STCGRU: A hybrid model based on CNN and BiGRU for mild cognitive impairment diagnosis

BACKGROUND AND OBJECTIVE

Early diagnosis of mild cognitive impairment (MCI) is one of the essential measures to prevent its further development into Alzheimer's disease (AD). In this paper, we propose a hybrid deep learning model for early diagnosis of MCI, called spatio-temporal convolutional gated recurrent unit network (STCGRU).

METHODS

The STCGRU comprises three bespoke convolutional neural network (CNN) modules and a bi-directional gated recurrent unit (BiGRU) module, which can effectively extract the spatial and temporal features of EEG and obtain excellent diagnostic results. We use a publicly available EEG dataset that has not undergone pre-processing to verify the robustness and accuracy of the model. Ablation experiments on STCGRU are conducted to showcase the individual performance improvement of each module.

RESULTS

Compared with other state-of-the-art approaches using the same publicly available EEG dataset, the results show that STCGRU is more suitable for early diagnosis of MCI. After 10-fold cross-validation, the average classification accuracy of the hybrid model reached 99.95 %, while the average kappa value reached 0.9989.

CONCLUSIONS

The experimental results show that the hybrid model proposed in this paper can directly extract compelling spatio-temporal features from the raw EEG data for classification. The STCGRU allows for accurate diagnosis of patients with MCI and has a high practical value.

Distinct plasma phosphorylated-tau proteins profiling for the differential diagnosis of mild cognitive impairment and Alzheimer's disease by plasmonic asymmetric nanobridge-based biosensor

The differential diagnosis between mild cognitive impairment (MCI) and Alzheimer's disease (AD) has been highly demanded for its effectiveness in preventing and contributing to early diagnosis of AD. To this end, we developed a single plasmonic asymmetric nanobridge (PAN)-based biosensor to differentially diagnose MCI and AD by quantitative profiling of phosphorylated tau proteins (p-tau) in clinical plasma samples, which revealed a significant correlation with AD development and progression. The PAN was designed to have a conductive junction and asymmetric structure, which was unable to be synthesized by the traditional thermodynamical methods. For its unique morphological characteristics, PAN features high electromagnetic field enhancement, enabling the biosensor to achieve high sensitivity, with a limit of detection in the attomolar regime for quantitative analysis of p-tau. By introducing support vector machine (SVM)-based machine learning algorithm, the improved diagnostic system was achieved for prediction of healthy controls, MCI, and AD groups with an accuracy of 94.47 % by detecting various p-tau species levels in human plasma. Thus, our proposed PAN-based plasmonic biosensor has a powerful potential in clinical utility for predicting the onset of AD progression in the asymptomatic phase.

Cerebrospinal fluid NPTX2 changes and relationship with regional brain metabolism metrics across mild cognitive impairment due to Alzheimer's disease

BACKGROUND

Neuronal pentraxin-2 (NPTX2), crucial for synaptic functioning, declines in cerebrospinal fluid (CSF) as cognition deteriorates. The variations of CSF NPTX2 across mild cognitive impairment (MCI) due to Alzheimer's disease (AD) and its association with brain metabolism remain elusive, albeit relevant for patient stratification and pathophysiological insights.

METHODS

We retrospectively analyzed 49 MCI-AD patients grouped by time until dementia (EMCI, n = 34 progressing within 2 years; LMCI, n = 15 progressing later/stable at follow-up). We analyzed demographic variables, cognitive status (MMSE score), and CSF NPTX2 levels using a commercial ELISA assay in EMCI, LMCI, and a control group of age-/sex-matched individuals with other non-dementing disorders (OND). Using [18F]FDG PET scans for voxel-based analysis, we explored correlations between regional brain metabolism metrics and CSF NPTX2 levels in MCI-AD patients, accounting for age.

RESULTS

Baseline and follow-up MMSE scores were lower in LMCI than EMCI (p value = 0.006 and p < 0.001). EMCI exhibited significantly higher CSF NPTX2 values than both LMCI (p = 0.028) and OND (p = 0.006). We found a significant positive correlation between NPTX2 values and metabolism of bilateral precuneus in MCI-AD patients (p < 0.005 at voxel level, p < 0.05 with family-wise error correction at the cluster level).

CONCLUSIONS

Higher CSF NPTX2 in EMCI compared to controls and LMCI suggests compensatory synaptic responses to initial AD pathology. Disease progression sees these mechanisms overwhelmed, lowering CSF NPTX2 approaching dementia. Positive CSF NPTX2 correlation with precuneus glucose metabolism links to AD-related metabolic changes across MCI course. These findings posit CSF NPTX2 as a promising biomarker for both AD staging and progression risk stratification.

Atrophy of hippocampal subfields and amygdala nuclei in subjects with mild cognitive impairment progressing to Alzheimer's disease

The hippocampus and amygdala are the first brain regions to show early signs of Alzheimer's Disease (AD) pathology. AD is preceded by a prodromal stage known as Mild Cognitive Impairment (MCI), a crucial crossroad in the clinical progression of the disease. The topographical development of AD has been the subject of extended investigation. However, it is still largely unknown how the transition from MCI to AD affects specific hippocampal and amygdala subregions. The present study is set to answer that question. We analyzed data from 223 subjects: 75 healthy controls, 52 individuals with MCI, and 96 AD patients obtained from the ADNI. The MCI group was further divided into two subgroups depending on whether individuals in the 48 months following the diagnosis either remained stable (N = 21) or progressed to AD (N = 31). A MANCOVA test evaluated group differences in the volume of distinct amygdala and hippocampal subregions obtained from magnetic resonance images. Subsequently, a stepwise linear discriminant analysis (LDA) determined which combination of magnetic resonance imaging parameters was most effective in predicting the conversion from MCI to AD. The predictive performance was assessed through a Receiver Operating Characteristic analysis. AD patients displayed widespread subregional atrophy. MCI individuals who progressed to AD showed selective atrophy of the hippocampal subiculum and tail compared to stable MCI individuals, who were undistinguishable from healthy controls. Converter MCI showed atrophy of the amygdala's accessory basal, central, and cortical nuclei. The LDA identified the hippocampal subiculum and the amygdala's lateral and accessory basal nuclei as significant predictors of MCI conversion to AD. The analysis returned a sensitivity value of 0.78 and a specificity value of 0.62. These findings highlight the importance of targeted assessments of distinct amygdala and hippocampus subregions to help dissect the clinical and pathophysiological development of the MCI to AD transition.

Prediction of conversion from mild cognitive impairment to Alzheimer's disease and simultaneous feature selection and grouping using Medicaid claim data

BACKGROUND

Due to the heterogeneity among patients with Mild Cognitive Impairment (MCI), it is critical to predict their risk of converting to Alzheimer's disease (AD) early using routinely collected real-world data such as the electronic health record data or administrative claim data.

METHODS

The study used MarketScan Multi-State Medicaid data to construct a cohort of MCI patients. Logistic regression with tree-guided lasso regularization (TGL) was proposed to select important features and predict the risk of converting to AD. A subsampling-based technique was used to extract robust groups of predictive features. Predictive models including logistic regression, generalized random forest, and artificial neural network were trained using the extracted features.

RESULTS

The proposed TGL workflow selected feature groups that were robust, highly interpretable, and consistent with existing literature. The predictive models using TGL selected features demonstrated higher prediction accuracy than the models using all features or features selected using other methods.

CONCLUSIONS

The identified feature groups provide insights into the progression from MCI to AD and can potentially improve risk prediction in clinical practice and trial recruitment.

Longitudinal trajectory effects of different MCI subtypes on general cognitive and daily functions in a population-based cohort of older adults

OBJECTIVES

To identify different mild cognitive impairment (MCI) phenotypes based on substantial relative impairment in specific cognitive domains and then characterize the complex process of general cognitive and daily functions over time in older adults with these MCI subtypes.

METHODS

A total of 1020 participants with MCI at baseline from the Alzheimer's Disease Neuroimaging Initiative (ADNI) were recruited. MCI subtypes were obtained based on neuropsychological tests in five cognitive domains: memory (M), visuospatial function (V), language (L), processing speed (P), and executive function (E). General cognitive function and daily function were measured by the Mini-Mental State Examination (MMSE) and the Functional Assessment Questionnaire (FAQ), respectively. Linear mixed models were fitted to curve their trajectories across different MCI subtypes.

RESULTS

Considering visuospatial function, subtypes were MO (memory impaired only), M&V (memory and visuospatial function impaired) and M&nV (memory impaired and visuospatial function non-impaired). Similar subtypes and naming rules were obtained based on language, executive function, and processing speed. Further, depending on the number of relative impaired cognitive domains M&S and M&M were obtained. Participants with MO had the highest prevalence in the sample (53.4 %), followed by M&nV (31.1 %). Participants with M&V had the highest mean age (74.69 years) at baseline and the greatest dementia conversion rate (53.2 %). The MMSE and FAQ score trajectories changed most slowly in participants with MO while fastest in those with M&V. Obvious different trajectories of both MMSE and FAQ scores were observed across different subtypes based on visuospatial function and executive function.

CONCLUSION

Compared to MO, individuals with multi-dimensional cognitive impairment have worse general cognitive and daily functions, especially for those with M&V.

A tensor decomposition scheme for EEG-based diagnosis of mild cognitive impairment

Mild Cognitive Impairment (MCI) is the primary stage of acute Alzheimer's disease, and early detection is crucial for the person and those around him. It is difficult to recognize since this mild stage does not have clear clinical signs, and its symptoms are between normal aging and severe dementia. Here, we propose a tensor decomposition-based scheme for automatically diagnosing MCI using Electroencephalogram (EEG) signals. A new projection is proposed, which preserves the spatial information of the electrodes to construct a data tensor. Then, using parallel factor analysis (PARAFAC) tensor decomposition, the features are extracted, and a support vector machine (SVM) is used to discriminate MCI from normal subjects. The proposed scheme was tested on two different datasets. The results showed that the tensor-based method outperformed conventional methods in diagnosing MCI with an average classification accuracy of 93.96% and 78.65% for the first and second datasets, respectively. Therefore, it seems that maintaining the spatial topology of the signals plays a vital role in the processing of EEG signals.

