scholarly journals Decreased Dynamic Flexibility of Brain Functional Connectivity in Prodromal Alzheimer’s Disease

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Zachary G. Osborn ◽  
Shannon L. Risacher ◽  
John D. West ◽  
Eileen Tallman ◽  
Liana Apostolova ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Connectivity ◽  
Cognitive Decline ◽  
Functional Mri ◽  
Information Transfer ◽  
Time Windows ◽  
Parahippocampal Gyrus ◽  
Subjective Cognitive Decline ◽  
Functional Flexibility

Background and Hypothesis:  In neuroimaging, functional connectivity (FC), defined as the correlation between the functional MRI signals of two brain grey matter regions of interest (ROIs), is thought to reflect communication between ROIs. Changes in whole brain FC networks have been detected in Alzheimer’s disease (AD); however, traditional FC networks generated using the entire length of an fMRI scan could miss cognitively relevant fluctuations in FC. Analyzing dynamic patterns of FC within subsets of fMRI scans is hypothesized to enable greater sensitivity to deficits of information transfer and processing in AD compared to static FC.  Project Methods:  Functional MRI data of 58 participants with either subjective cognitive decline (SCD), mild cognitive impairment (MCI), AD, or controls were divided into time windows; the FC within each window provides sequential dynamic FC networks (dFC). Each dFC network was partitioned into subnetworks, e.g. visual or motor, whose member ROIs are strongly interconnected, and the functional flexibility of an ROI was estimated by the number of times it switches subnetworks in a scan.  Results:  The flexibility of the left inferior parietal lobule, right rostral lateral orbitofrontal cortex, and right amyglada/parahippocampal gyrus showed the highest correlations with Montreal Cognitive Assessment scores: r = 0.2516, 0.2480, and 2421, respectively. Although no correlations reached conventional significance (p = 0.0568, 0.0605, and 0.0671, uncorrected), this may reflect low power that should be increased with a planned larger sample.  Potential Impact:  Dynamic FC analyses may help clarify the neurophysiological mechanisms underlying cognitive decline, but methodological refinements and higher resolution data are likely needed to realize this potential.

Identification of Earlier Biomarkers for Alzheimer’s Disease: A Multimodal Neuroimaging Study of Individuals with Subjective Cognitive Decline

2020 ◽  
Vol 77 (3) ◽  
pp. 1067-1076
Author(s):  
Ashleigh F. Parker ◽  
Colette M. Smart ◽  
Vanessa Scarapicchia ◽  
Jodie R. Gawryluk ◽  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Connectivity ◽  
Cognitive Decline ◽  
Functional Mri ◽  
Healthy Aging ◽  
Angular Gyrus ◽  
Subjective Cognitive Decline ◽  
Grey Matter Volume ◽  
Increased Risk

Background: Individuals with subjective cognitive decline (SCD) are thought to be the earliest along the cognitive continuum between healthy aging and Alzheimer’s disease (AD). Objective: The current study used a multi-modal neuroimaging approach to examine differences in brain structure and function between individuals with SCD and healthy controls (HC). Methods: 3T high-resolution anatomical images and resting-state functional MRI scans were retrieved for 23 individuals with SCD and 23 HC from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. Results: The SCD and HC groups were not significantly different in age or education level. Voxel-based morphometry results did not show significant differences in grey matter volume between the groups. Functional MRI results revealed significantly greater functional connectivity in the default mode network in regions including the bilateral precuneus cortex, bilateral thalamus, and right hippocampal regions in individuals with SCD relative to controls. Conversely, those with SCD showed decreased functional connectivity in the bilateral frontal pole, caudate, angular gyrus, and lingual gyrus, compared to HC. Conclusion: Findings revealed differences in brain function but not structure between individuals with SCD and HC. Overall, this study represents a crucial step in characterizing individuals with SCD, a group recognized to be at increased risk for AD. It is imperative to identify biomarkers of AD prior to significant decline on clinical assessment, so that disease-delaying interventions may be delivered at the earliest possible time point.

scholarly journals Exploring dynamic functional connectivity alterations in the preclinical stage of Alzheimer’s disease: an exploratory study from SICOLDE

