Functional brain activity in patients with amnestic mild cognitive impairment: an rs-fMRI study

Abnormalities of regional brain activity in patients with asymptomatic internal carotid artery occlusion: a resting-state fMRI study

BACKGROUND

Asymptomatic internal carotid artery occlusion (aICAO) disrupts cerebral blood flow and can impair brain function. While previous research has primarily focused on abnormal functional connectivity between brain networks or regions in aICAO patients, less is known about specific regional brain activity alterations. This study investigated changes in local brain activity and their associations with cognitive function in patients with aICAO.

METHODS

A total of 26 unilateral patients with aICAO without MRI lesions and 25 matched healthy controls (HCs) underwent resting-state functional magnetic resonance imaging and neuropsychological assessment. Local brain activity in patients with aICAO was investigated using percentage amplitude of fluctuation (PerAF) and degree centrality (DC). The association between the abnormal regional brain activity in patients with aICAO and cognitive function was also explored.

RESULTS

Compared with HCs, patients with aICAO showed decreased PerAF in the ipsilateral (occlusion side, right) superior temporal gyrus (temporal pole), ipsilateral inferior frontal gyrus (triangular part). In addition, decreased DC was detected in the ipsilateral cuneus of patients with aICAO, while increased DC was observed in the contralateral (opposite to occlusion side, left) precuneus and contralateral inferior frontal gyrus (triangular part) among patients with aICAO. Furthermore, the DC value of contralateral precuneus in aICAO group was negatively correlated with Montreal Cognitive Assessment (MoCA) (r = -0.612, p = 0.002), Forward Digit Span Test (FDST) (r = -0.677, p = 0.001), and Backward Digit Span Test (BDST) (r = -0.531, p = 0.011) scores.

CONCLUSIONS

Our findings revealed abnormal local spontaneous brain activity within brain regions associated with cognitive functions in patients with unilateral aICAO. Notably, some of these abnormalities correlated with their cognitive impairments. This study contributes to the understanding of potential neural mechanisms underlying cognitive dysfunction in unilateral aICAO patients.

The effectiveness and safety of acupuncture for the treatment of cognitive impairment from Parkinson disease: A meta-analysis and systematic review

BACKGROUND

This systematic review and meta-analysis examined the efficacy and safety of acupuncture for treating patients with cognitive impairment from Parkinson disease (PDCI).

METHODS

We searched the China National Knowledge Infrastructure, Wanfang (WF), Weipu (VIP), China Biology Medicine, PubMed, Embase, Cochrane Library, Web of Science and Clinical Trials electronic databases from database inception to January 2024 to identify randomized controlled trials that examined the use of acupuncture to treat PDCI. Studies published in Chinese or English were considered eligible. Two independent reviewers performed the literature search. Data extracted from the included studies were analyzed via RevMan 5.4 software for Meta. The mean effect sizes and 95% confidence intervals were calculated.

RESULTS

This meta-analysis ultimately included 9 articles involving a total of 629 patients. The outcome measures included the mini-mental state examination, the montreal cognitive assessment (MoCA), and the overall effective rate. The meta-analysis revealed that there were significant differences in all 3 outcomes between the experimental and control groups.

CONCLUSIONS

Acupuncture can be used as an effective treatment for PDCI and is significantly superior to conventional treatments. However, considering the low methodological quality of the included studies, results of this meta-analysis should be interpreted with caution. In addition, due to the inconsistency observed in this study, more clinical trials are needed for further investigation.

Multimodal magnetic resonance imaging analysis of early mild cognitive impairment