Effects of square dance exercise on cognitive function in elderly individuals with mild cognitive impairment: the mediating role of balance ability and executive function

BACKGROUND

Square dancing is a kind of aerobic fitness exercise without environmental restrictions that yields many benefits for physical and mental health; this exercise is popular among middle-aged and elderly people in China and in these populations in other countries. This study aimed to evaluate the effects of square dance exercise on the overall cognitive function of elderly individuals with mild cognitive impairment (MCI) and to research its mechanisms.

METHODS

A total of 60 elderly people with MCI (60-69 years old) without square dance experience were selected and randomly divided into an experimental group (n = 30) and a control group (n = 30). The experimental group participated in square dance exercise for 12 weeks, while the control group maintained their original lifestyle habits. One week before and after the intervention period, the overall cognitive function, physical fitness, and executive function of both groups were measured.

RESULTS

According to the results, square dance exercise directly improved the overall cognitive function of elderly individuals with MCI and indirectly affected overall cognitive function through the mediating effects of balance ability and executive function.

CONCLUSIONS

Square dance exercise represents a nonpharmacological intervention for the prevention and treatment of MCI. Importantly, it is best to combine this exercise with other forms of physical exercise and comprehensive treatment programs such as cognitive training, social interaction, and psychological intervention to realize its maximum effect.

Early postoperative neurocognitive complications in elderly patients: comparing those with and without preexisting mild cognitive impairment- a prospective study

BACKGROUND

As societies age, increasing numbers of older adults undergo surgeries with anesthesia. Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) frequently occur in older surgical patients. Most of these patients already have preoperative mild cognitive impairment (MCI). However, the correlation between MCI and POD remains unclear. This study aimed to determine the incidence of POD in elderly patients with and without preexisting MCI.

METHODS

A prospective study enrolled patients aged 60 years and above scheduled for major surgeries between December 2017 and April 2022. Preoperative MCI was determined by a Montreal Cognitive Assessment (MoCA) score between 18 and 24. POD was diagnosed using criteria from the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). POCD was characterized by a MoCA score reduction of 2 or more points from the preoperative score. The primary outcome was the incidence of POD within the first 72 h postoperatively. Secondary outcomes encompassed other postoperative complications, including POCD.

RESULTS

The study comprised 223 elderly patients with MCI and 56 without MCI. The incidence of POD was 16.6% in the MCI group and 14.3% in the non-MCI group (P = 0.839). POCD occurred in 24.3% of MCI patients and 50% of non-MCI patients (P = 0.001). There were no significant differences in other postoperative complications between the groups. Postoperatively, the MCI group notably declined in visuospatial, attention, and orientation domains, while the non-MCI group declined in all domains except delayed recall.

CONCLUSIONS

The incidence of POD was similar in the MCI and non-MCI groups. However, the non-MCI group demonstrated a higher incidence of POCD than the MCI group. This was identified by a reduction in postoperative MoCA scores for the visuospatial, naming, attention, language, abstraction, and orientation domains. These findings underscore the importance of postoperative cognitive assessments for both elderly patients with preexisting MCI and those with previously intact cognitive functions.

TRIAL REGISTRATION

This trial was retrospectively registered in the Thai Clinical Trials Registry on 15/01/2019 (registration number: TCTR20190115001).

The age-specific comorbidity burden of mild cognitive impairment: a US claims database study

BACKGROUND

Identifying individuals with mild cognitive impairment (MCI) who are likely to progress to Alzheimer's disease and related dementia disorders (ADRD) would facilitate the development of individualized prevention plans. We investigated the association between MCI and comorbidities of ADRD. We examined the predictive potential of these comorbidities for MCI risk determination using a machine learning algorithm.

METHODS

Using a retrospective matched case-control design, 5185 MCI and 15,555 non-MCI individuals aged ≥50 years were identified from MarketScan databases. Predictive models included ADRD comorbidities, age, and sex.

RESULTS

Associations between 25 ADRD comorbidities and MCI were significant but weakened with increasing age groups. The odds ratios (MCI vs non-MCI) in 50-64, 65-79, and ≥ 80 years, respectively, for depression (4.4, 3.1, 2.9) and stroke/transient ischemic attack (6.4, 3.0, 2.1). The predictive potential decreased with older age groups, with ROC-AUCs 0.75, 0.70, and 0.66 respectively. Certain comorbidities were age-specific predictors.

CONCLUSIONS

The comorbidity burden of MCI relative to non-MCI is age-dependent. A model based on comorbidities alone predicted an MCI diagnosis with reasonable accuracy.

Living well while providing support: validation of LTCQ-Carer for assessing informal carers' quality of life

PURPOSE

Despite international policies to support the health and wellbeing of informal (family) caregivers, there is no consensus on how to evaluate the effectiveness of carer support. We aimed to develop and validate a new quality-of-life measure for carers (LTCQ-Carer) and to assess its potential for use within a clinical pathway.

METHODS

Psychometric properties of LTCQ-Carer were tested through cognitive interviews (qualitative phase) and a pilot survey (quantitative phase). Participants were family caregivers of people recently diagnosed with mild cognitive impairment (MCI) or dementia, recruited through one of 14 memory clinics in south-east England. They self-completed the new measure and comparative existing measures (EQ-5D, ASCOT-Carer). Ongoing feedback from memory clinic staff on potential use of LTCQ-Carer was collected.

RESULTS

Interview participants (n = 10) found all draft items of LTCQ-Carer relevant and prompted inclusion of a new item on 'time to yourself'. Responses from survey participants (n = 107) indicated acceptability (low missing data), high internal reliability (Cronbach's α = 0.95), and a general construct (single factor loadings 0.43-0.86 for all items). Observation of predicted associations with EQ-5D and ASCOT-Carer supported construct validity. Responsiveness requires further testing as evidence was inconclusive. Clinical staff feedback on potential use was positive.

CONCLUSION

LTCQ-Carer is a valid new measure for assessing family caregivers' quality of life across broad health and social care domains, expanding the range of high-quality tools for evaluating carer support. When used concurrently with patient assessment, it could highlight carer needs and prompt appropriate family support at the earliest point in the clinical pathway.

The effectiveness of dance movement interventions for older adults with mild cognitive impairment, Alzheimer's disease, and dementia: A systematic scoping review and meta-analysis

OBJECTIVES

To synthesize evidence and summarize research findings related to the effectiveness and feasibility of dance movement intervention (DMI) in older adults with mild cognitive impairment (MCI), Alzheimer's disease (AD), and dementia; to systemically map existing research gaps and research directions for future practice.

METHODS

A systematic search was conducted using six electronic databases: Web of Science, PubMed, PsycINFO, MEDLINE, ScienceDirect, and Cochrane Central Register of Controlled Trials. The methodological quality of included studies was assessed using the Cochrane Risk of Bias Tool for Randomized Trials (RoB 2) and The Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I).

RESULTS

29 dance intervention studies (13 RCT studies) were included in the scoping review: 62% of MCI, 10% of AD, and 28% of dementia; a total of 1708 participants (Female=1247; Male=461) aged from 63.8 ( ± 5.24) to 85.8 ( ± 5.27) years old. Eight RCT studies were included in the meta-analysis; results indicated that dance interventions had a significant effect on global cognition, memory, balance, and significantly decreased depression. No significant effects were found for executive function.

CONCLUSIONS

Dance is a non-pharmacological, effective, affordable, and engaging intervention that can be used as a complementary treatment for older adults with MCI, AD, and dementia.

Cognitive profile of people with mild behavioral impairment in Brain Health Registry participants

OBJECTIVES

Dementia assessment includes cognitive and behavioral testing with informant verification. Conventional testing is resource-intensive, with uneven access. Online unsupervised assessments could reduce barriers to risk assessment. The aim of this study was to assess the relationship between informant-rated behavioral changes and participant-completed neuropsychological test performance in older adults, both measured remotely via an online unsupervised platform, the Brain Health Registry (BHR).

DESIGN

Observational cohort study.

SETTING

Community-dwelling older adults participating in the online BHR. Informant reports were obtained using the BHR Study Partner Portal.

PARTICIPANTS

The final sample included 499 participant-informant dyads.

MEASUREMENTS

Participants completed online unsupervised neuropsychological assessment including Forward Memory Span, Reverse Memory Span, Trail Making B, and Go/No-Go tests. Informants completed the Mild Behavioral Impairment Checklist (MBI-C) via the BHR Study Partner portal. Cognitive performance was evaluated in MBI+/- individuals, as was the association between cognitive scores and MBI symptom severity.

RESULTS

Mean age of the 499 participants was 67, of which 308/499 were females (61%). MBI + status was associated with significantly lower memory and executive function test scores, measured using Forward and Reverse Memory Span, Trail Making Errors and Trail Making Speed. Further, significant associations were found between poorer objectively measured cognitive performance, in the domains of memory and executive function, and MBI symptom severity.

CONCLUSION

These findings support the feasibility of remote, informant-reported behavioral assessment utilizing the MBI-C, supporting its validity by demonstrating a relationship to online unsupervised neuropsychological test performance, using a previously validated platform capable of assessing early dementia risk markers.

Validation of the mild cognitive impairment health literacy assessment scale (MCI-HLA scale) in middle-aged and older adults

OBJECTIVES

Health literacy (HL) is associated with early prevention of mild cognitive impairment (MCI), but a targeted comprehensive assessment tool is lacking. This study aims to psychometrically evaluate the MCI-HLA scale.

METHODS

This observational study was conducted in a tertiary-level hospital's physical examination center from October to December 2020. The middle-aged and older adults (N = 550, aged 41-80 years) completed the MCI-HLA questionnaire online. The validity of the MCI-HLA scale was assessed through content validity, exploratory factor analysis, confirmatory factor analysis (CFA), convergent validity, and discriminant validity. The internal reliability was measured using Cronbach's alpha, McDonald's Omega coefficient, and split-half reliability.

