The Cingulate Island Sign is Useful for a Differential Diagnosis of Early-Onset Alzheimer's Disease and Dementia with Lewy Bodies: A 99mTc-ECD SPECT Study.

Introduction: Early-onset dementia is fast-progressing compared with late-onset dementia, with major clinical characteristics including prominent focal cerebral symptoms. Given its economic and psychological implications, proper diagnosis and treatment at an early stage is essential. In the present study, the authors conducted a retrospective study to evaluate the usefulness of various numerical indices (including CIScore calculated by eZIS, cerebral blood flow SPECT analysis software) in the differential diagnosis of early-onset dementia. Materials and Methods: This study involved patients with early-onset and mild dementia who were receiving ambulatory care at our outpatient department specializing in Alzheimer's disease (14 MCI patients, 16 AD patients, and 16 probable/possible DLB patients). ROC analysis was performed for each SVA numerical index calculated by eZIS to calculate AUC. For the AD and DLB groups, correlation between the CIScore and MMSE was assessed. Results: When SVA-A (severity) was used to differentiate AD from MCI and DLB from MCI, the respective AUC values were 0.960 and 0.911. When CIScore was used to differentiate AD from DLB (threshold value: 0.225), the obtained AUC value was 0.941, and the accuracy, sensitivity, and specificity were 90.6%, 87.5%, and 93.7%, respectively. No significant correlation was observed between the MMSE and CIScore scores in these disease groups. Conclusion: The results of this study have suggested that the SVA-A is a useful index for evaluating the conversion from MCI to either early-onset AD or DLB, and that the CIScore is useful for differentiating AD from DLB in both late-onset and early-onset dementia cases.