Cut-Off Values For EEG Frequency in Differentiation of Alzheimer, Non-Alzheimer Dementia and Healthy Subjects: An Application of 3D-ROC Surface Method Alzheimer Demansı, Diğer Tip Demanslılar ve Sağlıklı Bireylerin Ayrımında EEG Frekansı İçin Cut-Off Değerleri: 3D-ROC Yüzeyi Metodunun Bir Uygulaması

Objectives: To write a new macro programme for the use of the non-parametric 3-D Receiver Operating Characteristic (ROC) surface method in the discrimination of three or more groups, to study the usefulness of electroencephalography (EEG) frequency in the diagnosis of Alzheimer type dementia (AD), non-Alzheimer type dementia (NAD) and healthy subjects, and to determine cut-off values of EEG frequency. Patients and Methods: The mean EEG frequencies in the left fontal region EEG records of subjects in the present study were calculated and the ROC surface method was used in discrimination of the groups. Results: The volume under the ROC surface was calculated as 0.464±0.150. Accuracy of the mean frequency in differentiation of groups was statistically significant (p=0.024). 8 Hz was found to be convenient for differentiation of AD from NAD patients and 10 Hz for the differentiation of NAD patients and healthy subjects. The sensitivity was 87.5% for Alzheimer’s dementia diagnosis and total accuracy was 65% using this cut-off pair. Conclusion: We suggest that the mean EEG frequency may be used only as a pre-diagnostic tool for the differential diagnosis of these groups.