Structural and Functional Deficits in Patients with Poststroke Dementia: A Multimodal MRI Study

Abstract

Although many neuroimaging studies have reported structural and functional abnormalities in the brains of patients with cognitive impairments following stroke, little is known about the pattern of such brain reorganization in poststroke dementia (PSD). The present study was aimed at investigating alterations in spontaneous brain activity and gray matter volume (GMV) in PSD patients. We collected T1-weighted and resting-state functional magnetic resonance imaging data from 20 PSD patients, 24 poststroke nondementia (PSND) patients, and 21 well-matched normal controls (NCs). We compared the differences among the groups in GMV and the fractional amplitude of low-frequency fluctuations (fALFF). Then, we evaluated the relationship between these brain measures and cognitive assessments and explored the possible distinguisher for PSD by receiver operating characteristic (ROC) curve analysis. PSD patients showed smaller GMV in the right superior temporal gyrus and lower fALFF values in the right inferior frontal gyrus than both PSND patients and NCs, but such differences were not observed between PSND patients and NCs. Moreover, GMV in the left medial prefrontal cortex showed a significant positive correlation with the Mini-Cog assessment in PSD patients, and GMV in the left CPL displayed the highest area under the ROC curve among all the features for classifying PSD versus PSND patients. Our findings suggest that PSD patients show dementia-specific structural and functional alteration patterns, which may help elucidate the pathophysiological mechanisms underlying PSD.

Suboptimal states and frontoparietal network-centered incomplete compensation revealed by dynamic functional network connectivity in patients with post-stroke cognitive impairment

“…Functional neuroimaging has made an essential contribution to revealing the neural mechanism after stroke. Resting-state functional magnetic resonance imaging (rs-fMRI) studies have indicated that the brain’s spontaneous neural activity and functional connectivity (FC) have changed in patients with cognitive impairment after stroke ( Peng et al, 2016 ; Cai et al, 2021 ). Peng et al (2016) found a significant decrease in regional homogeneity in the bilateral anterior cingulate cortex and left posterior cingulate cortex/precuneus in PSCI patients compared to healthy volunteers and post-stroke non-cognitive impairment patients.…”

“…Functional neuroimaging has made an essential contribution to revealing the neural mechanism after stroke. Resting-state functional magnetic resonance imaging (rs-fMRI) studies have indicated that the brain's spontaneous neural activity and functional connectivity (FC) have changed in patients with cognitive impairment after stroke (Peng et al, 2016;Cai et al, 2021). Peng et al (2016) found a significant decrease in regional homogeneity in the bilateral anterior cingulate cortex and left posterior cingulate cortex/precuneus in PSCI patients compared to healthy volunteers and post-stroke non-cognitive impairment Abbreviations: PSCI, post-stroke cognitive impairment; rs-fMRI, resting-state functional magnetic resonance imaging; FC, functional connectivity; dFNC, dynamic functional network connectivity; ICA, independent component analysis; HC, healthy control; hPSCI, hemorrhagic stroke with cognitive impairment; iPSCI, ischemic stroke with cognitive impairment; MoCA, Montreal Cognitive Assessment; IC, independent component; RSN, resting-state network; SD, standard deviation; CV, coefficient of variation; AUN, the auditory network; VN, the visual network; SMN, the sensorimotor network; PON, the occipital network; PreC, the precuneus network; DMN, the default mode networks; FPN, the frontoparietal network; ECN, the executive control network; SN, the salience network; CB, the cerebellar network.…”