Intra-network and inter-network shared connectivity patterns in patients with remitted late-life depression and amnestic mild cognitive impairment

Abstract

Objectives Both remitted late-life depression (rLLD) and amnestic mild cognitive impairment (aMCI) alter brain function in individual regions. They are also disconnection syndromes associated with a high-risk of developing Alzheimer's disease (AD). Resting-state functional connectivity magnetic resonance imaging (rs-fcMRI) was performed to define the shared and distinct aberrant patterns in intra-network and inter-network connectivity between rLLD and aMCI. Methods We investigated rs-fcMRI in five functionally well-defined brain networks in 55 rLLD, 87 aMCI, and 114 healthy controls (HC). Results Compared with HC, rLLD showed a reduced degree of functional connectivity in the bilateral inferior temporal cortex and supplemental motor area, and reduced correlations within the sensory-motor network (SMN) and in the default-mode network (DMN) – control network (CON) pair. aMCI showed only focal functional changes in regions of interest pairs, a trend toward increased correlations within the salience network and SMN, and a trend toward reduced correlation in the DMN-CON pair. Furthermore, rLLD exhibited more severely altered functional connectivity compared to aMCI. Interestingly, these altered connectivities were associated with specific multi-domain cognitive and behavioral functions in both rLLD and aMCI. Notably, altered connectivity between right middle temporal cortex and posterior cerebellum was negatively correlated with Mattis Dementia Rating Scale scores in both rLLD and aMCI. Conclusions These results demonstrate that rLLD and aMCI may share convergent and divergent aberrant intra-network and inter-network connectivity patterns. It further suggests that dysfunction in right specific temporal-cerebellum neural circuit may contribute to the similarities observed rLLD and aMCI conversion to AD.