BackgroundEarly mild cognitive impairment (EMCI) represents a prodromal stage of dementia, and early detection is crucial for delaying dementia progression. However, accurately identifying its neuroimaging features remains challenging.ObjectiveTo comprehensively evaluate structural and functional neuroimaging changes in EMCI using multimodal magnetic resonance imaging (MRI) techniques.MethodsOne hundred and eleven participants were included from the Alzheimer's Disease Neuroimaging Initiative (ADNI): 36 with cognitively normal (CN), 30 with EMCI, 32 with late mild cognitive impairment (LMCI), and 13 with Alzheimer's disease (AD). FreeSurfer software was employed to segment hippocampal and amygdala subregions. The amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), regional homogeneity (ReHo), and functional connectivity were processed using Data Processing & Analysis for Brain Imaging toolbox. Graph Theoretical Network Analysis toolbox was utilized to evaluate global functional network.ResultsThe volume of most hippocampal and amygdala subregions was decreased in AD group than those of EMCI group in structural MRI. Significant differences were found between EMCI and AD group in fALFF (right insula) and ReHo (bilateral caudate regions). EMCI group exhibited stronger functional connectivity between left hippocampus and right inferior temporal gyrus (compared to CN), left inferior temporal gyrus (compared to LMCI), and cerebellum crus 8 (compared to AD). EMCI group exhibited stronger connectivity between right hippocampus and left anterior cingulate gyrus compared to AD. Network metrics showed no significant differences among these groups, but all exhibited small-world properties.ConclusionsMultimodal MRI analysis revealed the neuroimaging characteristics of EMCI and promoted the understanding of the mechanisms underlying neuroimaging changes in EMCI.

Discovery of the microbiota-gut-brain axis mechanisms of acupuncture for amnestic mild cognitive impairment based on multi-omics analyses: A pilot study

OBJECTIVES

Acupuncture is a promising therapy for amnestic mild cognitive impairment (aMCI). Growing evidence suggest that alterations in the microbiota-gut-brain (MGB) axis contribute to the development and progression of aMCI. However, little is known about whether and how acupuncture change the MGB axis of aMCI individuals.

METHODS

This was a randomized, controlled, clinical trial. Forty patients with aMCI were randomly allocated to either the acupuncture group or the waitlist group. The primary outcome was the change in the Alzheimer's Disease Assessment Scale-Cognitive Scale (ADAS-Cog) score. In addition, multi-omics was performed to detect changes in brain function, gut microbiota, and serum metabolites. Generalized estimating equations were used to estimate the outcomes, and correlational analyses were performed to explore the relationships between the clinical and multi-omics data.

RESULTS

Compared to a mean baseline to week 12 change of -3.94 in the acupuncture group, the mean change in the waitlist group was 1.72 (net difference, -5.66 [95 % CI, -6.98 to -4.35]). Compared to the waitlist group, acupuncture's MGB axis modulatory effect exhibited altered the regional homogeneity values of Frontal_Med_Orb_L, Cingulum_Mid_L, and Frontal_Sup_Medial_L, relative abundance of gut Ruminococcus_sp_AF43_11 and s_Eubacterium_coprostanoligenes, and levels of serum (11E,15Z)-9,10,13-trihydroxyoctadeca-11,15-dienoic acid, dipropylene glycol dimethyl ether, N6-Me-dA, and DPK, which correlated with changes in ADAS-Cog scores.

CONCLUSIONS

Our data imply that acupuncture ameliorates overall cognitive function, along with changes in brain activity, gut microbiota, and serum metabolites, providing preliminary evidence of the mechanisms acting through the MGB axis underlying the effects of acupuncture on aMCI.

Reduced Functional Connectivity in Nucleus Accumbens Subregions Associates With Cognitive Changes in Alzheimer's Disease

BACKGROUND AND PURPOSE

The nucleus accumbens (NAc), an important component of the reward circuit, is believed to play an indispensable role in Alzheimer's disease (AD). This study aimed to explore alterations in the functional connectivity (FC) of NAc subregions in AD patients and to explore their associations with neuropsychological profiles.

METHODS

Total 45 AD patients and 41 healthy controls (HCs) were recruited for this study. Four subregions of the NAc were used as regions of interest for whole-brain FC analysis. Correlation analyses were conducted to explore the relationships between the changed FC of brain regions with significant differences and neuropsychological profiles.

RESULTS

Compared with HCs, decreased FC was observed between NAc subregions and regions of the orbitofrontal cortex (OFC), precuneus (PCUN), insula (INS), cerebellum 8, and putamen in AD patients (Gaussian random field [GRF] corrected, voxel-level p < 0.001, cluster-level p < 0.05). Furthermore, the FC between the left core and left PCUN was correlated with the score of the auditory verbal learning test immediate recall task in AD patients (r = 0.441, p = 0.003, Bonferroni corrected).

