Magnetic Resonance Hippocampal Subfield Volumetric Analysis for Differentiating among Healthy Older Adults and Older Adults with Mild Cognitive Impairment or Major Depressive Disorder

Abstract

Objective: Depression among older adults is frequently an early symptom of cognitive decline, and is believed to be a risk factor for Alzheimer’s disease (AD). Hippocampal subfield volume loss is found in both mild cognitive impairment (MCI) and major depressive disorder (MDD). We aimed to investigate the potential of MR hippocampal subfield volumetry for discriminating among healthy older adults (HOA) and older adults with MCI or MDD. Materials and Methods: Seventy age-matched subjects (29 non-depressed MCI, 12 MDD, and 29 HOA) underwent 3-Tesla MR imaging (MRI) with high-resolution 3D-T1W-TFE whole brain. Hippocampal subfield volumetric measurements were performed using FreeSurfer software to distinguish among MCI, MDD, and HOA. Subgroup analysis with amyloid PET result was also performed. Results: Significantly smaller bilateral hippocampal tail volume was observed in MCI compared to HOA (p=0.004 and p=0.04 on the left and right side, respectively). The same comparative finding was observed at left HATA (hippocampus-amygdala-transition-area) of MCI (p=0.046). Other regions showed non-significantly smaller size in MCI than in HOA [left molecular layer HP (p=0.06), left whole hippocampus (p=0.06), and left CA1 (p=0.07)]. There was a non-significant trend toward smaller size in almost all 13 subfield hippocampal regions of MCI compared to MDD, even in subgroup analysis with amyloid PET result. Conclusion: MR hippocampal subfield volumetry may have value in routine clinical practice for screening individuals with MCI, and may be a valuable adjunct to amyloid PET study for very early-stage diagnosis of AD.