RESULTS

5 factors emerged, naming: Function (7 items), Knowledge (8 items), Practice (8 items), Attitude (4 items), and Motivation (3 items), explaining 72.42% of variance. The CFA revealed that five factors of the MCI-HLA scale fit well (χ2/df=4.076, RMSEA=0.078, SRMR=0.057, CFI=0.904, TLI=0.894). Good convergent validity was suggested by the Average Variance Extracted (AVE) values exceeding 0.50. Discriminant validity was demonstrated for all the square root AVE were higher than the correlation between the two factors. Internal consistency was high (Cronbach's alpha=0.875, McDonald's Omega coefficient=0.910, split-half reliability=0.949).

CONCLUSIONS

The MCI-HLA scale takes on high reliability and validity, suitable for assessing MCI-related health literacy in middle-aged and older adults. The MCI-HLA scale could enhance MCI health literacy assessment and supports tailored interventions for improved outcomes.

Effects and mechanisms of Tai Chi on mild cognitive impairment and early-stage dementia: a scoping review

BACKGROUND

Dementia is associated with cognitive and functional decline that significantly impacts quality of life. There is currently no cure for dementia, thus, it is important to manage dementia in the early stages and delay deterioration. Previous studies have documented a range of health benefits of Tai Chi in people with early-stage dementia, however, none have systematically integrated these effects with their underlying mechanisms. The aims of this study were to (1) identify the neurocognitive, psychological, and physical health benefits of Tai Chi oi people with early-stage dementia, and (2) explore the underlying mechanisms of these effects.

METHODS

We searched systematic reviews (SRs) and randomised control trials (RCTs) on Tai Chi for adults aged 50 years and older with mild cognitive impairment (MCI) or early-stage dementia in MEDLINE, PubMed, Cochrane Library, EMBASE, and major Chinese databases. No language or publication restrictions were applied. Risk of bias was assessed.

RESULTS

Eight SRs with meta-analyses and 6 additional published RCTs revealed inconsistent findings of Tai Chi on improving global cognitive function, attention and executive function, memory and language, and perceptual-motor function. There was no significant between-group difference in depressive symptoms. The results from the RCTs showed that Tai Chi can reduce arthritis pain and slow the progress of dementia. No studies on MCI or early-stage dementia investigating the underlying mechanisms of Tai Chi were identified. Instead, nine mechanistic studies on healthy adults were included. These suggested that Tai Chi may improve memory and cognition via increased regional brain activity, large-scale network functional connectivity, and regional grey matter volume.

CONCLUSION

The effects of Tai Chi on neurocognitive outcomes in people with MCI and early-stage dementia are still inconclusive. Further high-quality clinical trials and mechanistic studies are needed to understand if and how Tai Chi may be applied as a successful intervention to delay deterioration and improve the quality of life in people with an increased risk of cognitive decline.

Amelioration of Cognitive and Olfactory System Deficits in APOE4 Transgenic Mice with DHA Treatment

Olfactory dysfunction and atrophy of olfactory brain regions are observed early in mild cognitive impairment and Alzheimer disease. Despite substantial evidence showing neuroprotective effects in MCI/AD with treatment of docosahexaenoic acid (DHA), an omega-3 fatty acid, few studies have assessed DHA and its effects on the olfactory system deficits. We therefore performed structural (MRI), functional (olfactory behavior, novel object recognition), and molecular (markers of apoptosis and inflammation) assessments of APOE4 and wild-type mice ± DHA treatment at 3, 6, and 12 months of age. Our results demonstrate that APOE4 mice treated with the control diet show recognition memory deficits, abnormal olfactory habituation, and discrimination abilities and an increase in IBA-1 immunoreactivity in the olfactory bulb. These phenotypes were not present in APOE4 mice treated with a DHA diet. Alterations in some brain regions' weights and/or volumes were observed in the APOPE4 mice and may be due to caspase activation and/or neuroinflammatory events. These results suggest that the consumption of a diet rich in DHA may provide some benefit to E4 carriers but may not alleviate all symptoms.

Resting state EEG rhythms in different stages of chronic kidney disease with mild cognitive impairment

Here, we tested that standard eyes-closed resting-state electroencephalographic (rsEEG) rhythms may characterize patients with mild cognitive impairment due to chronic kidney disease at stages 3-4 (CKDMCI-3&4) in relation to CKDMCI patients under hemodialysis (CKDMCI-H) and mild cognitive impairment (MCI) patients with cerebrovascular disease (CVMCI). Clinical and rsEEG data in 22 CKDMCI-3&4, 15 CKDMCI-H, 18 CVMCI, and 30 matched healthy control (HC) participants were available in a national archive. Spectral rsEEG power density was calculated from delta to gamma frequency bands at scalp electrodes. Results showed that (1) all MCI groups over the HC group showed decreased occipital rsEEG alpha power density; (2) compared to the HC and CVMCI groups, the 2 CKDMCI groups had higher rsEEG delta-theta power density; and (3) the CKDMCI-3&4 group showed the lowest parietal rsEEG alpha power density. The present rsEEG measures may be useful to monitor the impact of circulating uremic toxins on brain regulation of cortical arousal for quiet vigilance in CKDMCI patients.

A systematic review of the safety and efficacy on cognitive function of herbal and nutritional medicines in older adults with and without subjective cognitive impairment

BACKGROUND

Subjective cognitive impairment (SCI) substantially increases dementia risk and is often conceptualised as the preclinical asymptomatic phase of the cognitive decline continuum. Due to the lack of pharmacological interventions available to treat SCI and reduce dementia risk, and the popularity of herbal and nutritional medicines, the primary aim of this review was to investigate the efficacy on cognitive function and safety of herbal and nutritional medicines (relative to a control) for older adults with and without SCI. The secondary aims were to describe the study characteristics and assess the methodological quality of included studies.

METHOD

Five databases (Cochrane, MEDLINE, CINAHL, PsycInfo, and EMBASE) were searched from database inception with weekly alerts established until review finalisation on 18 September 2022. Articles were eligible if they included the following: study population of older adults with and without SCI, herbal and nutritional medicines as an intervention, evaluated cognitive outcomes and were randomised control trials.

RESULTS

Data were extracted from 21/7666 eligible full-text articles, and the risk of methodological bias was assessed (with SCI = 9/21; without SCI = 12/21). Most studies (20/21) employed parallel, randomised, placebo-controlled designs and were 12 weeks in length. Herbal supplements were widely used (17/21), namely a form of Ginkgo biloba (8/21) or Bacopa monnieri (6/21). Measures of cognition varied across studies, with 14/21 reporting improvements in at least one domain of cognitive functioning over time, in the intervention group (compared to control). A total of 14/21 studies were deemed as having an overall high methodological risk of bias, 6/21 had some concerns, and only one study (using an SCI population) was assessed as having a low risk of methodological bias.

CONCLUSIONS

Overall, this review found that there is a low quality of evidence regarding the efficacy of cognitive function and safety of herbal and nutritional medicines for older adults with and without SCI, due to a high risk of bias across studies. Additionally, further work needs to be done in classifying and understanding SCI and selecting appropriate trial primary outcomes before future studies can more accurately determine the efficacy of interventions for this population.

The Effects of Transcutaneous Vagus Nerve Stimulation on Functional Connectivity Within Semantic and Hippocampal Networks in Mild Cognitive Impairment

Better treatments are needed to improve cognition and brain health in people with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Transcutaneous vagus nerve stimulation (tVNS) may impact brain networks relevant to AD through multiple mechanisms including, but not limited to, projection to the locus coeruleus, the brain's primary source of norepinephrine, and reduction in inflammation. Neuropathological data suggest that the locus coeruleus may be an early site of tau pathology in AD. Thus, tVNS may modify the activity of networks that are impaired and progressively deteriorate in patients with MCI and AD. Fifty patients with MCI (28 women) confirmed via diagnostic consensus conference prior to MRI (sources of info: Montreal Cognitive Assessment Test (MOCA), Clinical Dementia Rating scale (CDR), Functional Activities Questionnaire (FAQ), Hopkins Verbal Learning Test - Revised (HVLT-R) and medical record review) underwent resting state functional magnetic resonance imaging (fMRI) on a Siemens 3 T scanner during tVNS (left tragus, n = 25) or sham control conditions (left ear lobe, n = 25). During unilateral left tVNS, compared with ear lobe stimulation, patients with MCI showed alterations in functional connectivity between regions of the brain that are important in semantic and salience functions including regions of the temporal and parietal lobes. Furthermore, connectivity from hippocampi to several cortical and subcortical clusters of ROIs also demonstrated change with tVNS compared with ear lobe stimulation. In conclusion, tVNS modified the activity of brain networks in which disruption correlates with deterioration in AD. These findings suggest afferent target engagement of tVNS, which carries implications for the development of noninvasive therapeutic intervention in the MCI population.

New balance capability index as a screening tool for mild cognitive impairment

BACKGROUND

Mild cognitive impairment (MCI) is not just a prodrome to dementia, but a very important intervention point to prevent dementia caused by Alzheimer's disease (AD). It has long been known that people with AD have a higher frequency of falls with some gait instability. Recent evidence suggests that vestibular impairment is disproportionately prevalent among individuals with MCI and dementia due to AD. Therefore, we hypothesized that the measurement of balance capability is helpful to identify individuals with MCI.

METHODS

First, we developed a useful method to evaluate balance capability as well as vestibular function using Nintendo Wii balance board as a stabilometer and foam rubber on it. Then, 49 healthy volunteers aged from 56 to 75 with no clinically apparent cognitive impairment were recruited and the association between their balance capability and cognitive function was examined. Cognitive functions were assessed by MoCA, MMSE, CDR, and TMT-A and -B tests.

