Structural and Functional Hippocampal Changes in Subjective Cognitive Decline From the Community

et al. 2020

Preprint

Background: Previous studies reported subjective cognitive decline (SCD) linked to underlying the biomarker of early AD pathology. There is a lack of studies on whether structural brain changes and how cerebral morphology in association with verbal and visuospatial episodic memory performance.Method: We combined VBM and SBM analysis for evaluating structural alterations in gray matter atrophy and cortical thickness among individuals with SCD, MCI, AD and normal controls and investigated the associations between cerebral morphology and AVLT-H, BVMT-R performance in the whole samples and SCD, respectively. Results: No significant regional gray matter volume atrophy and cortical thickness differences were found between SCD and normal controls. We found that immediate recall in verbal learning performance was significantly correlated with the loss of bilateral hippocampus volume in SCD group, furthermore, attention capacity (SDMT) was positively correlated with bilateral hippocampus atrophy and AVLT-IR in individuals with pre-MCI cognitive status.Conclusions: Our results found hippocampal atrophy links much closer with verbal memory than visuospatial memory and immediate recall in verbal learning test was probably the primary deficit and maybe influenced by the attention capacity.

Section: Discussioncontrasting

confidence: 73%

Associations Between Cerebral Morphology and Objective Memory Performance in Patients With Subjective Cognitive Decline

Ren

et al. 2020

Preprint

“…A recent neuroimaging meta-analytic study divulged that the left hippocampus comprised the anterior emotional region (HIPe), middle cognitive region (HIPc), and posterior perceptual region (HIPp) based on its neurofunctional topography [ 12 ]. In addition, several studies have revealed that HIPsub topography is pathologically involved in preclinical AD [ 11 , 14 , 15 ]. It was also recently reported that SCD exhibited structural and functional alterations in the hippocampus [ 3 , 10 , 11 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

rTMS modulates precuneus-hippocampal subregion circuit in patients with subjective cognitive decline

et al. 2020

Aging

Hippocampal subregions (HIPsub) and their network connectivities are generally aberrant in patients with subjective cognitive decline (SCD). This study aimed to investigate whether repetitive transcranial magnetic stimulation (rTMS) could ameliorate HIPsub network connectivity by modulating one node of HIPsub network in SCD. In the first cohort, the functional connectivity (FC) of three HIPsub (i.e., hippocampal emotional, cognitive, and perceptual regions: HIPe, HIPc, and HIPp) were analyzed so as to identify alterations in HIPsub connectivity associated with SCD. Afterwards, a support vector machine (SVM) approach was applied using the alterations in order to evaluate to what extent we could distinguish SCD from healthy controls (CN). In the second cohort, a 2-week rTMS course of 5-day, once-daily, was used to activate the altered HIPsub network connectivity in a sham-controlled design. SCD subjects exhibited distinct patterns alterations of HIPsub network connectivity compared to CN in the first cohort. SVM classifier indicated that the abnormalities had a high power to discriminate SCD from CN, with 92.9% area under the receiver operating characteristic curve (AUC), 86.0% accuracy, 83.8% sensitivity and 89.1% specificity. In the second cohort, changes of HIPc connectivity with the left parahippocampal gyrus and HIPp connectivity with the left middle temporal gyrus demonstrated an amelioration of episodic memory in SCD after rTMS. In addition, SCD exhibited improved episodic memory after the rTMS course. rTMS therapy could improve the posterior hippocampus connectivity by modulating the precuneus in SCD. Simultaneous correction of the breakdown in HIPc and HIPp could ameliorate episodic memory in SCD. Thus, these findings suggested that rTMS manipulation of precuneus-hippocampal circuit might prevent disease progression by improving memory as the earliest at-risk state of Alzheimer’s disease in clinical trials and in practice.

“…Neuroimaging evidences have consistently indicated a functional heterogeneity in hippocampus subregions (HIPsub) [13][14][15]. Furthermore, several studies have indicated that HIPsub have a selective topography of pathological involvement in preclinical AD [12,15,16]. Recently, several studies have reported that SCD present the structural and functional alterations of hippocampus [3,[10][11][12]16].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, several studies have indicated that HIPsub have a selective topography of pathological involvement in preclinical AD [12,15,16]. Recently, several studies have reported that SCD present the structural and functional alterations of hippocampus [3,[10][11][12]16]. Converging evidences suggest that SCD may present differently altered patterns of HIPsub network connectivity.…”

Section: Introductionmentioning

confidence: 99%

rTMS modulates precuneus-hippocampal subregion circuit in subjective cognitive decline 

Xue

et al. 2020

Preprint

Background: To identify whether repetitive transcranial magnetic stimulation (rTMS) could ameliorate the HIPsub network connectivity by modulating one node of hippocampal subregions (HIPsub) network in subjective cognitive decline (SCD) subjects.Methods: In the first cohort, we analyzed three HIPsub (HIPe, HIPc, and HIPp) functional connectivity to identify HIPsub network connectivity alterations that relate to SCD. And we further applied a SVM approach using the alterations to identify how well this could distinguish SCD from CN. In the second cohort, rTMS with 5-day of once-daily for 2 weeks was used to modulate the altered HIPsub network connectivity in a sham-controlled design.Results: SCD subjects showed differently altered patterns of HIPsub network connectivity compared to controls. The SVM classifier showed that the abnormalities had a high power to discriminate SCD from CN, with an ACC of 86.0%, an AUC of 92.9%, 83.8% sensitivity, and 89.1% specificity. Restoration of HIPc connectivity with left parahippocampa gyrus and HIPp connectivity with left middle temporal gyrus corresponded to amelioration of episodic memory in SCD patients after 2 weeks of rTMS. Conclusion: rTMS can restore the posterior hippocampus connectivity by modulating the precuneus in SCD subjects. Correction of breakdown in HIPc and HIPp related to cognitive and perceptual processing can simultaneously ameliorate episodic memory in SCD subjects.