Structural neuroimaging of concomitant depressive symptoms in amnestic mild cognitive impairment: a pilot study

Late-life depression (LLD) and amnestic mild cognitive impairment (aMCI) can both denote prodromal Alzheimer's disease. While the two concepts share common clinical features, differential diagnosis between them is crucial. The objective of this pilot study was to explore differences in terms of the hippocampal (HC) and entorhinal cortex (EC) volume reduction between LLD and aMCI patients with (aMCI/D+ group) or without (aMCI group) depressive symptoms. Six LLD, 6 aMCI, and 6 aMCI/D+ participants were assessed using a structural magnetic resonance imaging protocol. Manual segmentation of HC and EC was carried out. The results of volumetric comparisons suggest that the HC was larger in aMCI/D+ and LLD subjects compared to aMCI participants. The left EC mean volume was slightly lower in aMCI/D+ subjects. Power analyses revealed that 36 participants per group would suffice to confirm these findings. Overall, these pilot findings suggest that aMCI can be distinguished from LLD based on cerebral atrophy measures, and that HC and EC atrophy in aMCI varies according to the presence or absence of depressive symptoms.