RESULTS

The new balance capability indicator, termed visual dependency index of postural stability (VPS), was highly associated with cognitive impairment assessed by MoCA, and the area under the receiver operating characteristic (ROC) curve was more than 0.8, demonstrating high sensitivity and specificity (app. 80% and 60%, respectively).

CONCLUSIONS

Early evidence suggests that VPS measured using Nintendo Wii balance board as a stabilometer helps identify individuals with MCI at an early and preclinical stage with high sensitivity, establishing a useful method to screen MCI.

Homocysteine - A predictor for five year-mortality in patients with subjective cognitive decline, mild cognitive impairment and Alzheimer's dementia

BACKGROUND

Subjective Cognitive Decline (SCD) and Mild Cognitive Impairment (MCI) are preclinical stages of Alzheimer's Disease (AD), which is the most common entity of dementia. Homocysteine is an amino acid in the methionine cycle, and many studies revealed a significant association between elevated homocysteine serum levels and the progression of dementia. The primary objective of this retrospective study was to investigate whether elevated homocysteine serum levels could be associated with mortality and neuropsychological test results in individuals suffering from SCD, MCI or AD.

METHODS

This study is a single-center explorative retrospective data analysis with 976 data protocols from the Memory Outpatient's Clinic of the Medical University of Vienna included. All patients underwent a neurological examination, a laboratory blood test, and neuropsychological testing to establish a diagnosis of either SCD, MCI, or AD. Data was evaluated by Kaplan-Meier functions, factor analysis, and binary logistic regression models.

RESULTS

Patients with AD showed significantly higher mean homocysteine levels (SCD 12.15 ± 4.71, MCI 12.80 ± 4.81, AD 15.0 ± 6.44 μmol/L) compared to those with SCD and MCI (p ≤ .001). The mean age of patients with AD (75.2 ± 7.8) was significantly older at the time of testing than of patients with MCI (69.1 ± 9.6) or SCD (66.8 ± 9.3). Since homocysteine levels increase with age, this could be a possible explanation for the higher levels of AD patients. The age at death did not differ significantly between all diagnostic subgroups, resulting in the shortest survival times for AD patients. Homocysteine levels were negatively associated with in Mini-Mental State Examination (MMSE) and Neuropsyhcological Test Battery Vienna (NTBV) factors F1-F4 (F1 = attention, F2 = memory, F3 = executive functions, F4 = naming/verbal comprehension). Moreover, higher homocysteine levels significantly predicted shorter five-year survival in the logistic regression models, even after adjusting for age, diagnostic subgroups, sex, years of education and results of neuropsychological testing.

CONCLUSION

The results of this study suggest that homocysteine levels are independently associated with impaired cognitive function and increased five-year mortality.

Assessment of subjective and objective masticatory function among elderly individuals with mild cognitive impairment

BACKGROUND

Masticatory function is known to be related to cognitive ability; therefore, factors for improving masticatory function should be identified.

AIMS

This study aimed to identify factors influencing masticatory function associated with mild cognitive impairment (MCI) in elderly individuals.

METHODS

A total of 123 elderly participants [mean age: 76.5 ± 6.5 years; 82 females (66.7%), 41 males (33.3%)] were included. Cognitive function was evaluated by the Korean version of the Mini-Mental State Examination (KMMSE). Questionnaires for subjective evaluation were administered, and dynamic objective masticatory function evaluations, including chewing tests and bite force measurements, were performed. Intergroup differences were evaluated by the Wilcoxon rank-sum and chi-square test, and correlations between cognitive ability and masticatory function were evaluated by multilinear logistic regression.

RESULTS

The number of teeth, number of posterior teeth, bite force, masticatory ability index (MAI) and posterior support status showed significant differences between the normal (KMMSE > 23) and MCI (KMMSE ≤ 23) groups. However, only the MAI, representing dynamic masticatory performance, was significantly associated with MCI regardless of age, sex and removable prostheses. The number of teeth and posterior teeth, bite force, subjective masticatory ability and posterior occlusal support showed no significant association with MCI.

DISCUSSION

These results suggested the importance of chewing function for preventing the progression of cognitive impairment.

CONCLUSIONS

Considering that only the MAI was significantly associated with MCI, it is more important to improve chewing efficiency by harmonizing therapeutic prosthetics with the surrounding masticatory system than simply increasing the number of teeth to prevent or delay cognitive impairment in elderly individuals.

Effects of Kami Guibi-tang in patients with mild cognitive impairment: study protocol for a phase III, randomized, double-blind, and placebo-controlled trial

BACKGROUND

Amnestic mild cognitive impairment (aMCI) is often considered a precursor to Alzheimer's disease (AD) and represents a key therapeutic target for early intervention of AD. However, no treatments have been approved for MCI at present. Our previous pilot study has shown that Kami Guibi-tang (KGT), a traditional herbal prescription widely used in Korean medicine for treating amnesia, might be beneficial for improving general cognitive function of aMCI patients. We will conduct a larger-scale clinical trial to validate the findings of our pilot study and further examine the efficacy and safety of KGT in aMCI.

METHODS

This trial is designed as a randomized, double-blind, placebo-controlled clinical trial. A total of 84 aMCI patients will be recruited and randomized into the treatment and control groups. Participants will be administered either KGT or placebo granules for 24 weeks, with a follow-up period of 12 weeks after the last treatment. Primary outcomes will include changes in cognitive performance assessed using a neuropsychological test battery, called the Seoul Neuropsychological Screening Battery, between the baseline, post-intervention visit, and follow-up visit (24th and 36th week, respectively). Secondary outcomes will involve the rate of progression to AD, changes in neuroimaging signals assessed using structural magnetic resonance imaging (MRI), resting-state functional MRI (rs-fMRI), and task-based fMRI, and changes in blood biomarkers measured by the ratio of plasma amyloid-β 42/40 levels (Aβ42/Aβ40) between the baseline and post-intervention visit (24th week). For safety assessments, blood chemistry tests and electrocardiograms (ECG) will also be performed.

DISCUSSION

This study aims to provide confirmatory evidence of the effect of the Korean herbal medicine, KGT, on improving cognitive function in patients with aMCI. We will identify the possible mechanisms underlying the effects of KGT using neuroimaging signals and blood biomarkers.

TRIAL REGISTRATION

Korean Clinical Trial Registry ( https://cris.nih.go.kr/cris/search/detailSearch.do/16918; Registration number: KCT0007039; Date of registration: February 24, 2022).

Cognitive Impairment in Older Adults: Epidemiology, Diagnosis, and Treatment

Cognitive impairment and dementia affect dozens of millions of people worldwide and cause significant distress to patients and caregivers and a financial burden to families and health care systems. Careful history-taking, cognitive and physical examination, and supplemental neuroimaging and fluid-based biomarkers can accurately diagnose neurocognitive disorders. Management includes non-pharmacological and pharmacological treatments tailored to the etiology and to the individual.

Longitudinal measurement properties of the Montreal Cognitive Assessment

INTRODUCTION

The Montreal Cognitive Assessment (MoCA) has started to be used in longitudinal investigations to measure cognition trends but its measurement properties over time are largely unknown. This study aimed to examine the longitudinal measurement invariance of individual MoCA items.

METHOD

We used four waves of data collected between 2014 and 2017 from a cohort study on health and well-being of older adults from twelve public housing estates in Hong Kong. We identified people aged 65 years or older at baseline who answered the MoCA items across all time points and had a valid indicator of educational level. A total of 1028 participants were included. We applied confirmatory factor analysis of ordinal variables to examine measurement invariance of the Chinese (Cantonese) MoCA (version 7.0) items across four time points, stratified by educational level, where invariant items were identified by sequential model comparisons.

RESULTS

Four items exhibited a lack of measurement invariance across the four time points in both education groups (Clock Hand, abstraction, Delayed Recall, and Orientation). The items Cube and Sentence Repetition lacked longitudinal measurement invariance only in the "some education" group and the items Clock Shape and Clock Number only in the "no education" group. However, accounting for the lack of measurement invariance did not substantially affect classification properties for major neurocognitive disorder and mild cognitive impairment.

CONCLUSIONS

Our findings support using MoCA to assess changes in cognition over time in the study population while calling for future research in other populations.

Flurbiprofen axetil alleviates the effect of formalin-induced inflammatory pain on the cognitive function of rats with mild cognitive impairment through the AMPKα/NF-κB signaling pathway

Background

Mild cognitive impairment (MCI) as a prestage of dementia shares the most risk factors with dementia. In the present study, we explored the effect of flurbiprofen axetil on reducing the response of the central nervous system to inflammatory factors and anti-inhibiting apoptosis with the aim of developing a formalin-induced inflammatory pain model using MCI rats.

Methods

Rats were subjected to sham operation (Sham group) or formalin-induced inflammatory pain, with or without flurbiprofen axetil (10 mg/kg). MCI rats were administered D-galactose (1,000 mg/kg) for 7 days subcutaneously. Thereafter, formalin was injected subcutaneously into the hind paws of rats, while sham group was injected with only normal saline. In the formalin/flurbiprofen group (F/F group), flurbiprofen axetil was injected into the tail vein 15 min before formalin was given, and the formalin/saline group (F/S group) used normal saline instead of the drug for injection. The pain score was recorded, and the time-score curve was drawn. The escape latency time and the number of times crossing the platform were recorded. The expression of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), AMP-activated protein kinase-α (AMPKα), and nuclear factor-κB p65 (NF-κB p65) in hippocampal tissue was determined. Varying degrees of pathological changes in the hippocampal CA1 region were observed.

Results

The II phase pain score of rats in the F/F group was lower than that of the F/S group rats (P<0.05). The evasion incubation period and the number of platform crossings increased in both the F/F group and the F/S group (P<0.05), and were more significant in the F/S group. The relative content of AMPKα increased sequentially in the 3 groups, and the difference between the two comparisons of each group was statistically significant (P<0.05). The relative content of IL-6, TNF-α and NF-κB in the F/S group was greater than that of the F/F group, and the difference was statistically significant (P<0.001). Pathological morphological observations can be seen that the phenomena of nuclear consolidation, deep staining, and neuronal apoptosis occur, and the F/S group is more obvious.

