Parahippocampal Atrophy is Associated with Depressive Symptoms in Alzheimer's Disease

Background Alzheimer's disease (AD) patients frequently show depressive symptoms, yet the pathological background remains unclear. The voxel-based specific regional analysis system for AD (VSRAD) allows quantification of atrophy in the medial temporal structures. We measured the degree of parahippocampal atrophy in AD patients using VSRAD, and investigated the association between imaging analysis results and the severity of depressive symptoms. Methods Brain magnetic resonance imaging (MRI) was conducted in 39 AD outpatients, and all MRI data were analyzed using VSRAD. The target region of interest (ROI) mainly consisted of the parahippocampal gyrus. The degree of atrophy in the ROI was obtained from the averaged positive z score (Z-score) of the ROT. AD patients were divided into two groups based on the severity of their depressive symptoms using the Geriatric Depression Scale (GDS), the depressive group (D group: 20 patients) and non- depressive group (ND group: 19 patients), and the clinical characteristics and VSRAD results of both groups were compared. Results There were no significant differences in demographics or cognitive function between the two groups. The Z-scores of the D group were significantly higher than those of the ND group (p<0.05). Additionally, there was a significant positive correlation between the GDS score and Z-scores in the parahippocampal gyrus. Conclusions Our findings suggested that the severity of depressive symptoms is associated with the severity of parahippocampal atrophy in AD patients.