2021 ◽  
Author(s):  
Fan Yang ◽  
Xueyan Jiang ◽  
Feng Yue ◽  
Luyao Wang ◽  
Boecker Henning ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Connectivity ◽  
Cognitive Decline ◽  
Standardized Uptake Value ◽  
Magnetic Resonance Images ◽  
Subjective Cognitive Decline ◽  
Dynamic Functional Connectivity ◽  
Preclinical Stage ◽  
Neuropsychological Assessments

Abstract IntroductionExploring functional connectivity (FC) alterations is important for the understanding of underlying neuronal network alterations in subjective cognitive decline (SCD). The objective of this study was to discover stable and subtle dynamic functional connectivity (FC) changes in the preclinical stage of Alzheimer’s disease (AD), and to explore the associations between dynamic FCs and amyloid accumulation.MethodsNinety-seven normal control (NC) subjects, 101 subjective cognitive decline (SCD) subjects, and 55 cognitive impairment (CI) subjects with neuropsychological assessments and resting-state functional magnetic resonance images constituted the whole cohort. Of these, 29 NCs and 52 SCDs with amyloid images were selected as the sub-cohort. First, independent components (ICs) identified by group independent component analysis (ICA) were used to define static and dynamic brain networks. Static and sliding-window dynamic FCs were then calculated. Second, the connection between each pair of ICs was compared between groups in the two cohorts. Hubs were obtained and considered as seeds in the subsequent seed-based dynamic FC analysis. One-way analysis of variance (ANOVA) was used to compare the seed-based dynamic FC maps between groups in the whole cohort, while a 2×2 ANOVA model was used to measure the group or amyloid effects in the sub-cohort. Post-hoc analysis was applied, and differences were considered significant if the cluster-level FWE-corrected p-value was less than 0.001. Finally, correlation analysis was conducted between the altered dynamic FCs, neuropsychological assessments, and amyloid burden.ResultsThe results showed that 42 ICs were revealed. Compared with the static FCs, the dynamic FCs were found to be more stable and sensitive between groups. The effective dynamic FCs included those between the salience/ventral attention network, the default mode network, and the visual network. Specifically, the dynamic FC of the thalamus/caudate (IC 25) drove the hub role in the group differences between the NC and SCD groups. In the seed-based dynamic FC analysis, the dynamic FC between the thalamus/caudate and the middle temporal/frontal gyrus was observed to be higher in the SCD and CI groups in the whole cohort. Moreover, a higher dynamic FC between the thalamus/caudate and visual cortex was observed in the amyloid positive group. Finally, the altered dynamic FC was associated with the amyloid global level standardized uptake value ratio.ConclusionOur findings indicate that dynamic FCs can reflect subtle changes in the preclinical stage of AD.

Subjective Spatial Navigation Complaints - A Frequent Symptom Reported by Patients with Subjective Cognitive Decline, Mild Cognitive Impairment and Alzheimer's Disease

2018 ◽  
Vol 15 (3) ◽  
pp. 219-228 ◽  
Author(s):  
Jiri Cerman ◽  
Ross Andel ◽  
Jan Laczo ◽  
Martin Vyhnalek ◽  
Zuzana Nedelska ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Spatial Navigation ◽  
Subjective Cognitive Decline ◽  
Great Effort ◽  
Frequent Symptom ◽  
Normal Controls

Background: Great effort has been put into developing simple and feasible tools capable to detect Alzheimer's disease (AD) in its early clinical stage. Spatial navigation impairment occurs very early in AD and is detectable even in the stage of mild cognitive impairment (MCI). Objective: The aim was to describe the frequency of self-reported spatial navigation complaints in patients with subjective cognitive decline (SCD), amnestic and non-amnestic MCI (aMCI, naMCI) and AD dementia and to assess whether a simple questionnaire based on these complaints may be used to detect early AD. Method: In total 184 subjects: patients with aMCI (n=61), naMCI (n=27), SCD (n=63), dementia due to AD (n=20) and normal controls (n=13) were recruited. The subjects underwent neuropsychological examination and were administered a questionnaire addressing spatial navigation complaints. Responses to the 15 items questionnaire were scaled into four categories (no, minor, moderate and major complaints). Results: 55% of patients with aMCI, 64% with naMCI, 68% with SCD and 72% with AD complained about their spatial navigation. 38-61% of these complaints were moderate or major. Only 33% normal controls expressed complaints and none was ranked as moderate or major. The SCD, aMCI and AD dementia patients were more likely to express complaints than normal controls (p's<0.050) after adjusting for age, education, sex, depressive symptoms (OR for SCD=4.00, aMCI=3.90, AD dementia=7.02) or anxiety (OR for SCD=3.59, aMCI=3.64, AD dementia=6.41). Conclusion: Spatial navigation complaints are a frequent symptom not only in AD, but also in SCD and aMCI and can potentially be detected by a simple and inexpensive questionnaire.