CONCLUSION

Disruptions in connectivity between the NAc subregions and important cognitive-related areas may be related to the cognitive deficits observed in AD patients, especially episodic memory function.

Nebulized seabuckthorn seed oil inhalation attenuates Alzheimer's disease progression in APP/PS1 mice

Seabuckthorn (Hippophae rhamnoides L.) is known for its medicinal properties in treating various diseases, including neurological conditions. However, the therapeutic effect of inhaled seabuckthorn seed oil (SSO) on Alzheimer's disease (AD) remains not fully understood. This study explores the effects of nebulized inhalation of SSO in 9-month-old APP/PS1 mice over 21 days. The results showed that nebulized SSO improved memory and cognition. Using 7.0T MRI to monitor blood oxygenation level dependent (BOLD) signals revealed that SSO altered the Amplitude of Low Frequency Fluctuations (ALFF) and Regional Homogeneity (ReHo) signaling such as in the amygdala and substantia innominate, and hippocampus. Enzyme-linked immuno sorbent assay (ELISA) and pathological analyses indicated reduced neuroinflammation in plasma and brain, decreased neuronal necrosis, lower β-amyloid (Aβ) protein levels, reduced amyloid deposition, and increased tyrosine hydroxylase activity. Additionally, SSO promoted gut microbiota remodeling by increasing alpha diversity and boosting levels of probiotics such as Verrucomicrobia, Bifidobacterium, Prevotella, and Akkermansia, without adverse effects on lung tissue. Nebulized inhalation of SSO may slow AD progression by modulating inflammation and amyloid deposition. Nebulized inhalation offered a potential method for enhancing drug delivery across the blood-brain barrier with reduced systemic side effects.

Multiparameter resting-state functional magnetic resonance imaging as an indicator of neuropsychological changes in Binswanger's disease with mild cognitive impairment

The underlying neuropathological mechanisms in Binswanger's disease (BD) with mild cognitive impairment (BD-MCI) remain unclear. The multiparameter functional magnetic resonance imaging (fMRI) including amplitude of low-frequency fluctuations (ALFF), fractional amplitude of low-frequency fluctuations (fALFF), regional homogeneity (ReHo), independent component analysis (ICA), and edge-link analysis was utilized to explore the abnormal brain networks of BD-MCI patients. Compared with the BD without MCI group, this study revealed that the ALFF values in the BD-MCI group were significantly increased in the Temporal_Inf_R, Frontal_Mid_Orb_L, and Hippocampus_L, while decreased in the SupraMarginal_R and Precuneus_R. The fALFF value in the BD-MCI group exhibited a reduction in the Frontal_Med_Orb_L. Additionally, ReHo values in the BD-MCI group increased in the Hippocampus_R but decreased in several areas including Precentral_L, Putamen_L, Postcentral_R, Supp_Motor_Area_R, and SupraMarginal_L. The results of ICA revealed that patients diagnosed with BD-MCI exhibited abnormal connectivity patterns across 12 groups of independent components and 5 distinct groups of brain networks. In one group, the internal connectivity within the brain network exhibited abnormalities. The correlation analysis between ALFF and ReHo values and clinical scales revealed a significant negative correlation between the bilateral hippocampus and Mini-Mental State Examination (MMSE) scores. Conversely, ReHo values for Postcentral_R and SupraMarginal_L were significantly positively correlated with MMSE scores. In summary, the results of our study suggest that patients diagnosed with BD-MCI display atypical activity across several brain regions. The observed changes in these areas encompass a range of functional networks. The reduced coordination among these functional networks may play a role in the deterioration of cognitive functions and decision-making capabilities, potentially serving as a critical mechanism contributing to the early manifestation of cognitive impairments.

The Correlations between Volume Loss of Temporal and Subcortical Functional Subregions and Cognitive Impairment at Various Stages of Cognitive Decline

BACKGROUND

The relationship between subregion atrophy in the entire temporal lobe and subcortical nuclei and cognitive decline at various stages of Alzheimer's disease (AD) is unclear.

