Background: A depressive state with Alzheimer's disease (AD) is difficult to differentiate from major depression (MD) in many cases. The purpose of this study was to identify differences between the two disorders using a battery of clinically available psychological tests.
Methods: We evaluated depression and apathy using the Geriatric Depression Scale consisting of 30 items (GDS30) and Apathy Scale in 38 patients with AD and 31 with MD who were diagnosed based on clinical symptoms and radiological findings. In addition, the Cornel Medical Index (CMI) was employed to compare the psychological features of the two disorders.
Results: In AD patients, the Apathy Scale score was greater than the GDS30 score, suggesting a strong tendency toward apathy. There was a significant difference in the GDS30/Apathy Scale score ratio between the two groups (P < 0.05, OR: 3.11). When examining the downstream mental items of the CMI, the values of tension-category parameters were significantly greater in AD patients, whereas those of depression-category parameters were significantly higher in MD patients. In individual patients, we compared the scores for the two categories, and there was a marked difference (P < 0.001, OR: 10.6).
Conclusion: These results suggest that the GDS30, Apathy Scale, and CMI are useful for differentiating MD from AD and evaluating their psychological features.