scholarly journals Assessing visuo-constructive functions in patients with subjective cognitive decline, mild cognitive impairment and Alzheimer’s disease with the Vienna Visuo-Constructional Test 3.0 (VVT 3.0)

2021 ◽  
Author(s):  
Noel Valencia ◽  
Johann Lehrner
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Multinomial Logistic Regression ◽  
Subjective Cognitive Decline ◽  
Healthy Controls ◽  
Considerable Potential ◽  
Multinomial Logistic Regression Analysis

Summary Background Visuo-Constructive functions have considerable potential for the early diagnosis and monitoring of disease progression in Alzheimer’s disease. Objectives Using the Vienna Visuo-Constructional Test 3.0 (VVT 3.0), we measured visuo-constructive functions in subjective cognitive decline (SCD), mild cognitive impairment (MCI), Alzheimer’s disease (AD), and healthy controls to determine whether VVT performance can be used to distinguish these groups. Materials and methods Data of 671 participants was analyzed comparing scores across diagnostic groups and exploring associations with relevant clinical variables. Predictive validity was assessed using Receiver Operator Characteristic curves and multinomial logistic regression analysis. Results We found significant differences between AD and the other groups. Identification of cases suffering from visuo-constructive impairment was possible using VVT scores, but these did not permit classification into diagnostic subgroups. Conclusions In summary, VVT scores are useful indicators for visuo-constructive impairment but face challenges when attempting to discriminate between several diagnostic groups.

Subjective Cognitive Decline and its Relation to Verbal Memory and Sex in Cognitively Unimpaired Individuals from a Colombian Cohort with Autosomal-Dominant Alzheimer’s Disease

2021 ◽  
pp. 1-9
Author(s):  
Jairo E. Martinez ◽  
Enmanuelle Pardilla-Delgado ◽  
Edmarie Guzmán-Vélez ◽  
Clara Vila-Castelar ◽  
Rebecca Amariglio ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sex Differences ◽  
Cognitive Decline ◽  
Verbal Memory ◽  
Autosomal Dominant ◽  
Memory Performance ◽  
Subjective Cognitive Decline ◽  
Mutation Carriers ◽  
Study Partner

Abstract Objective: Subjective Cognitive Decline (SCD) may be an early indicator of risk for Alzheimer’s disease (AD). Findings regarding sex differences in SCD are inconsistent. Studying sex differences in SCD within cognitively unimpaired individuals with autosomal-dominant AD (ADAD), who will develop dementia, may inform sex-related SCD variations in preclinical AD. We examined sex differences in SCD within cognitively unimpaired mutation carriers from the world’s largest ADAD kindred and sex differences in the relationship between SCD and memory performance. Methods: We included 310 cognitively unimpaired Presenilin-1 (PSEN-1) E280A mutation carriers (51% females) and 1998 noncarrier family members (56% females) in the study. Subjects and their study partners completed SCD questionnaires and the CERAD word list delayed recall test. ANCOVAs were conducted to examine group differences in SCD, sex, and memory performance. In carriers, partial correlations were used to examine associations between SCD and memory performance covarying for education. Results: Females in both groups had greater self-reported and study partner-reported SCD than males (all p < 0.001). In female mutation carriers, greater self-reported (p = 0.02) and study partner-reported SCD (p < 0.001) were associated with worse verbal memory. In male mutation carriers, greater self-reported (p = 0.03), but not study partner-reported SCD (p = 0.11) was associated with worse verbal memory. Conclusions: Study partner-reported SCD may be a stronger indicator of memory decline in females versus males in individuals at risk for developing dementia. Future studies with independent samples and preclinical trials should consider sex differences when recruiting based on SCD criteria.

