades In Both Directions. The Vertical But Not Horizontal Peak Velocity For Ten Deg Saccades Was Mildly Reduced In The Elderly Control Subjects Suggesting A Selective Vulnerability Of The Vertical Saccade System To Aging.

Dementia Of An Alzheimer's Type Was Associated With An Additional Prolongation Of Saccade Latency And A Reduction Of Saccade Accuracy. The Peak Velocity 3-15 Deg Saccades In Demented Patients Were Similar To The Elderly Control Subjects. Anticipatory Saccades Occurring Prior To Target Displacement Were Particularly Prominent In The Demented Patients And Could Not Be Consistently Suppressed. Long Latency, Hypometric Visually Guided Saccades Accompanied By An Inability To Suppress Anticipatory Saccades Is Characteristic Of Dementia Of An Alzheimer's Type. The Magnitude Of These Abnormalities Is Similar In The Horizontal And Vertical Directions And Is Not Significantly Correlated With The Severity Of The Dementia.

Key Words:

• Dementia
• Eye Movements
• Saccade
• Alzheimer's Disease Prediction
• Anticipation