METHODS

We selected 711 participants from the AD Neuroimaging Initiative (ADNI) database, which included 195 cases of cognitively normal (CN), 271 cases of early Mild cognitive impairment (MCI) (EMCI), 132 cases of late MCI (LMCI), and 113 cases of AD. we looked at how subregion atrophy in the temporal lobe and subcortical nuclei correlated with cognition at different stages of AD. The volume of the subregions was measured from the human Brainnetome atlas (BNA-246) using voxel-based morphometry and discriminant and correlation analyses were performed.

RESULTS

Only the left premotor thalamus demonstrated significant shrinkage in individuals with EMCI (p = 0.012). Discriminant analysis revealed that the left rostral Brodmann area 20 has the highest discriminatory ability among all temporal subregions to distinguish patients with AD from CN. While the left caudal hippocampus can efficiently distinguish patients with LMCI from EMCI. While the right rostral Brodmann area 20 was the most effective in distinguishing AD from LMCI. Correlation analysis revealed that the left nucleus accumbens, left caudal area 35/36, and left sensory thalamus had a mild correlation with cognitive scores measured using the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-cog) 13 and Mini-Mental State Examination (MMSE) scores.

CONCLUSIONS

Our findings show that the right rostral area 20 in the inferior temporal gyrus plays a significant role in cognitive impairment in AD.

Exercise intervention on the brain structure and function of patients with mild cognitive impairment: systematic review based on magnetic resonance imaging studies

Objective

This systematic review evaluates the impact of exercise intervention in MCI patients and discusses the potential neural mechanisms.

Methods

A systematic search and screening of relevant literature was conducted in English and Chinese databases. Based on predefined keywords and criteria, 24 articles were assessed and analyzed.

Results

Structurally, a significant increase was observed in the hippocampal and gray matter volumes of MCI patients following exercise intervention, with a trend of improvement in cortical thickness and white matter integrity. Functionally, after the exercise intervention, there were significant changes in the local spontaneous brain activity levels, cerebral blood flow, and functional connectivity during rest and memory encoding and retrieval tasks in MCI patients.

Conclusion

Exercise may contribute to delaying neurodegenerative changes in brain structure and function in patients with MCI. However, the underlying neural mechanisms require further research.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023482419.

Abnormal postcentral gyrus voxel-mirrored homotopic connectivity as a biomarker of mild cognitive impairment: A resting-state fMRI and support vector machine analysis

BACKGROUND

While patients affected by mild cognitive impairment (MCI) exhibit characteristic voxel-mirrored homotopic connectivity (VMHC) alterations, the ability of such VMHC abnormalities to predict the diagnosis of MCI in these patients remains uncertain. As such, this study was performed to evaluate the potential role of VMHC abnormalities in the diagnosis of MCI.

METHODS

MCI patients and healthy controls (HCs) were enrolled and subjected to resting-state functional magnetic resonance imaging (rs-fMRI) and neuropsychological testing. VMHC and support vector machine (SVM) techniques were then used to examine the collected imaging data.

RESULTS

Totally, 53 MCI patients and 68 healthy controls were recruited. Compared to HCs, MCI patients presented with an increase in postcentral gyrus VMHC. SVM classification demonstrated the ability of postcentral gyrus VMHC values to classify HCs and MCI patients with accuracy, sensitivity, and specificity values of 63.64 %, 71.69 %, and 89.71 %, respectively.

CONCLUSION

VMHC abnormalities in the postcentral gyrus may be mechanistically involved in the pathophysiological progression of MCI patients, and these abnormal VMHC patterns may also offer utility as a neuroimaging biomarker for MCI patient diagnosis.

