Age-related trends in saccade characteristics among the elderly

Eye movement recordings are useful for assessing neurological disorders, the prevalence of which increases with age. However, there is little rigorous quantitative data on describing oculomotor changes that occur during healthy aging. Here, we measured the ability of 81 normal elderly subjects (60-85 years) to perform two saccadic eye movement tasks: a pro-saccade task, requiring an automatic response to look towards a stimulus and an anti-saccade task, requiring inhibition of the automatic response to instead initiate a voluntary saccade away from the stimulus. Saccadic ability decreased with age: the oldest subjects were slower to initiate saccades and they made more direction errors (i.e., erroneous pro-saccades) in the anti-saccade task. Intra-subject variability in reaction time also correlated positively with age in both saccade tasks. Voluntary saccade control, as assessed by the anti-saccade task, was far more affected by aging than automatic control, as assessed by the pro-saccade task, suggesting that the mechanisms driving voluntary and automatic saccade performance deteriorate at different rates in the aging brain, and therefore likely involves different neural substrates. Our data provide insight into deficits due to normal brain changes in aging as well as a baseline to evaluate deficits caused by neurological disorders common in this age range.