Apathy and intrinsic functional connectivity networks in amnestic mild cognitive impairment

Abstract

BackgroundAlthough several prior works reported that apathy is associated with conversion to Alzheimer’s disease in individuals with amnestic mild cognitive impairment (aMCI), effects of apathy on the functional connectivity (FC) of the brain remain unclear. In this study, we assessed the pattern of association between apathy and default mode network (DMN), salience network and central executive network (CEN) in aMCI subjects.MethodsFifty subjects with aMCI and 50 controls (CONs) participated in this study. They underwent clinical assessments and magnetic resonance imaging for the structural and resting-state scan. We explored the patterns of association between apathy inventory (IA) total score and the whole-brain voxel-wise FCs of the DMN, salience network and CEN in aMCI subjects.ResultsWe observed that the FCs of the DMN were less and those of CEN were more in the aMCI group than the CON group. Total IA score was negatively correlated with FCs of the anterior cingulate within the DMN, and positively correlated with FCs of the middle frontal, inferior frontal, and supramarginal gyrus within the CEN in the aMCI group.ConclusionOur findings suggest that distinctive patterns of association between apathy and FCs in the DMN and CEN in the aMCI group might reflect the putative role of functional network change in the development of apathy in aMCI.

Altered frontal and insular functional connectivity as pivotal mechanisms for apathy in Alzheimer's disease

“…A third study investigating a sample of 50 MCI patients with an amnestic presentation was conducted with a seed-based methodology to investigate the main large-scale networks. In this study apathy was associated with increased functional connectivity between the middle frontal gyrus (chosen as seed region for the computation of the executive-control network) and a series of frontal and inferior parietal regions (Joo et al, 2016), supporting the idea of apathy emerging in concomitance with increased connectivity of the DLPFC. Together with these three studies, our findings contribute to lay out the principle that apathy can be the result of disrupted connectivity among regions.…”

“…A few studies of apathy in AD have investigated large-scale networks that support certain cognitive statuses such as the default mode network or the attentional networks (Balthazar et al, 2014;Joo et al, 2016;Munro et al, 2015). This study of apathy in patients with clinically-established AD was based on testing the relevance of disruption of specific maps of connectivity informed by theoretical frameworks proposed in previous studies.…”

“…Task-free functional MRI (TFfMRI) allows the measurement of resting brain synchronized activity through the analysis of low frequency oscillations in the blood oxygen level dependent signal, and allows the testing of sets of predefined regions selected as "seeds". A number of studies have investigated functional connectivity of large-scale networks such as the default-mode network and attentional networks (Balthazar et al, 2014;Joo, Lee, & Lim, 2016;Munro et al, 2015). This study, however, is the first to have used TFfMRI to test apathy as a symptom linked to failure of selected theory-informed functional maps of connections in a sample of patients with mild AD.…”

Multimodal brain imaging connectivity analyses of emotional and motivational deficits in depression among women

“…For each participant, we created the seed masks using a 5 mm radius sphere (3 mm for the amygdala) around the coordinates of the participant-specific local maximums found (1) within the corresponding ROI of each contrast and (2) within 15 mm (10 mm for the amygdala) of the maximums of the healthy controls. 7,[22][23][24][25] This approach accounted for interindividual variability and is thought to be the most sensitive. 37 Within each seed region, we calculated the physiologic variable by deconvolving and mean-correcting the first eigenvariate of the high-pass-filtered (128 s) BOLD signal after regressing out motion parameters.…”

“…Indeed, the dlPFC, ACC and amygdala are the 3 main structures engaged in apathy. Based on findings from the early stages of degenerative disorders that showed enhanced functional connectivity between frontal areas associated with apathy, 22,23 we expected to find enhanced functional connectivity between the dlPFC and the ACC.…”