Conclusions

Flurbiprofen axetil can reduce the inflammatory response and cognitive function of an inflammatory pain model using MCI rats through the AMPKα/NF-κB signaling pathway.

Changes in sensory, postural stability and gait functions depending on cognitive decline, and possible markers for detection of cognitive status

Background

Numerous people never receive a formal dementia diagnosis. This issue can be addressed by early detection systems that utilize alternative forms of classification, such as gait, balance, and sensory function parameters. In the present study, said functions were compared between older adults with healthy cognition, older adults with low executive function, and older adults with cognitive impairment, to determine which parameters can be used to distinguish these groups.

Results

A group of cognitively healthy older men was found to have a significantly greater gait cadence than both the low executive function group (113.1 ± 6.8 vs. 108.0 ± 6.3 steps/min, p = 0.032) and the cognitively impaired group (113.1 ± 6.8 vs. 107.1 ± 7.4 steps/min, p = 0.009). The group with low executive function was found to have more gait stability than the impaired cognition group, represented by the single limb support phase (39.7 ± 1.2 vs. 38.6 ± 1.3%, p = 0.027). Additionally, the healthy cognition group had significantly greater overall postural stability than the impaired cognition group (0.6 ± 0.1 vs. 1.1 ± 0.1, p = 0.003), and the low executive function group had significantly greater mediolateral postural stability than the impaired cognition group (0.2 ± 0.1 vs. 0.6 ± 0.6, p = 0.012). The low executive function group had fewer mistakes on the sentence recognition test than the cognitively impaired (2.2 ± 3.6 vs. 5.9 ± 6.4, p = 0.005). There were no significant differences in visual capacity, however, the low executive function group displayed an overall greatest ability.

Conclusions

Older adults with low executive function showcased a lower walking pace, but their postural stability and sensory functions did not differ from those of the older adults with healthy cognition. The variables concluded as good cognitive status markers were (1) gait cadence for dividing cognitively healthy from the rest and (2) single limb support portion, mediolateral stability index, and the number of mistakes on the sentence recognition test for discerning between the low executive function and cognitive impairment groups.

Development and validation of a nomogram for predicting mild cognitive impairment in middle-aged and elderly people

BACKGROUND

Mild cognitive impairment (MCI) is a clinical cognitive impairment state between dementia and normal aging. Early identification of MCI is beneficial, and it can delay the development of dementia. We aimed to develop and validate a prediction model to predict MCI of middle-aged and elderly people (aged 45 years and over).

METHODS

According to 478 middle-aged and elderly people (48-85 years old) from a cross-sectional study, we developed and validated a predictive nomogram. The least absolute shrinkage and selection operator (LASSO) regression model and multivariate logistic regression analysis were used to select variables and develop a prediction model. The performance of the nomogram was evaluated in terms of its discriminative power, calibration, and decision curve analysis (DCA).

RESULTS

The predictive nomogram was composed of the following: age, gender, education level, residence, and reading. The model showed good discrimination power (area under receiver-operating characteristic (ROC) curve was 0.8704) and good calibration. Similar results were seen in 10-fold cross-validation. The nomogram showed clinically useful in DCA analysis.

CONCLUSION

This predictive nomogram provides researchers with a practical tool for predicting MCI. The variables included in this nomogram were readily available. The population used for this nomogram was middle-aged and elderly people.

Cellular transcriptional alterations of peripheral blood in Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD), a progressive neurodegenerative disease, is the most common cause of dementia worldwide. Accumulating data support the contributions of the peripheral immune system in AD pathogenesis. However, there is a lack of comprehensive understanding about the molecular characteristics of peripheral immune cells in AD.

METHODS

To explore the alterations of cellular composition and the alterations of intrinsic expression of individual cell types in peripheral blood, we performed cellular deconvolution in a large-scale bulk blood expression cohort and identified cell-intrinsic differentially expressed genes in individual cell types with adjusting for cellular proportion.

RESULTS

We detected a significant increase and decrease in the proportion of neutrophils and B lymphocytes in AD blood, respectively, which had a robust replicability across other three AD cohorts, as well as using alternative algorithms. The differentially expressed genes in AD neutrophils were enriched for some AD-associated pathways, such as ATP metabolic process and mitochondrion organization. We also found a significant enrichment of protein-protein interaction network modules of leukocyte cell-cell activation, mitochondrion organization, and cytokine-mediated signaling pathway in neutrophils for AD risk genes including CD33 and IL1B. Both changes in cellular composition and expression levels of specific genes were significantly associated with the clinical and pathological alterations. A similar pattern of perturbations on the cellular proportion and gene expression levels of neutrophils could be also observed in mild cognitive impairment (MCI). Moreover, we noticed an elevation of neutrophil abundance in the AD brains.

CONCLUSIONS

We revealed the landscape of molecular perturbations at the cellular level for AD. These alterations highlight the putative roles of neutrophils in AD pathobiology.

EEG asymmetry and cognitive testing in MCI identification

BACKGROUND

Finding the baseline resting-state EEG markers for early identification of cognitive decline can contribute to the identification of individuals at risk of further change. Potential applications include identifying participants for clinical trials, early treatment, and evaluation of treatment, accessible even from a community setting.

METHODS

Analyses were completed on a sample of 99 (ages 60-90) consensus-diagnosed, community-dwelling African Americans (58 cognitively typical/HC, and 41 mildly cognitively impaired/MCI), who were recruited from the Michigan Alzheimer's Disease Research Center (MADRC) and the Wayne State University Institute of Gerontology. In addition to neuropsychological testing with CogState and Toolbox computerized batteries, resting-state EEGs (rsEEG, eyes closed) were acquired before and after participants were engaged in a visual motion direction discrimination task. rsEEG frontal alpha asymmetry (FAA) and frontal beta asymmetry (FBA) were calculated.

RESULTS

FAA showed no difference across groups for the pre-task resting state. FBA was significantly different between groups, with more asymmetric frontal beta in MCI. Both physiological indices, however, along with computerized neuropsychological tests were significant predictors in logistic regression classification of MCI vs. control participants.

CONCLUSION

rsEEG asymmetries can contribute significantly to successful discrimination of older persons with MCI from those without, over and above cognitive testing, alone.

The effects of dexmedetomidine on the cognitive function of mild cognitive impairment (MCI) rats

Background

The study sought to investigate the effects of dexmedetomidine (DEX) on cognitive function after anesthesia and to examine its actual mechanism.

Methods

A total of 48 rats were injected with d-galactose (D-gal) 1,000 mg·kg⁻¹·d⁻¹ and normal saline at the neck and back for 1 week to establish rats with mild cognitive impairment (MCI) and conduct behavioral tests. Sevoflurane was inhaled and DEX was pumped into each group respectively. Morris water maze (MWM) test was conducted 24 hours later. The inflammatory factors interleukin (IL)-1, interleukin (IL)-6, and a tumor necrosis factor (TNF)-α in brain homogenate were quantitatively measured by enzyme-linked immunosorbent assay (ELISA) on the next day. The apoptosis of hippocampal cells was observed by hematoxylin-eosin staining (HE staining).

Results

In relation to the model establishment, we found that there was no significant difference in body weight and swimming speed before and after modeling. There was no statistically significant difference in the escape latency between Groups A, B, C, and D before modeling. After modeling, there was no statistical difference in the escape latency between Groups A, B, and C, but the difference was statistically significant when compared to Group D (P<0.05). In relation to the DEX intervention, we found that compared to Group C, MWM test performance in Groups A and B was considerably worse longer escape latencies and fewer platform crossings within 90 seconds), and were more significant in Group A. Compared with Group D, the levels of inflammatory cytokines of the brain homogenates were elevated, and this elevation was highest in Group A, followed by Group B; the pathological changes were consistent with changes in behavioral tests. In Group A, there were obvious disorders of glial cell arrangement, apoptosis and deletion. There was no significant change in Group D. And the changes of vertebral cells in Group B and Group C were slight, with orderly arrangement and intact cell structure.

Conclusions

DEX inhibits the apoptosis of hippocampal cells and reduces the cognitive dysfunction of rats with MCI induced by D-gal via the inhibition of the release of inflammatory cytokines.

Low serum apelin levels are associated with mild cognitive impairment in Type 2 diabetic patients

BACKGROUND

Apelin is a new adipokine that is secreted by adipocytes, and is associated with insulin resistance (IR), inflammation, and obesity. This study was designed to investigate the role of apelin in type 2 diabetes mellitus (T2DM) patients with mild cognitive impairment (MCI).

METHODS

A total of 235 patients with T2DM were included. The cognitive function of patients was evaluated using Montreal Cognitive Assessment (MoCA) tool, then patients were divided into MCI group and non-MCI group according to the MoCA score. Blood sample was analyzed for the level of apelin by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The MCI group (n = 73) presented lower serum apelin levels compared with the patients with normal cognitive function (P < 0.001). Apelin levels showed significantly negative correlation with diabetes duration, triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C, creatinine and high sensitivity C-reactive protein (hs-CRP), and positive correlation with high-density lipoprotein cholesterol (HDL-C) and brain-derived neurotrophic factor (BDNF). Multivariable logistic regression analysis indicated that serum apelin (OR = 0.304, 95%CI: 0.104-0.886, P = 0.029), as well as education levels, diabetes duration, cardiovascular disease, serum HbA1c, HDL-C, creatinine, and BDNF, were independent risk factors of MCI in patients with T2DM.

CONCLUSIONS

Serum apelin level is reduced in T2DM patients with MCI. Apelin might has protective effect against cognitive impairment and serve as a serum biomarker of T2DM.

Combining PET with MRI to improve predictions of progression from mild cognitive impairment to Alzheimer's disease: an exploratory radiomic analysis study

Background

This study aimed to explore the potential of a combination of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) and magnetic resonance imaging (MRI) to improve predictions of conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD). The predictive performances and specific associated biomarkers of these imaging techniques used alone (single-modality imaging) and in combination (dual-modality imaging) were compared.