scholarly journals Promoting Conversations About Cognitive Decline Between Older Adults and Primary Care Providers

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 157-158
Author(s):  
Benjamin Olivari ◽  
Christopher Taylor ◽  
Nia Reed ◽  
Lisa McGuire
Keyword(s):  
Alzheimer’S Disease ◽  
Primary Care ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Cognitive Decline ◽  
Chronic Conditions ◽  
Memory Loss ◽  
Primary Care Providers ◽  
Subjective Cognitive Decline ◽  
Care Providers

Abstract Alzheimer’s disease and related dementias often begin with symptoms of mild memory loss, eventually leading to more severe cognitive impairment, functional impairment, and ultimately, death. Data from the Behavioral Risk Factor Surveillance System core questions related to chronic diseases and from the cognitive decline optional module on subjective cognitive decline (SCD) from the years 2015-2018 were aggregated across the participating 50 states, D.C., and Puerto Rico for this analysis. Among U.S. adults aged 65 years and older, only 39.8% (95%CI=37.6-42.1) of those experiencing SCD reported discussing their SCD symptoms with a healthcare provider. The prevalence of discussing SCD symptoms with a provider was higher among those with at least one chronic condition than among those with no chronic conditions. 30.7% (28.6-32.8) of those aged 65 years and older reported that their SCD led to functional limitations and 28.8% (26.5-31.2) needed assistance with day-to-day activities. For patients aged 65 years and older, Welcome to Medicare visits and Medicare Annual Wellness Visits are critically underutilized primary care access points. Primary care providers can manage chronic conditions, cognitive health, and initiate referrals for testing. Efforts to promote the use of toolkits and diagnostic codes that are available to primary care providers to initiate conversations about memory loss with patients may be utilized to improve detection, diagnosis, and planning for memory problems. Discussions may lead to earlier detection and diagnosis of cognitive impairment, such as Alzheimer’s disease, or other treatable conditions such as delirium or pressure in the brain and avoid costly hospitalizations.

Alexithymia in people with subjective cognitive decline, mild cognitive impairment, and mild Alzheimer’s disease

2017 ◽  
Vol 29 (6) ◽  
pp. 1105-1111 ◽  
Author(s):  
Mehmet Yuruyen ◽  
Fundan Engin Akcan ◽  
Gizem Cetiner Batun ◽  
Gozde Gultekin ◽  
Mesut Toprak ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Subjective Cognitive Decline

scholarly journals Subjective cognitive decline: The first clinical manifestation of Alzheimer's disease?

2016 ◽  
Vol 10 (3) ◽  
pp. 170-177 ◽  
Author(s):  
Adalberto Studart Neto ◽  
Ricardo Nitrini
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Clinical Manifestation ◽  
Neurodegenerative Disorder ◽  
Subjective Cognitive Decline ◽  
Subjective Memory ◽  
Increased Risk

ABSTRACT Background: Mild cognitive impairment is considered as the first clinical manifestation of Alzheimer's disease (AD), when the individual exhibits below performance on standardized neuropsychological tests. However, some subjects before having a lower performance on cognitive assessments already have a subjective memory complaint. Objective: A review about subjective cognitive decline, the association with AD biomarkers and risk of conversion to dementia. Methods: We performed a comprehensive non-systematic review on PubMed. The keywords used in the search were terms related to subjective cognitive decline. Results: Subjective cognitive decline is characterized by self-experience of deterioration in cognitive performance not detected objectively through formal neuropsychological testing. However, various terms and definitions have been used in the literature and the lack of a widely accepted concept hampers comparison of studies. Epidemiological data have shown that individuals with subjective cognitive decline are at increased risk of progression to AD dementia. In addition, there is evidence that this group has a higher prevalence of positive biomarkers for amyloidosis and neurodegeneration. However, Alzheimer's disease is not the only cause of subjective cognitive decline and various other conditions can be associated with subjective memory complaints, such as psychiatric disorders or normal aging. The features suggestive of a neurodegenerative disorder are: onset of decline within the last five years, age at onset above 60 years, associated concerns about decline and confirmation by an informant. Conclusion: These findings support the idea that subjective cognitive complaints may be an early clinical marker that precedes mild cognitive impairment due to Alzheimer's disease.

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