Functional connectivity and mild behavioral impairment in dementia-free elderly

Area of Science:

• Neuroscience
• Gerontology
• Radiology

Background:

• Mild behavioral impairment (MBI) is a syndrome of emergent neuropsychiatric symptoms in later life.
• MBI identifies individuals at high risk for dementia and is associated with early neurodegenerative markers.
• Functional connectivity (FC) alterations in MBI are not well understood but may offer insights into early disease mechanisms.

Purpose of the Study:

• To investigate the hypothesis that individuals with MBI exhibit reduced FC within the default mode network (DMN) and salience network (SN).
• To compare FC patterns in individuals with MBI (MBI+) versus those without MBI (MBI-) using resting-state functional magnetic resonance imaging (rs-fMRI).

Main Methods:

• rs-fMRI data were analyzed from 95 dementia-free participants (32 MBI+, 63 MBI-) from two cohort studies.
• Seed-based connectivity analysis focused on the posterior cingulate cortex (PCC) within the DMN and anterior cingulate cortex (ACC) within the SN.
• Statistical analyses controlled for age, sex, education, and cognitive scores, using FDR correction for multiple comparisons.

Main Results:

• MBI+ individuals showed significantly reduced FC between the PCC and medial prefrontal cortex within the DMN.
• MBI+ individuals exhibited reduced FC between the ACC and the left anterior insula within the SN.
• These FC reductions were observed in dementia-free older adults with MBI.

Conclusions:

• MBI in dementia-free older adults is associated with reduced FC in brain networks typically disrupted in dementia.
• The observed FC changes in MBI+ individuals align with patterns seen in early-stage Alzheimer's disease.
• MBI may serve as an early indicator for individuals experiencing neurodegenerative processes.