Methods

This study enrolled 377 patients with MCI and 94 healthy control participants from 2 medical centers. Enrolment was based on the patients' brain MRI and PET images. Radiomic analysis was performed to evaluate the predictive performance of dual-modality 18F-FDG PET and MRI scans. Regions of interest (ROIs) were determined using an a priori brain atlas. Radiomic features in these ROIs were extracted from the MRI and 18F-FDG PET scan data. These features were either concatenated or used separately to select features and construct Cox regression models for prediction in each modality. Harrell's concordance index (C-index) was then used to assess the predictive accuracies of the resulting models, and correlations between the MRI and 18F-FDG PET features were evaluated.

Results

The C-indices for the two test datasets were 0.77 and 0.80 for dual-modality 18F-FDG PET/MRI, 0.75 and 0.73 for single-modality 18F-FDG PET, and 0.74 and 0.76 for single-modality MRI. In addition, there was a significant correlation between the crucial image signatures of the different modalities.

Conclusions

These results indicate the value of imaging features in monitoring the progress of MCI in populations at high risk of developing AD. However, the incremental benefit of combining 18F-FDG PET and MRI is limited, and radiomic analysis of a single modality may yield acceptable predictive results.

Evaluation of the impact of cataract surgery on cognitive function in very elderly patients: a prospective, observational study

AIM

To evaluate the impact of cataract surgery on cognitive function in very elderly patients (≥ 85 years).

METHODS

A prospective, nonrandomized, comparative study of very elderly patients (≥ 85 years), and elderly patients (≥ 65 < 85 years) scheduled for first time cataract surgery. Cognitive function, quality of life (QoL), best corrected visual acuity (BCVA), endothelial cell count (ECC), and central corneal thickness (CCT) were assessed at 90 days before surgery (T0), at surgery (T1), and at 30 (T2) and 90 days (T3) after surgery. Macular thickness (MT) was evaluated at T2. Six-item cognitive impairment test (6CIT) was used to evaluate cognitive function while the Catquest-9SF test was used to assess QoL. The confusion assessment method (CAM) was used to evaluate the presence of delirium episodes at within 48 h from T1.

RESULTS

A total of 78 patients (very elderly n = 24, elderly n = 54) were enrolled; average age 80.3 ± 6.2 years old. Significant improvements for cognitive function, BCVA, QoL (p < 0.01) during the observational period were observed among the cohort. A greater improvement in cognitive function was observed in the very elderly patients between T1 and T2 (p = 0.02), while there was no difference in BCVA and QoL between the groups. There were no significant differences in ECC and CCT changes between the groups. No delirium episodes or significant macular abnormalities were registered.

CONCLUSIONS

Cataract surgery in very elderly patients seems to offer a greater improvement in cognitive function as compared to elderly patients, and it is associated with a significant improvement in QoL, without any incidence of postoperative delirium.

Evaluation of mild cognitive impairment genetic susceptibility risks in a Chinese population

BACKGROUND

Mild cognitive impairment (MCI) is a kind of non-functional cognitive decline between normal aging and dementia. With the increase of individual age, the quality of cognitive function has become a more and more important topic. The study of gene loci in patients with MCI is essential for the prevention of dementia. In this study, we evaluate the gene polymorphism in Chinese Han patients with MCI by propensity score matching (PSM) and comparing them to healthy control (HC) subjects.

METHODS

Four hundred seventeen patients with mild cognitive impairment and 508 healthy people were included. The two groups were matched by applying one-to-one PSM, and the matching tolerance was set to 0.002. The matching covariates included gender,age,occupation,marital status,living mode. Then, a case-control associated analysis was conducted to analyze the genotype and allele frequencies of single nucleotide polymorphisms (SNPs) in the MCI group and the control group.

RESULTS

Three hundred eleven cases were successfully matched in each group, and there was no statistical difference on all the matching variables, gender, age, occupation, marital status, living mode between two groups after the match (P > 0.05). The allele frequency of bridging integrator 1(BIN1) rs7561528 showed minimal association with MCI in the Han Chinese population (P = 0.01). Compared with the healthy control (HC) group, A allele frequency of MCI group patients was significantly decreased. The genotype frequency of BIN1 rs6733839 showed minimal association with MCI in the recessive model (P = 0.03). The genotype frequency of rs7561528 showed minimal association with MCI in the codominant, dominant, overdominant, and log-additive model (P < 0.05). The genotype frequencies of StAR-related lipid transfer domain 6 (STARD6) rs10164112 showed nominal association with MCI in the codominant, dominant, and log-additive model (P < 0.05). Unfortunately, the significant differences did not survive Benjamini-Hochberg false discovery rate correction (adjusted P > 0.05). The patients with SPI1 rs1057233 may be the protective factor of MCI (OR = 0.733, 95%CI 0.625-0.859, P < 0.001), and patients with APOE rs10164112 may be a risk factor for MCI (OR = 1.323, 95%CI 1.023-1.711, P = 0.033).

CONCLUSIONS

The polymorphisms of rs7561528, rs6733839 loci in the BIN1 gene, and rs1057233 loci in the SPI1 gene may be associated with the MCI in Chinese Han population. APOE gene was the risk factor of MCI, but further verification in a large sample population is still needed.

Subjective cognitive decline in idiopathic Parkinson´s disease: A systematic review

Cognitive symptoms of Parkinson's disease (PD) have been long underestimated, but are some of the most disabling non-motor features of the disease. In order to establish signs that allow for earlier detection of cognitive decline in PD, the concept of `subjective cognitive decline´ (SCD) has gained a growing interest. SCD refers to patients who report a decline in subjective cognitive capacities, while their results on neuropsychological tests are within the normal performance range, indicating adequate cognitive functions. The aim of this review was to evaluate the concept of SCD in PD and give an overview of the current research. A systematic literature search in PubMed was performed to identify articles published before December 2020. We included 18 studies with a total of n = 2,654 patients. While there is currently no consensus on research or clinical criteria for SCD in PD, this review presents the accumulated evidence for SCD in PD patients and supports the importance of early identification of cognitive deficits, due to the relatively high prevalence for SCD in PD and the added risk of future cognitive impairment it entails. The publications included in this review indicate that SCD may be part of the PD spectrum but further research is needed. Expanding research on SCD in PD will allow for earlier detection of cognitive impairment and may foster preventive interventions.

Validation of the Chinese version of Addenbrooke's cognitive examination III for detecting mild cognitive impairment

OBJECTIVES

To evaluate the reliability and validity of Chinese version of Addenbrooke's Cognitive Examination III (ACE-III-CV) in the identification of mild cognitive impairment (MCI), and further investigate the optimal cutoff scores according to different age and education level.

METHOD

A total of 716 individuals aged from 50 to 90 years old were recruited through internet-based and print advertisements, including 431 cognitively normal controls (NC) and 285 individuals with MCI according to an actuarial neuropsychological method put forward by Jak and Bondi. Besides the cognitive screening tests of ACE-III-CV, Mini-Mental State Examination (MMSE) and Chinese version of Montreal Cognitive Assessment-Basic (MoCA-BC), all the participants underwent a battery of standardized neuropsychological tests. Validations of the ACE-III-CV, MMSE, and MoCA-BC for detecting MCI from NC were determined by Receiver operating characteristic (ROC) curves.

RESULTS

ACE-III-CV had a good reliability (Cronbach's coefficient α = 0.807, intraclass correlation coefficients for interrater and test-retest reliability were 0.95 and 0.93). According to the area under ROC curve (AUC), ACE-III-CV and MoCA-BC showed better ability than MMSE in detecting MCI. No significant difference was found between ACE-III-CV and MoCA-BC. The optimal cutoff scores of ACE-III-CV for screening MCI were 72 for individuals with 1-9 years of education, 78 for individuals with 10-15 years of education, and 80 for individuals with more than 16 years of education.

CONCLUSION

The Chinese version of ACE-III-CV is a reliable and valid screening tool for detecting MCI. The optimal cutoff scores are closely related with education level.

Self-Administered Gerocognitive Examination: longitudinal cohort testing for the early detection of dementia conversion

Background

Significant cognitive changes as individuals’ age are not being identified in a timely manner, delaying diagnosis and treatments. Use of brief, multi-domain, self-administered, objective cognitive assessment tools may remove some barriers in assessing and identifying cognitive changes. We compared longitudinal Self-Administered Gerocognitive Examination (SAGE) test scores to non-self-administered Mini-Mental State Examination (MMSE) scores in 5 different diagnostic subgroups.

Methods

A cohort study evaluating annual rates of change was performed on 665 consecutive patients from Ohio State University Memory Disorders Clinic. Patients with at least two visits 6 months apart evaluated with SAGE and MMSE and classified according to standard clinical criteria as subjective cognitive decline (SCD), mild cognitive impairment (MCI), or Alzheimer’s disease (AD) dementia were included. The pattern of change in SAGE scores was compared to MMSE. One way and repeated measures ANOVA and linear regression models were used.

Results

Four hundred twenty-four individuals (40 SCD, 94 MCI non-converters to dementia, 70 MCI converters to dementia (49 to AD dementia and 21 to non-AD dementia), 220 AD dementia) met inclusion criteria. SAGE and MMSE scores declined respectively at annual rates of 1.91 points/year (p < 0.0001) and 1.68 points/year (p < 0.0001) for MCI converters to AD dementia, and 1.82 points/year (p < 0.0001) and 2.38 points/year (p < 0.0001) for AD dementia subjects. SAGE and MMSE scores remained stable for SCD and MCI non-converters. Statistically significant decline from baseline scores in SAGE occurred at least 6 months earlier than MMSE for MCI converters to AD dementia (14.4 vs. 20.4 months), MCI converters to non-AD dementia (14.4 vs. 32.9 months), and AD dementia individuals (8.3 vs. 14.4 months).