Local functional connectivity abnormalities in mild cognitive impairment and Alzheimer's disease: A meta-analytic investigation using minimum Bayes factor activation likelihood estimation

Functional magnetic resonance imaging research employing regional homogeneity (ReHo) analysis has uncovered aberrant local brain connectivity in individuals with mild cognitive impairment (MCI) and Alzheimer's disease (AD) in comparison with healthy controls. However, the precise localization, extent, and possible overlap of these aberrations are still not fully understood. To bridge this gap, we applied a novel meta-analytic and Bayesian method (minimum Bayes Factor Activation Likelihood Estimation, mBF-ALE) for a systematic exploration of local functional connectivity alterations in MCI and AD brains. We extracted ReHo data via a standardized MEDLINE database search, which included 35 peer-reviewed experiments, 1,256 individuals with AD or MCI, 1,118 healthy controls, and 205 x-y-z coordinates of ReHo variation. We then separated the data into two distinct datasets: one for MCI and the other for AD. Two mBF-ALE analyses were conducted, thresholded at "very strong evidence" (mBF ≥ 150), with a minimum cluster size of 200 mm³. We also assessed the spatial consistency and sensitivity of our Bayesian results using the canonical version of the ALE algorithm. For MCI, we observed two clusters of ReHo decrease and one of ReHo increase. Decreased local connectivity was notable in the left precuneus (Brodmann area - BA 7) and left inferior temporal gyrus (BA 20), while increased connectivity was evident in the right parahippocampal gyrus (BA 36). The canonical ALE confirmed these locations, except for the inferior temporal gyrus. In AD, one cluster each of ReHo decrease and increase were found, with decreased connectivity in the right posterior cingulate cortex (BA 30 extending to BA 23) and increased connectivity in the left posterior cingulate cortex (BA 31). These locations were confirmed by the canonical ALE. The identification of these distinct functional connectivity patterns sheds new light on the complex pathophysiology of MCI and AD, offering promising directions for future neuroimaging-based interventions. Additionally, the use of a Bayesian framework for statistical thresholding enhances the robustness of neuroimaging meta-analyses, broadening its applicability to small datasets.

Episodic memory network characteristics in patients with amnestic mild cognitive impairment accompanied by executive function impairment

OBJECTIVE

To explore the functional connectivity (FC) characteristics of the episodic memory network (EMN) in amnestic mild cognitive impairment (aMCI) patients with different levels of executive function (EF).

METHODS

This study included 76 participants from the Alzheimer's Disease Neuroimaging Initiative database, comprising 23 healthy controls (HCs) and 53 aMCI patients. Based on EF levels, aMCI patients were categorized into aMCI-highEF and aMCI-lowEF groups. Cognitive function scores, pathological markers (cerebrospinal fluid β-amyloid, total tau protein, phosphorylated tau protein, AV45-PET, and FDG-PET), and functional magnetic resonance imaging were collected and compared among the three groups. Seed-based FC analysis was used to examine differences in the EMN among the groups, and partial correlation analysis was employed to investigate the relationship between changes in FC and cognitive function scores as well as pathological markers.

RESULTS

Compared to the aMCI-highEF group, the aMCI-lowEF group exhibited more severe cognitive impairment, decreased cerebral glucose metabolism, and elevated AV45 levels. Significant FC differences in the left superior temporal gyrus (STG) of the EMN were observed among the three groups. Post hoc analysis revealed that the aMCI-lowEF group had increased FC in the left STG compared to the HCs and aMCI-highEF groups, with statistically significant differences. Correlation analysis showed a significant negative correlation between the differences in FC in the left STG of aMCI-highEF and aMCI-lowEF groups and Rey Auditory Verbal Learning Test forgetting scores. Receiver operator characteristic curve analysis indicated an area under the curve of 0.741 for distinguishing between aMCI-highEF and aMCI-lowEF groups based on FC of left STG, with a sensitivity of 0.808 and a specificity of 0.667.

CONCLUSION

aMCI-lowEF exhibits characteristic changes in FC within the EMN, providing theoretical support for the role of EF in mediating EMN alterations and, consequently, impacting episodic memory function.

Evaluating the efficacy and safety of Alzheimer's disease drugs: A meta-analysis and systematic review

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disorder. Dementia severity was assessed mainly through cognitive function, psychobehavioral symptoms, and daily living ability. Currently, there are not many drugs that can be selected to treat mild to moderate AD, and the value of drugs remains controversial.

OBJECTIVE

The aim of this study is to quantitatively evaluate the efficacy and safety of cholinesterase inhibitors (ChEIs), memantine, and sodium oligomannate (GV-971) in the treatment of patients with AD. Additionally, molecular docking analysis will be used to investigate the binding affinities of donepezil, galantamine, rivastigmine, and memantine with key receptor proteins associated with AD, including beta-amyloid (Abeta), microtubule-associated protein (MAP), apolipoprotein E4 (APOE4), and Mitofusin-2 (MFN2), to further validate the results of the meta-analysis.

