Spectrum of Saccade System Function in Alzheimer Disease | Dementia and Cognitive Impairment | JAMA Network
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Original Contribution
September 2003

Spectrum of Saccade System Function in Alzheimer Disease

Author Affiliations

From the Neuropsychology Research Laboratory, Alzheimer's Disease Research Group, The Mental Health Research Institute of Victoria, Parkville (Ms Shafiq-Antonacci, Drs Maruff and Currie and Mr Masters); School of Biophysical Sciences and Electrical Engineering, Swinburne University of Technology, Hawthorn (Ms Shafiq-Antonacci); Department of Psychological Sciences, La Trobe University, Melbourne (Dr Maruff); and Department of Pathology, The University of Melbourne, Parkville (Mr Masters); Victoria, Australia. Dr Currie is now affiliated with the Brain Research Institute, Drug and Alcohol Services, Westmead Hospital, Westmead, New South Wales, Australia.

Arch Neurol. 2003;60(9):1272-1278. doi:10.1001/archneur.60.9.1272

Background  In Alzheimer disease (AD), tests of "first-order capabilities," such as reaction time or motor ability, might measure central nervous system integrity or disability more reliably than those of abstract, conceptual, or cognitive behavior. Saccade system impairments are present in AD, but their sensitivity or specificity remains unevaluated.

Objectives  To determine sensitivity and specificity of saccade measures for AD, precise impairments in AD, and the relationship between dementia severity and saccade system function.

Design  Case-control study comparing saccade system function between patients and control subjects, including correlations between saccade system function and dementia severity in patients and standardized scores examining impairment in individual patients.

Setting  Neuropsychiatric research institute.

Participants  Two hundred forty-five healthy volunteers from the general population, and 35 patients with AD referred by memory clinics. Age- and sex-matched controls were compared with patients on random saccade (n = 35), predictive saccade (n = 11), and antisaccade (n = 18) tasks.

Main Outcome Measures  Saccade latencies, velocities, and accuracies and antisaccade error rates. Sensitivity, specificity, and predictive positive and negative values were calculated using all control data.

Results  Patients had longer and more variable latencies, more hypometric and anticipatory random saccades, and higher antisaccade error rates (P<.01 for all comparisons). The antisaccade error rate correlated with dementia severity (Spearman r = −0.59, P = .02). Antisaccade measures were the most specific (0.70-0.90) and random saccade gain the most sensitive (0.87).

Conclusions  Despite AD group impairment, individual patients function within the control range, reducing the sensitivity and specificity of saccade measures for AD. Longitudinal evaluation may provide more reliable classification.