Conclusions

SAGE detects MCI conversion to dementia at least 6 months sooner than MMSE. Being self-administered, SAGE also addresses a critical need of removing some barriers in performing cognitive assessments. Limitations of our single-site cohort study include potential referral and sampling biases. Repetitively administering SAGE and identifying stability or decline may provide clinicians with an objective cognitive biomarker impacting evaluation and management choices.

Psychedelics as Novel Therapeutics in Alzheimer's Disease: Rationale and Potential Mechanisms

Serotonin 2A receptor (5-HT_2AR) agonist "classic psychedelics" are drawing increasing interest as potential mental health treatments. Recent work suggests psychedelics can exert persisting anxiolytic and antidepressant effects lasting up to several months after a single administration. Data indicate acute subjective drug effects as important psychological factors involved in observed therapeutic benefits. Additionally, animal models have shown an important role for 5-HT_2AR agonists in modulating learning and memory function with relevance for Alzheimer's Disease (AD) and related dementias. A number of biological mechanisms of action are under investigation to elucidate 5-HT_2AR agonists' therapeutic potential, including enhanced neuroplasticity, anti-inflammatory effects, and alterations in brain functional connectivity. These diverse lines of research are reviewed here along with a discussion of AD pathophysiology and neuropsychiatric symptoms to highlight classic psychedelics as potential novel pharmacotherapies for patients with AD. Human clinical research suggests a possible role for high-dose psychedelic administration in symptomatic treatment of depressed mood and anxiety in early-stage AD. Preclinical data indicate a potential for low- or high-dose psychedelic treatment regimens to slow or reverse brain atrophy, enhance cognitive function, and slow progression of AD. In conclusion, rationale and potential approaches for preliminary research with psychedelics in patients with AD are presented, and ramifications of this line of investigation for development of novel AD treatments are discussed.

[Effects of occupational exposure to aluminum on verbal function of workers]

Objective: To explore the effect of occupational aluminum (Al) exposure on workers' overall cognitive level and speech function. Methods: In July 2019, by using cluster sampling method, the group of 232 exposed to Al from an Al plant in Shanxi Province were selected as the exposed group, and the group of 228 not exposed to Al were selected as the control group. The blood Al concentration was determined by inductively coupled plasma mass spectrometry (ICP-MAS) . The exposed group was divided into high exposure group and low exposure group according to the median (M) concentration of Al in serum. The general cognitive function and speech function were evaluated with the Montreal Cognitive Assessment Scale (MoCA) , and the differences in the general cognitive function and speech function between the groups were compared, and non-conditional logistic regression was used to analyze the possible influencing factors of mild cognitive impairment (MCI) . Results: There were significant differences in age, working age, education and drinking status between Al exposed group and control group (P<0.05) . The total MoCA score, animal naming tese (ANT) score and category fluency repetition (CFT) score in Al exposure group were lower than control group and the differences were statistically significant (P<0.05) . The full rate of ANT was lower than that of CFT in Al exposure group (P<0.05) . The total MoCA score, ANT score and CFT score in the high exposure group were significantly lower than those in the control group (P<0.05) . The score of MoCA, ANT and CFT in high exposure group were lower than those in low exposure group between the level of serum aluminum>60 μg/L group and ≤60 μg/L group (P<0.05) . Logistic regression analysis showed that working age, serun Al concentration, ANT score, CFT score and SR score were the possible influencing factors of MCI in occupational Al exposure workers (P<0.05) . Conclusion: Occupational Al exposure can lead to impaired speech function of workers, the higher the ANT score, CFT score and SR score, the lower working age and serum Al concentration, the lower risk of MCI.

Interindividual and intraindividual variability in amnestic mild cognitive impairment (aMCI) measured with an online cognitive assessment

INTRODUCTION

Mean cognitive performance is worse in amnestic mild cognitive impairment (aMCI) compared to control groups. However, studies on variability of cognitive performance in aMCI have yielded inconclusive results, with many differences in variability measures and samples from one study to another.

METHODS

We examined variability in aMCI using an existing older adult sample (n = 91; 51 with aMCI, 40 with normal cognition for age), measured with an online self-administered computerized cognitive assessment (Cogniciti's Brain Health Assessment). Our methodology extended past findings by using pure measures of variability (controlling for confounding effects of group performance or practice), and a clinically representative aMCI sample (reflecting the continuum of cognitive performance between normal cognition and aMCI).

RESULTS

Between-group t-tests showed significantly greater between-person variability (interindividual variability or diversity) in overall cognitive performance in aMCI than controls, although the effect size was with a small to moderate effect size, d = 0.44. No significant group differences were found in within-person variability (intraindividual variability) across cognitive tasks (dispersion) or across trials of a response time task (inconsistency), which may be because we used a sample measuring the continuum of cognitive performance. Exploratory correlation analyses showed that a worse overall score was associated with greater inter- and intraindividual variability, and that variability measures were correlated with each other, indicating people with worse cognitive performance were more variable.

DISCUSSION

The current study demonstrates that self-administered online tests can be used to remotely assess different types of variability in people at risk of Alzheimer`s. Our findings show small but significantly more interindividual differences in people with aMCI. This diversity is considered as "noise" in standard assessments of mean performance, but offers an interesting and cognitively informative "signal" in itself.

Association between handgrip strength and cognition in a Chinese population with Alzheimer's disease and mild cognitive impairment

Background

This study aimed to explore the level and changes in handgrip strength among preclinical Alzheimer’s disease (AD) and AD patients and to evaluate the association between handgrip strength and cognitive function.

Methods

A total of 1431 participants from the memory clinic of Shanghai JiaoTong University Affiliated Sixth People’s Hospital and community were enrolled in the final analysis, including 596 AD, 288 mild cognitive impairment (MCI), and 547 normal individuals (NC). All participants received a comprehensive neuropsychological assessment. Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment-Basic (MoCA-BC), and the Chinese version of Addenbrooke’s Cognitive Examination III (ACE-III-CV) were used as cognitive tests. The receiver operating characteristic curve (ROC) was plotted to assess the power of handgrip strength as a screening measure to discriminate AD and MCI.

Results

The results showed that handgrip strength in the MCI group was significantly lower than that of NC group, and the AD group had a further decline (both P < 0.01). Multivariate logistic regression was performed with the handgrip strength quartiles, and the results showed that the ORs of AD for increasing levels of handgrip strength were 1.00, 0.58 (0.46–0.78), 0.51 (0.36–0.73), and 0.50 (0.35–0.68), showing a decreasing trend (P_{for trend} < 0.01). The ROC curve demonstrated that the handgrip strength cutoff points for the identification of AD were 16.8 and 20.7 kg among the female participants above and under 70 yrs and 24.4 and 33.3 kg for the male participants above and under 70 yrs, respectively. Similarly, for the identification of MCI, cutoff points were 17.5 and 21.9 kg for females above 70 yrs and under 70 yrs, and 25.8 and 36.2 kg for males above 70 yrs and under 70 yrs, respectively.

Conclusions

Our study provided the further knowledge on the relationship between noncognitive features and cognition in populations with differing cognitive status, revealed that the stronger handgrip strength was associated with better performances on cognitive function. It can be speculated that handgrip strength can help early recognition of Chinese AD patients.

Five-year outcomes after IVIG for mild cognitive impairment due to alzheimer disease

Background

The purpose of this study was to assess the five-year treatment effects of a short course of intravenous immunoglobulin (IVIG) in subjects with mild cognitive impairment (MCI) due to Alzheimer disease (AD).

Methods

Fifty subjects 50 to 84 years of age with MCI due to AD were administered 0.4 g/kg 10% IVIG or 0.9% saline every two weeks x five doses in a randomized double-blinded design as part of a two-year study. Twenty-seven subjects completed an additional three-year extension study. MRI brain imaging, cognitive testing, and conversion to dementia were assessed annually. Participants were stratified into early MCI (E-MCI) and late MCI (L-MCI). The primary endpoint was brain atrophy measured as annualized percent change in ventricular volume (APCV) annually for five years. ANOVA was used to compare annualized percent change in ventricular volume from baseline between the groups adjusting for MCI status (E-MCI, L-MCI).

Results

Differences in brain atrophy between the groups, which were statistically significant after one year, were no longer significant after five years. IVIG-treated L-MCI subjects did demonstrate a delay in conversion to dementia of 21.4 weeks.

Conclusion

An eight-week course of IVIG totaling 2 g/kg in MCI is safe but is not sufficient to sustain an initial reduction in brain atrophy or a temporary delay in conversion to dementia at five years. Other dosing strategies of IVIG in the early stages of AD should be investigated to assess more sustainable disease-modifying effects.

Trial registration ClinicalTrials.gov NCT01300728. Registered 23 February 2011.

Harnessing forgetfulness: can episodic-memory tests predict early Alzheimer's disease?

A rapid increase in the number of patients with Alzheimer's disease (AD) is expected over the next decades. Accordingly, there is a critical need for early-stage AD detection methods that can enable effective treatment strategies. In this study, we consider the ability of episodic-memory measures to predict mild cognitive impairment (MCI) to AD conversion and thus, detect early-stage AD. For our analysis, we studied 307 participants with MCI across four years using data from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Using a binary logistic regression, we compared episodic-memory tests to each other and to prominent neuroimaging methods in MCI converter (MCI participants who developed AD) and MCI non-converter groups (MCI participants who did not develop AD). We also combined variables to test the accuracy of mixed-predictor models. Our results indicated that the best predictors of MCI to AD conversion were the following: a combined episodic-memory and neuroimaging model in year one (59.8%), the Rey Auditory Verbal Learning Test in year two (71.7%), a mixed episodic-memory predictor model in year three (77.7%) and the Logical Memory Test in year four (77.2%) of ADNI. Overall, we found that individual episodic-memory measure and mixed models performed similarly when predicting MCI to AD conversion. Comparatively, individual neuroimaging measures predicted MCI conversion worse than chance. Accordingly, our results indicate that episodic-memory tests could be instrumental in detecting early-stage AD and enabling effective treatment.

