Camila Vieira Ligo Teixeira

Differences and the Relationship in Default Mode Network Intrinsic Activity and Functional Connectivity in Mild Alzheimer's Disease and Amnestic Mild Cognitive Impairment

There is evidence that the default mode network (DMN) functional connectivity is impaired in Alzheimers disease (AD) and few studies also reported a decrease in DMN intrinsic activity, measured by the amplitude of low-frequency fluctuations (ALFFs). In this study, we analyzed the relationship between DMN intrinsic activity and functional connectivity, as well as their possible implications on cognition in patients with mild AD and amnestic mild cognitive impairment (aMCI) and healthy controls. In addition, we evaluated the differences both in connectivity and ALFF values between these groups. We recruited 29 controls, 20 aMCI, and 32 mild AD patients. To identify the DMN, functional connectivity was calculated by placing a seed in the posterior cingulate cortex (PCC). Within the DMN mask obtained, we calculated regional average ALFFs. Compared with controls, aMCI patients showed decreased ALFFs in the temporal region; compared with AD, aMCI showed higher values in the PCC but lower in the temporal area. The mild AD group had lower ALFFs in the PCC compared with controls. There was no difference between the connectivity in the aMCI group compared with the other groups, but AD patients showed decreased connectivity in the frontal, parietal, and PCC. Also, PCC ALFFs correlated to functional connectivity in nearly all subregions. Cognitive tests correlated to connectivity values but not to ALFFs. In conclusion, we found that DMN connectivity and ALFFs are correlated in these groups. Decreased PCC ALFFs disrupt the DMN functional organization, leading to cognitive problems in the AD spectrum.

Intranetwork and internetwork connectivity in patients with Alzheimer disease and the association with cerebrospinal fluid biomarker levels

Background In the last decade, many studies have reported abnormal connectivity within the default mode network (DMN) in patients with Alzheimer disease. Few studies, however, have investigated other networks and their association with pathophysiological proteins obtained from cerebrospinal fluid (CSF). Methods We performed 3 T imaging in patients with mild Alzheimer disease, patients with amnestic mild cognitive impairment (aMCI) and healthy controls, and we collected CSF samples from the patients with aMCI and mild Alzheimer disease. We analyzed 57 regions from 8 networks. Additionally, we performed correlation tests to investigate possible associations between the networks’ functional connectivity and the protein levels obtained from the CSF of patients with aMCI and Alzheimer disease. Results Our sample included 41 patients with Alzheimer disease, 35 with aMCI and 48 controls. We found that the main connectivity abnormalities in those with Alzheimer disease occurred between the DMN and task-positive networks: these patients presented not only a decreased anticorrelation between some regions, but also an inversion of the correlation signal (positive correlation instead of anti-correlation). Those with aMCI did not present statistically different connectivity from patients with Alzheimer disease or controls. Abnormal levels of CSF proteins were associated with functional disconnectivity between several regions in both the aMCI and mild Alzheimer disease groups, extending well beyond the DMN or temporal areas. Limitations The presented data are cross-sectional in nature, and our findings are dependent on the choice of seed regions used. Conclusion We found that the main functional connectivity abnormalities occur between the DMN and task-positive networks and that the pathological levels of CSF biomarkers correlate with functional connectivity disruption in patients with Alzheimer disease.

Cognitive Reserve Relates to Functional Network Efficiency in Alzheimer’s Disease

