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

Published online by Cambridge University Press:  19 June 2017

Tomoyuki Kawada Open the ORCID record for Tomoyuki Kawada [Opens in a new window]
Tomoyuki Kawada*
Affiliation:
Department of Hygiene and Public Health, Nippon Medical School, Tokyo, Japan
*
E-mail: kawada@nms.ac.jp
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Extract

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.

Type
Letter to the Editor
Information
International Psychogeriatrics , Volume 29 , Issue 10 , October 2017 , pp. 1753
Copyright
Copyright © International Psychogeriatric Association 2017 

Arnaoutoglou et al. (Reference Arnaoutoglou2017) 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., Reference Pache2003), and I have a query on their study with special reference to statistical method.

Although their statistical approach is fundamentally correct, insufficient values of positive and negative predictive values show inadequate screening tools to discriminate AD and VaD patients. In addition, the Receiver Operating Characteristic (ROC) curve analysis by shifting cut-off value for drawing ROC curves and calculating area under the curve is another important method for the differentiation (Hanley and McNeil, Reference Hanley and McNeil1982, Reference Hanley and McNeil1983).

Second, Takeda et al. (Reference Takeda, Tajime and Nakagome2010) evaluated the screening ability for 91 patients with mild AD by using Takeda three colors combination test (TTCC). They set a 75 control subjects and logistic regression analysis was adopted. Odds ratio (95%CI) was 32.0 (13.1–78.1), and concluded that TTCC was effective for screening mild AD. Anyway, the setting of control group in study by Arnaoutoglou et al. (Reference Arnaoutoglou2017) seems not effective, and sensitivity/specificity analysis alone is not satisfactory to confirm “Ishihara Color Vision Test – 38 Plate” as the adequate screening tool to discriminate AD and VaD patients.

Conflicts of interest

None.

References

Arnaoutoglou, N. A. et al. (2017). Color perception differentiates Alzheimer's Disease (AD) from Vascular Dementia (VaD) patients. International Psychogeriatrics, 29, 1357–1363. doi: 10.1017/S1041610217000096.CrossRefGoogle ScholarPubMed
Hanley, J. A. and McNeil, B. J. (1982). The meaning and use of the area under a receiver operating characteristic (ROC) curve. Radiology, 143, 29–36. doi: 10.1148/radiology.143.1.7063747.CrossRefGoogle Scholar
Hanley, J. A. and McNeil, B. J. (1983). A method of comparing the areas under receiver operating characteristic curves derived from the same cases. Radiology, 148, 839–843. doi: 10.1148/radiology,148.3.6878708.CrossRefGoogle ScholarPubMed
Pache, M. et al. (2003). Colour vision deficiencies in Alzheimer's disease. Age and Ageing, 32, 422–426.CrossRefGoogle ScholarPubMed
Takeda, S., Tajime, K. and Nakagome, K. (2010). The takeda three colors combination test: an easy and quick screening for Alzheimer's disease. Journal of the American Geriatrics Society, 58, 1199–1200. doi: 10.1111/j.1532-5415.2010.02883.x.CrossRefGoogle ScholarPubMed