Characterizing Early Neurovascular Changes in Mild Cognitive Impairment Using Advanced Functional MRI Mapping

Abstract

Mild Cognitive Impairment (MCI) is an intermediate period between aging and the early phases of Alzheimer disease and often contains subtle neurovascular malfunction, which is eventually associated with observable structural atrophy. Functional MRI (fMRI) especially arterial spin labeling (ASL) and blood oxygen level dependent (BOLD) imaging provides noninvasive methods to determine early neurovascular changes. This is a prospective study that examines neurovascular coupling, regional cerebral blood flow (rCBF), and changes in hemodynamic responses to the individuals with MCI through advanced fMRI mapping. Another group of 110 (60 MCI and 50 control participants) aged 55-72 years received ASL, resting-state fMRI and task-based BOLD mapping during 6 months. Findings showed that there were great decreases in rCBF in the hippocampus, posterior cingulate cortex, and precuneus of the MCI group. There were delayed and reduced functional connectivity in default mode network (DMN) nodes. Pattern recognition of fMRI signals by use of machine-learning showed that 85 percent of the samples (MCI and controls) could be classified correctly. Importantly, neuropsychological scores, namely memory and executive function scores, had a significant correlation with neurovascular changes. The paper provides insights into the importance of the state-of-the-art fMRI methodologies in the early characterization of the neurovascular dysfunction in MCI with reference to the possible application in early diagnosis, risk identification, and therapeutic assessment. These findings need to be validated by longitudinal and large-scale studies based on the integration of multimodal biomarkers to determine clinical protocols.