Neural Correlates of Mild Behavioral Impairment: A Functional Brain Connectivity Study Using Resting-State Functional Magnetic Resonance Imaging

Abstract

Background: Mild behavioral impairment (MBI) is associated with accelerated cognitive decline and greater risk of dementia. However, the neural correlates of MBI have not been completely elucidated. Objective: The study aimed to investigate the correlation between cognitively normal participants and participants with amnestic mild cognitive impairment (aMCI) using resting-state functional magnetic resonance imaging. Methods: The study included 30 cognitively normal participants and 13 participants with aMCI (20 men and 23 women; mean age, 76.9 years). The MBI was assessed using the MBI checklist (MBI-C). Region of interest (ROI)-to-ROI analysis was performed to examine the correlation between MBI-C scores and functional connectivity (FC) of the default mode network, salience network, and frontoparietal control network (FPCN). Age, Mini-Mental State Examination score, sex, and education were used as covariates. A p-value of 0.05, with false discovery rate correction, was considered significant. Results: A negative correlation was observed between the MBI-C total score and FC of the left posterior parietal cortex with the right middle frontal gyrus. A similar result was obtained for the MBI-C affective dysregulation domain score. Conclusion: FPCN dysfunction was detected as a neural correlate of MBI, especially in the affective dysregulation domain. This dysfunction may be associated with cognitive impairment in MBI and conversion of MBI to dementia; however, further longitudinal data are needed to examine this relationship.

Neuroimaging of mild behavioral impairment: A systematic review

“…Three studies also included patients with AD 39,45,48 . MBI was assessed using the MBI‐Checklist 52 in most studies 14,17,36,38,40,41,43–49,51 . Three studies used MBI criteria 2,11,12 .…”

“…The brain regions (hippocampus, parahippocampal gyrus, entorhinal cortex, and temporal lobe) identified as neural correlates of MBI 13,36,[39][40][41]43,44 (Figure 2) are known to show atrophy in the early stage of AD. 54 Tau burden in the entorhinal cortex and hippocampus has been linked to MBI in amyloid-positive NC, 17 but not in NC with an unknown amyloid status.…”

“…Alternatively, WMH might be involved in MBI via brain atrophy. 47 Functional imaging 38,40,49,51 has suggested dysfunction in the DMN, FPCN, and SAN as neural correlates of MBI (Figure 3).…”

“…14,17,36,44,48,51 Second, various participants and assessments of MBI were used. Third, many studies were crosssectional, 13,14,17,36,[38][39][40][41][42][43][44][45][46][47][49][50][51] and the relationship between neural correlates of MBI and conversion from MBI to dementia was not completely clear. Fourth, statistical analysis was not possible because the study methods varied.…”

Functional connectivity and mild behavioral impairment in dementia‐free elderly

“… 20 The only rs‐fMRI study of MBI in participants with NC and amnestic MCI reported no MBI‐associated FC changes within the DMN and SN but identified an association between MBI and dysfunction within the fronto‐parietal control network. 21 This study used a self‐report of MBI symptoms with infrequent endorsement of clinically significant MBI. Here, we aimed to investigate FC alterations in the DMN and SN in dementia‐free older adults with MBI compared to those without, using an informant‐rated MBI assessment.…”