METHODS

We obtained clinical trials characterized by randomization, placebo control, and double-blinded methodologies concerning ChEIs, memantine, and GV-971. Statistical analysis was performed using Review Manager Version 5.4 software. Molecular docking was also conducted to evaluate the results.

RESULTS

All drugs improved the cognitive function, with the effect value ranging from -1.23 (95% CI -2.17 to -0.30) for 20 mg memantine to -3.29 (95% CI -4.14 to -2.45) for 32 mg galantamine. Although 32 mg galanthamine and GV-971 did not improve the clinicians' Global Impression of Change scale, other drugs showed significant results compared with placebo. On NPI, only 10 mg of donepezil and 24 mg of galantamine had improvement effects. On ADCS/ADL, only 20 mg memantine and 900 mg GV-971 had no significant difference from the placebo. Donepezil 5 mg and GV-971 900 mg did not increase the drug withdrawal rates due to various reasons or adverse reactions when compared to the placebo. Donepezil demonstrated superior binding to the protein and exhibited greater efficacy compared to other drugs.

CONCLUSION

ChEIs, memantine, and GV-971 all can slow the progression of AD but have different effects on respective assessments. Donepezil and GV-971 were relatively well tolerated.

A potential brain functional biomarker distinguishing patients with Crohn's disease with different disease stages: a resting-state fMRI study

Background

The previous studies have demonstrated that patients with Crohn's disease in remission (CD-R) have abnormal alterations in brain function. However, whether brain function changes in patients with Crohn's disease in activity (CD-A) and the relationship with CD-R are still unclear. In this study, we aimed to investigate whether the different levels of disease activity may differentially affect the brain function and to find the brain functional biomarker distinguishing patients with different disease stages by measuring the amplitude of low frequency fluctuations (ALFF).

Methods

121 patients with CD and 91 healthy controls (HCs) were recruited. The clinical and psychological assessment of participants were collected. The criteria for the disease activity were the Crohn's disease activity index (CDAI) scores. CD-R refers to CD patients in remission which the CDAI score is less than 150. Conversely, CD-A refers to CD patients in activity which the CDAI score is ≥150. The ALFF was compared among three groups by performing one-way analysis of variance, followed by a post hoc two-sample t-test. Differences among the groups were selected as seeds for functional connectivity analyses. We also investigated the correlation among clinical, psychological scores and ALFF. Binary logistic regression analysis was used to examine the unique contribution of the ALFF characteristics of the disease stages.

Results

There were widespread differences of ALFF values among the 3 groups, which included left frontal pole (FP_L), right supramarginal gyrus (SG_R), left angular gyrus (AG_L), right cingulate gyrus (CG_R), right intracalcarine cortex (IC_R), right parahippocampal gyrus (PG_R), right lingual gyrus (LG_R), right precuneous cortex (PC_R), left occipital fusiform gyrus (OFG_L). Significant brain regions showing the functional connections (FC) increased in FP_L, SG_R, PC_R and OFG_L between CD-A and HCs. The erythrocyte sedimentation rate had a negative correlation with the ALFF values in PC_R in the patients with CD. The phobic anxiety values had a negative correlation with the ALFF values in OFG_L. The psychoticism values had a negative correlation with ALFF values in the IC_R. And the hostility values had a positive correlation with the ALFF values in CG_R. Significant brain regions showing the FC increased in FP_L, SG_R, CG_R, PG_R, LG_R and OFG_L between CD-R and HCs. In binary logistic regression models, the LG_R (beta = 5.138, p = 0.031), PC_R (beta = 1.876, p = 0.002) and OFG_L (beta = 3.937, p = 0.044) was disease stages predictors.

Conclusion

The results indicated the significance of the altered brain activity in the different disease stages of CD. Therefore, these findings present a potential identify neuroimaging-based brain functional biomarker in CD. Additionally, the study provides a better understanding of the pathophysiology of CD.