Resting-state fMRI markers of conversion to dementia in amnestic MCI: a pilot study

Abstract

Introduction Patients with amnestic mild cognitive impairment (aMCI) have a high risk of transition to Alzheimer’s disease. Analysis of potential biomarkers of conversion to dementia in this clinical group is crucial for prognosis and early intervention. Objectives The aim of the pilot study was to compare whole-brain functioning characteristics (fMRI, spontaneous activity and local coherence) in aMCI converters and non-converters to dementia. Methods Nine aMCI converters to dementia of the Alzheimer’s type (mean age 69.2 ± 8.2; 9 females) and ten aMCI non-converters (mean age 65.9 ± 6.1; 8 females) underwent resting-state fMRI (3T). All patients were followed up for three years. Baseline whole-brain amplitude of low-frequency fluctuations (ALFF) and local coherence (LCOR) were compared between groups (CONN-fMRI toolbox 19.с, https://web.conn-toolbox.org/; p < .001 voxelwise, p(FDR) < .05 clusterwise). Age was included in the analyses as a second-level covariate. Results As compared to non-converters, aMCI converters were characterized by higher ALFF and LCOR values in the cluster located in the frontal medial cortex and frontal pole bilaterally. Conclusions Frontal medial cortex and frontal pole are involved in a wide range of cognitive functions, including episodic memory and “hot” (motivational) executive control (Rolls. ProgNeurobiol 2022; 217; Friedman, Robbins. Neuropsychopharmacology 2022; 47(1) 72-89). Both increased and decreased LCOR/ALFF values in aMCI converters compared to non-converters were found, although in the other regions (Mondragón et al. Dement Geriatr Cogn Dis Extra 2021; 11(3) 235–249; Khatri, Kwon. Front Aging Neurosci. 2022; 14). It seems reasonable to clarify if the brain functional features revealed in our study are the markers of conversion to dementia in aMCI. Disclosure of Interest None Declared