Color vision test to differentiate Alzheimer's disease from vascular dementia.

Arnaoutoglou et al. (2017) reported that "Ishihara Color Vision Test - 38 Plate" was useful for the differential diagnosis of dementia between Alzheimer's Disease (AD) and Vascular Dementia (VaD). The authors used sensitivity/specificity analysis, presenting 80.6% and 87.5% to discriminate AD and VaD patients when an optimal (32.5) cut-off value of performance was used. The authors cited a reference of the fact that AD patients suffered from a non-specific type of color blindness (Pache et al., 2003), and I have a query on their study with special reference to statistical method.