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S. M. Pepin, A. Saykin, H. A. Wishart, R. Santulli, R. Newman; Visual Contrast Sensitivity Assessment in Early Stages of Alzheimer's Disease: A Preliminary Study Using Frequency Doubled Technology. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1194.
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The goal of this study was to gain pilot data on whether the Welch Allyn Frequency Doubling Technology (FDT2 model) is sensitive to early/preclinical stages of Alzheimer’s disease (AD).
A cross-sectional study design was employed to compare the FDT test variables between healthy controls, mild AD patients and amnestic AD patients. 6 mild AD patients, 6 amnestic MCI patients and 6 healthy controls were recruited for the study. After exclusions and re-testing, 5 patients with early AD, 4 patients with amnestic MCI and 5 healthy demographically comparable older controls. Many participants were examined twice to address technical issues and confirm initial results.
The FDT2 data were analyzed independently by two groups. Analysis by one statistician indicated that several variables appeared promising as discriminators of the three diagnostic groups (AD, MCI, HC-healthy controls): AD v. HC: test time (p=0.0031), peripheral/central (p=0.0034), mean deviation (average loss of entire field) (p=0.0118), and pattern standard deviation (irregularity in visual field) (p=0.0128).
The variables of average loss of entire visual field, irregularity in the visual field and test taking time appear promising as discriminators of AD, MCI and HC. A further phase of the study will increase the number of participants to be sufficient for multivariate analysis. It was determined that in the next phase of the study a sample of 30 HC, 30 MCI, and 30 early AD would be sufficient for multivariate analysis combining these or other FDT2 features as predictors of class membership.
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