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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., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this article., (Copyright © 2021 Huaying Cai et al.)

Background: The hippocampus (HP) plays a critical role in memory and orientational functions and is functionally heterogeneous along the longitudinal anterior–posterior axis. Although the previous study has reported volumetric atrophy in hippocampal subfields of patients with poststroke dementia (PSD), how the functional connectivity (FC) is altered in these subfields remains unclear. Purpose: To examine the FC changes of the HP subfields in patients with PSD. Study Type: Prospective. Population: Seventeen normal controls, 20 PSD, and 24 nondemented poststroke (PSND) patients. Field Strength/Sequence: A 3.0 T/ T1‐weighted imaging, resting‐state functional and diffusion tensor imaging. Assessment: We first segmented the HP using independent component analysis, and then used granger causality analysis to calculate the directed FCs (dFCs) between the subfields and the whole brain, and compared the dFCs among PSD, PSND, and controls. Statistical Tests: Student's t‐test, chi‐square test, one‐way ANCOVA, multiple regression, support vector machine, multiple comparison correction, and reproducibility analysis. A P value < 0.05 was considered statistically significant. Results: Our results showed HP was functionally divided into HPhead, HPbody, and HPtail bilaterally along the longitudinal axis. PSD patients showed significant dementia‐specific decreases in the inward information flow and increases in the outward information flow associated with the bilateral entire HP/HPhead and left HPbody (P < 0.05). Moreover, we observed significant correlations (P < 0.05) between the cognition score and the dFCs related to the bilateral entire HP and left HPhead in the PSD group. Furthermore, dFCs of the HP and its subfields improved the classification between the PSD and PSND patients (accuracy/sensitivity/specificity: 94%/95%/93%) compared to the clinical and demographic parameters alone. Data Conclusion: These findings suggest that altered transmission and reception of information in the HP. These alternations were specific to individual subfields in PSD patients and may offer insight into the neurophysiological mechanisms underlying PSD. Evidence Level: 1 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Background: Previous studies have demonstrated that hippocampal atrophy is a hallmark of dementia and can be used to predict the outcome of post-stroke demented (PSD) patients. The hippocampus consists of several subfields but their involvement in the pathophysiology of the PSD remains unclear.Objective: The present study aimed to investigate volumetric alterations of hippocampal subfields in patients with PSD.Methods: High-resolution T1-weighted images were collected from 27 PSD and 28 post-stroke nondemented (PSND) patients who recovered from ischemic stroke, and 17 age-matched normal control (NC). We estimated the volumes of the hippocampal subfields using FreeSurfer 6.0 which segmented the hippocampus into 12 subfields in each hemisphere. The volumetric differences between the groups were evaluated by the two-sample tests after regressing out the age, sex, education, and total intracranial volume.Results: Compared with NC group, PSD group showed smaller volumes in the entire hippocampus and its subfields, and such differences were not found in PSND group. Moreover, we found the dementia-specific atrophy in the left granule cell layer of dentate gyrus (GC-DG) and CA4 in the PSD patients compared with NC and PSND. Regression analysis showed positive correlations between the changes of cognitive performance and the asymmetry index in the CA3/4 and GC-DG of the PSD group. Furthermore, we found that the volumes of hippocampal subfields provided a better classification performance than the entire hippocampus.Conclusion: Our findings suggest that the hippocampus is reduced in the PSD patients and it presents a selective subfield involvement. [ABSTRACT FROM AUTHOR]