Alzheimer’s disease (AD) is the most common form of dementia, with no means of cure or prevention. The presence of abnormal disease-related proteins in the population is, in turn, much more common than the incidence of dementia. In this context, the cognitive reserve (CR) hypothesis has been proposed to explain the discontinuity between pathophysiological and clinical expression of AD, suggesting that CR mitigates the effects of pathology on clinical expression and cognition. fMRI studies of the human connectome have recently reported that AD patients present diminished functional efficiency in resting-state networks, leading to a loss in information flow and cognitive processing. No study has investigated, however, whether CR modifies the effects of the pathology in functional network efficiency in AD patients. We analyzed the relationship between CR, pathophysiology and network efficiency, and whether CR modifies the relationship between them. Fourteen mild AD, 28 amnestic mild cognitive impairment (aMCI) due to AD, and 28 controls were enrolled. We used education to measure CR, cerebrospinal fluid (CSF) biomarkers to evaluate pathophysiology, and graph metrics to measure network efficiency. We found no relationship between CR and CSF biomarkers; CR was related to higher network efficiency in all groups; and abnormal levels of CSF protein biomarkers were related to more efficient networks in the AD group. Education modified the effects of tau-related pathology in the aMCI and mild AD groups. Although higher CR might not protect individuals from developing AD pathophysiology, AD patients with higher CR are better able to cope with the effects of pathology—presenting more efficient networks despite pathology burden. The present study highlights that interventions focusing on cognitive stimulation might be useful to slow age-related cognitive decline or dementia and lengthen healthy aging.

Cognitive and structural cerebral changes in amnestic mild cognitive impairment due to Alzheimer's disease after multicomponent training

Information about how physical exercise affects patients with amnestic mild cognitive impairment (aMCI) due to Alzheimers disease (AD) is still missing. This study evaluated the impact of multicomponent exercise training on cognition and brain structure in aMCI subjects with cerebral spinal fluid positive AD biomarkers.

ALZHEIMER’S DISEASE PATIENTS WITH HIGHER COGNITIVE RESERVE PRESENT MORE EFFICIENT NETWORK TOPOLOGY

represent statistically significant enriched gene sets (red 1⁄4 upregulated, blue 1⁄4 down-regulated) grouped and annotated by their similarity. The edges (links) show the degree of gene set overlap. Node size is proportional to the total number of genes in each gene set. The edge thickness represents the number of overlapping genes between gene sets. Gene sets are linked if their combined overlap coefficient is > 0.5. Podium Presentations: Monday, July 17, 2017 P584

EFFECTS OF AEROBIC EXERCISE ON PROGRESSION OF HIPPOCAMPAL VOLUME AND COGNITION IN AMNESTIC MILD COGNITIVE IMPAIRMENT DUE TO AD

anosognosia; sixteen had anosognosia for memory items, fifteen showed anosognosia for non-memory items, and ten had anosognosia for both memory and non-memory items. Pearson’s correlations showed that the total discrepancy and non-memory scores were significantly correlated with a measure of global cognitive ability (the Mini-Mental State Examination), abstract reasoning (Raven’s Progressive Matrices), constructional apraxia (i.e., Rey-Osterrieth Figure – copy) and short-term memory (Digit Span and Corsi block-tapping test). Lower GM volume in fronto-limbic areas (i.e., the anterior cingulate and medial frontal gyrus) was also found to be associated with reduced general awareness. The memory subcomponent discrepancy scores only correlated with short-term memory and global cognitive ability, and were associated with lower GM volume in fronto-limbic areas and in subcortical structures (i.e., thalamus, caudate). Conclusions:This study demonstrates that anosognosia of cognitive and functional performance in amnestic MCI patients is associated with general cognitive impairment, memory dysfunction and lower GM volume in fronto-limbic and subcortical structures. These results support recent evidence according to which these anatomical regions are involved in reduced awareness and confirm the importance to delineate and further explore anosognosia of both memory and non-memory dysfunctions.

Systemic inflammation is linked to default mode network functional connectivity in mild alzheimer's disease and mild cognitive impairment

The desriptive statistics, limitation, strenghts especially in primaty care units be discussed. Results: The database was initiated in May 2007 and covers almost all of Sweden. There were 50 000 patients registered during 2007– 2014. The role of primary care units increased in that time and helped for diagnosis of new cases. Conclusion: SveDem provides knowledge about current dementia care in Sweden and serves as a framework for ensuring the quality of diagnostics, treatment and care across the country. The special role of primary care in dementia work up is important.