Aberrant cerebral perfusion pattern in amnestic mild cognitive impairment and Parkinson's disease with mild cognitive impairment: a comparative arterial spin labeling study

Background

Mild cognitive impairment (MCI) has been defined as the prodromal stage of Alzheimer's disease and Parkinson's disease (PD) with dementia. We investigated the differences in regional perfusion properties among MCI subtypes and healthy control (HC) subjects by using arterial spin labeling (ASL).

Methods

Regional normalized CBF (z-CBF) and CBF-connectivity were analyzed from ASL data in 44 amnestic MCI (aMCI) patients, 42 PD-MCI patients, and 50 matched HC participants. The correlations between these significant regions and clinical performance were investigated separately using Spearman correlation analysis. Receiver operating characteristic analysis was generated to determine the differentiating ability of z-CBF values. z-CBF values in disease-related specific regions were extracted for group comparison.

Results

MCI subgroups showed overlapped impaired regions, aMCI group seemed more extensive than the PD-MCI group. PD-MCI patients had reduced z-CBF in the bilateral putamen, left precentral gyrus, left middle cingulate gyrus, and right middle frontal gyrus compared to aMCI group. Correlations to executive performance and motor severity were found in PD-MCI group, and correlations were to memory performance found in aMCI group. CBF-connectivity in left precentral gyrus, left middle cingulate gyrus, and right middle frontal gyrus were significantly altered. All of the significant clusters had good discriminatory ability.

Conclusions

Normalized CBF as measured by ASL revealed different patterns of perfusion between aMCI and PD-MCI, which were probably linked to distinct neural mechanisms. The present study indicates that z-CBF can provide specific perfusion information for further pathological and neuropsychological studies.

THAN: task-driven hierarchical attention network for the diagnosis of mild cognitive impairment and Alzheimer's disease

BACKGROUND

To assist doctors to diagnose mild cognitive impairment (MCI) and Alzheimer's disease (AD) early and accurately, convolutional neural networks based on structural magnetic resonance imaging (sMRI) images have been developed and shown excellent performance. However, they are still limited in their capacity in extracting discriminative features because of large sMRI image volumes yet small lesion regions and the small number of sMRI images.

METHODS

We proposed a task-driven hierarchical attention network (THAN) taking advantage of the merits of patch-based and attention-based convolutional neural networks for MCI and AD diagnosis. THAN consists of an information sub-network and a hierarchical attention sub-network. In the information sub-network, an information map extractor, a patch-assistant module, and a mutual-boosting loss function are designed to generate a task-driven information map, which automatically highlights disease-related regions and their importance for final classification. In the hierarchical attention sub-network, a visual attention module and a semantic attention module are devised based on the information map to extract discriminative features for disease diagnosis.

RESULTS

Extensive experiments were conducted for four classification tasks: MCI versus (vs.) normal controls (NC), AD vs. NC, AD vs. MCI, and AD vs. MCI vs. NC. Results demonstrated that THAN attained the accuracy of 81.6% for MCI vs. NC, 93.5% for AD vs. NC, 80.8% for AD vs. MCI, and 62.9% for AD vs. MCI vs. NC. It outperformed advanced attention-based and patch-based methods. Moreover, information maps generated by the information sub-network could highlight the potential biomarkers of MCI and AD, such as the hippocampus and ventricles. Furthermore, when the visual and semantic attention modules were combined, the performance of the four tasks was highly improved.

CONCLUSIONS

The information sub-network can automatically highlight the disease-related regions. The hierarchical attention sub-network can extract discriminative visual and semantic features. Through the two sub-networks, THAN fully exploits the visual and semantic features of disease-related regions and meanwhile considers global features of sMRI images, which finally facilitate the diagnosis of MCI and AD.

Diagnostic and Prognostic Laboratory Testing for Alzheimer Disease

This article focuses on current clinical laboratory testing to diagnose Alzheimer disease and monitor its progression throughout its disease course. Several clinically available tests focus on analysis of amyloid and tau levels in cerebrospinal fluid as well as autosomal dominant and risk factor genes. Although the current armament of clinical laboratory testing is limited by invasiveness of cerebrospinal fluid collection, rarity of autosomal dominant genetic mutations, and uncertainties of risk inherent in nonpenetrant genes, the field is poised to advance the clinical repertoire of laboratory diagnostic testing.

Identifying and characterizing different stages toward Alzheimer's disease using ordered core features and machine learning

Based on the joint HCPMMP parcellation method we developed before, which divides the cortical brain into 360 regions, the concept of ordered core features (OCF) is first proposed to reveal the functional brain connectivity relationship among different cohorts of Alzheimer's disease (AD), late mild cognitive impairment (LMCI), early mild cognitive impairment (EMCI) and healthy controls (HC). A set of core network features that change significantly under the specifically progressive relationship were extracted and used as supervised machine learning classifiers. The network nodes in this set mainly locate in the frontal lobe and insular, forming a narrow band, which are responsible for cognitive impairment as suggested by previous finding. By using these features, the accuracy ranged from 86.0% to 95.5% in binary classification between any pair of cohorts, higher than 70.1%-91.0% when using all network features. In multi-group classification, the average accuracy was 75% or 78% for HC, EMCI, LMCI or EMCI, LMCI, AD against baseline of 33%, and 53.3% for HC, EMCI, LMCI and AD against baseline of 25%. In addition, the recognition rate was lower when combining EMCI and LMCI patients into one group of mild cognitive impairment (MCI) for classification, suggesting that there exists a big difference between early and late MCI patients. This finding supports the EMCI/LMCI inclusion criteria introduced by ADNI based on neuropsychological assessments.

Diagnosis of Mild Cognitive Impairment Using Cognitive Tasks: A Functional Near-Infrared Spectroscopy Study

BACKGROUND

Early diagnosis of Alzheimer's disease (AD) is essential in preventing its progression to dementia. Mild cognitive impairment (MCI) can be indicative of early-stage AD. In this study, we propose a channel-wise feature extraction method of functional near-infrared spectroscopy (fNIRS) data to diagnose MCI when performing cognitive tasks, including two-back, Stroop, and semantic verbal fluency tasks (SVFT).

METHODS

A new channel-wise feature extraction method is proposed as follows: A region-of-interest (ROI) channel is defined as such channel having a statistical difference (p < 0.05) in t-values between two groups. For each ROI channel, features (the mean, slope, skewness, kurtosis, and peak value of oxy- and deoxy-hemoglobin) are extracted. The extracted features for the two classes (MCI, HC) are classified using the linear discriminant analysis (LDA) and support vector machine (SVM). Finally, the classifiers are validated using the area under curve (AUC) of the receiver operating characteristics. Furthermore, the suggested feature extraction method is compared with the conventional approach. Fifteen MCI patients and fifteen healthy controls (HCs) participated in the study.

RESULTS

In the two-back and Stroop tasks, HCs showed activation in the ventrolateral prefrontal cortex (VLPFC). However, in the case of MCI, the VLPFC was not activated. Instead, Ch. 30 was activated. In the SVFT task, the PFC was activated in both groups, but the t-values of HCs were higher than those of MCI. For the SVFT, the classification accuracies using the proposed feature extraction method were 80.77% (LDA) and 83.33% (SVM), showing the highest among the three tasks; for the Stroop task, 79.49% (LDA) and 73.08% (SVM); and for the two-back task, 73.08% (LDA) and 69.23% (SVM).

CONCLUSION

The cognitive disparities between the MCI and HC groups were detected in the ventrolateral prefrontal cortex using fNIRS. The proposed feature extraction method has shown an improvement in the classification accuracies, see Subsection 3.3. Most of all, the suggested method contains a groupdistinction information per cognitive task. The obtained results successfully discriminated MCI patients from HCs, which reflects that the proposed method is an efficient tool to extract features in fNIRS signals.

Cuneus/precuneus as a central hub for brain functional connectivity of mild cognitive impairment in idiopathic REM sleep behavior patients

PURPOSE

To investigate brain functional correlates of mild cognitive impairment (MCI) in idiopathic REM sleep behavior disorder (iRBD).

METHODS

Thirty-nine consecutive iRBD patients, 17 with (RBD-MCI, 73.6±6.5 years), and 22 without (RBD-NC, 69.6±6.1 years) MCI underwent neuropsychological assessment, ¹⁸F-FDG-PET, and ¹²³I-FP-CIT-SPECT as a marker of nigro-striatal dopaminergic function. Forty-two healthy subjects (69.6±8.5 years) were used as control for ¹⁸F-FDG-PET analysis. Brain metabolism was compared between the three groups by univariate analysis of variance. Post hoc comparison between RBD-MCI and RBD-NC was performed to investigate the presence of an MCI-related volume of interest (MCI-VOI). Brain functional connectivity was explored by interregional correlation analysis (IRCA), using the whole-brain normalized MCI-VOI uptake as the independent variable. Moreover, the MCI-VOI uptake was correlated with ¹²³I-FP-CIT-SPECT specific-to-non displaceable binding ratios (SBR) and neuropsychological variables. Finally, the MCI-VOI white matter structural connectivity was analyzed by using a MRI-derived human atlas.

RESULTS

The MCI-VOI was characterized by a relative hypometabolism involving precuneus and cuneus (height threshold p<0.0001). IRCA (height threshold p<0.0001) revealed a brain functional network involving regions in frontal, temporal, parietal, and occipital lobes, thalamus, caudate, and red nuclei in iRBD patients. In controls, the network was smaller and involved temporal, occipital, cingulate cortex, and cerebellum. Moreover, MCI-VOI metabolism was correlated with verbal memory (p=0.01), executive functions (p=0.0001), and nigro-putaminal SBR (p=0.005). Finally, MCI-VOI was involved in a white matter network including cingulate fasciculus and corpus callosum.

CONCLUSION

Our data suggest that cuneus/precuneus is a hub of a large functional network subserving cognitive function in iRBD.