Abstract
Stroke causes alterations in local spontaneous neuronal activity and related networks functional connectivity. We hypothesized that these changes occur in patients with post-stroke cognitive impairment (PSCI). Fractional amplitude of low-frequency fluctuations (fALFF) was calculated in 36 patients with cognitive impairment, including 16 patients with hemorrhagic stroke (hPSCI group), 20 patients with ischemic stroke (iPSCI group). Twenty healthy volunteers closely matched to the patient groups with respect to age and gender were selected as the healthy control group (HC group). Regions with significant alteration were regarded as regions of interest (ROIs) using the one-way analysis of variance, and then the seed-based functional connectivity (FC) with other regions in the brain was analyzed. Pearson correlation analyses were performed to investigate the correlation between functional indexes and cognitive performance in patients with PSCI. Our results showed that fALFF values of bilateral posterior cingulate cortex (PCC)/precuneus and bilateral anterior cingulate cortex in the hPSCI group were lower than those in the HC group. Compared with the HC group, fALFF values were lower in the superior frontal gyrus and basal ganglia in the iPSCI group. Correlation analysis showed that the fALFF value of left PCC was positively correlated with MMSE scores and MoCA scores in hPSCI. Besides, the reduction of seed-based FC values was reported, especially in regions of the default-mode network (DMN) and the salience network (SN). Abnormalities of spontaneous brain activity and functional connectivity are observed in PSCI patients. The decreased fALFF and FC values in DMN of patients with hemorrhagic and SN of patients with ischemic stroke may be the pathological mechanism of cognitive impairment. Besides, we showed how to use fALFF values and functional connectivity maps to specify a target map on the cortical surface for repetitive transcranial magnetic stimulation (rTMS).
Highlights
Post-stroke cognitive impairment (PSCI) is a common functional disorder after stroke, including executive dysfunction, attention disorders, memory impairment, language disorders, and visual space impairment (Iadecola et al, 2019)
Significant differences in Fractional amplitude of low-frequency fluctuations (fALFF) values were found between the stroke and healthy control (HC) groups, but not between the hemorrhagic stroke with cognitive impairment (hPSCI) and ischemic stroke with cognitive impairment (iPSCI) groups
Compared with the HC group, fALFF values in the iPSCI group were lower in the left caudate, left putamen, right dorsolateral superior frontal gyrus, and right medial superior frontal gyrus
Summary
Post-stroke cognitive impairment (PSCI) is a common functional disorder after stroke, including executive dysfunction, attention disorders, memory impairment, language disorders, and visual space impairment (Iadecola et al, 2019). Most previous studies used independent component analysis (ICA), which explores the changes of the independent brain spontaneous activity to interpret the rs-fMRI signals (De Luca et al, 2006). Ding et al used the ICA analysis to identify the DMN and found significantly decreased FC in the PCC/precuneus in patients with or without cognitive impairment after stroke, but FC in the mPFC increased (Ding et al, 2014). Jiang et al found decreased FC in the right mPFC and precuneus in patients with acute brainstem stroke by ICA (Jiang et al, 2018) This result was in accordance with Chen’s, which provided a new idea for the neural mechanism of cognitive impairment after an ischemic brainstem stroke (Chen et al, 2019)
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