Neuroimaging correlates of persistent fatigue in older adults: A secondary analysis from the Multidomain Alzheimer Preventive Trial (MAPT) trial.

OBJECTIVES: Fatigue has been suggested as a marker of biological aging. It seems plausible that this symptom might be associated with changes in brain health. The objective of this study was to examine the associations between persistent fatigue and neuroimaging correlates in a non-disease-specific population of community-dwelling older adults. METHODS: We performed a cross-sectional analysis using data from The Multidomain Alzheimer Preventive Trial (MAPT). We included 458 subjects. Persistent fatigue was defined as meeting exhaustion criterion of Fried frailty phenotype in two consecutive clinical visits six months apart between study baseline and one year. Brain imaging correlates, assessed by magnetic resonance imaging (MRI), were the outcomes. The associations between persistent fatigue and brain correlates were explored using mixed model linear regressions with random effect at the center level. RESULTS: The mean age of the participants was 74.8 ± 4 years old, and 63% of the subjects were women. Forty-seven participants (10%) exhibited a persistent fatigue profile. People with persistent fatigue were older compared to subjects without persistent fatigue (76.2 years ± 4.3 vs.74.7 ± 3.9 p = 0.009). Persistent fatigue was associated with higher white matter hyperintensity volume in the fully adjusted analysis. We did not find any cross-sectional association between persistent fatigue and sub-cortical volumes and global and regional cortical thickness. CONCLUSION: Persistent fatigue was cross-sectionnally associated with higher white matter hyperintensity volume in older adults. Further longitudinal studies, using an assessment tool specifically designed and validated for measuring fatigue, are needed to confirm our findings.

Sulcal morphology as cognitive decline predictor in older adults with memory complaints.

To determine whether sulcal morphology can predict changes in cognition, we investigated the relationship between width of 20 cerebral sulci and cognitive decline. Sulcal width was measured in T1-weighted MRI images at baseline in 433 adults aged ≥70 years with memory complaints from the MRI-Multidomain Alzheimer Preventive Trial study. Cognition was evaluated at baseline, 6, 12, 24, and 36 months of follow-up with a composite Z score. The composite score variations over time relative to the baseline sulcal width were assessed using linear mixed regression models. We observed a positive association between a greater decline in cognitive composite score and the width of the superior and the anterior inferior temporal sulci, and the cingulate anterior sulcus of the left hemisphere. Sulcal widening in the lateral temporal and the cingulate anterior areas might predict cognitive decline in individuals with memory complaints.

Biological and Neuroimaging Markers as Predictors of 5-Year Incident Frailty in Older Adults: A Secondary Analysis of the MAPT Study.

BACKGROUND: This study aims to investigate the predictive value of biological and neuroimaging markers to determine incident frailty among older people for a period of 5 years. METHODS: We included 1394 adults aged 70 years and older from the Multidomain Alzheimer Preventive Trial, who were not frail at baseline (according to Fried's criteria) and who had at least 1 post-baseline measurement of frailty. Participants who progressed to frailty during the 5-year follow-up were categorized as "incident frailty" and those who remained non-frail were categorized as "without frailty." The differences of baseline biochemical factors (25-hydroxyvitamin D, homocysteine, omega-3 index, C-reactive protein), other biological markers (Apolipoprotein E genotypes, amyloid-ß deposits), and neuroimaging data (gray matter volume, hippocampal volume, white matter hyperintensities) were compared between groups. Cox proportional hazard model was used to evaluate the associations between biomarkers and incident frailty. RESULTS: A total of 195 participants (14.0%) became frail over 5 years. Although 25-hydroxyvitamin D deficiency, homocysteine levels, low-grade inflammation (persistently increased C-reactive protein 3-10 mg/L), gray matter, and hippocampal volume were significantly associated with incident frailty in unadjusted models, these associations disappeared after adjustment for age, sex, and other confounders. Omega-3 index was the sole marker that presented a trend of association with incident frailty (hazard ratio: 0.92; 95% confidence interval: 0.83-1.01; p = .082). CONCLUSIONS: This study failed to identify biomarkers able to predict frailty incidence in community-dwelling older adults for a period of 5 years. Further longitudinal research with multiple measurements of biomarkers and frailty is needed to evaluate the long-term relationships between changes in biomarkers levels and frailty evolution.

Cross-sectional and prospective associations between cerebral cortical thickness and frailty in older adults.

BACKGROUND: Several neurodegenerative markers measured by magnetic resonance imaging (MRI) have shown to be related with frailty. While most studies have focused on surrogates of cerebral vascular damage such as increased white matter lesions, the associations between cortical atrophy and frailty were less often investigated. OBJECTIVES: To investigate the cross-sectional and prospective associations between cortical thickness and frailty evolution in older adults. METHODS: We enrolled 484 community-dwelling adults aged ≥70 years, participants from the Multidomain Alzheimer Preventive Trial (MAPT), with data on cerebral cortical thickness and frailty. Cortical thickness was acquired by MRI for whole-brain and regional cortices. Two function-specific regions of interest, i.e., mobility-related regions and Alzheimer's disease (AD) signature, were selected on the basis of previous studies. Frailty status was assessed by the Fried frailty phenotype (i.e., weakness, slowness, involuntary weight loss, fatigue and low physical activity level) at baseline, after 6 months and every year until the end of the 5-year follow-up. RESULTS: Older adults with higher global cortical thickness were less likely to be pre-frail and frail at baseline (adjusted OR: 0.13, 95% CI: 0.03-0.65, p = 0.013). In addition, higher cortical thickness in mobility-related and AD-signature regions were associated with lower likelihood of being pre-frail and frail. Similar associations were observed for having weakness and slowness. However, neither global nor region-specific cortical thickness showed prospective associations with future frailty onset. CONCLUSIONS: The global and regional cortical thickness cross-sectionally associated with frailty in older adults, but no prospective associations with incident frailty were found. The longitudinal relationship between cortical thickness and frailty evolution requires further investigation.

Prospective Associations Between Diffusion Tensor Imaging Parameters and Frailty in Older Adults.

BACKGROUND: Cross-sectional associations have been found between frail individuals and worse white matter (WM) integrity. However, the prospective association between WM integrity and frailty is still unclear. Our objectives were to measure associations between WM integrity using diffusion tensor imaging (DTI) and the 5-year worsening of frailty in community-dwelling older adults. DESIGN: Secondary analysis of the randomized controlled Multidomain Alzheimer Preventive Trial (MAPT). SETTING: Thirteen memory centers in France and Monaco between 2008 and 2011. PARTICIPANTS: Participants (mean age = 74.7 ± 3.9 years) with no dementia at baseline who had functional magnetic resonance imaging performed as part of the MAPT study (n = 227). MEASUREMENTS: Fractional anisotropy and mean diffusivity (MD), axial diffusivity (AxD), and radial diffusivity (RD) were acquired for 10 different brain regions. Frailty was assessed by the Fried frailty phenotype (score from 0 to 5, higher is worse) at up to seven time points for 5 years. Mixed effect ordinal logistic regression model was used to assess the prospective association between DTI parameters (independent variables) and frailty (dependent variable). All the analyses were adjusted for age, sex, baseline total intracranial volume, and the presence of one of the following cardiovascular risk factors (hypertension, diabetes, and/or hypercholesterolemia). RESULTS: A statistically significant association was found between the RD, AxD, and MD for different brain regions (anterior limb of internal capsule, external capsule, posterior corona radiata, posterior thalamic radiation, superior corona radiata, superior frontal occipital fasciculus, and superior longitudinal fasciculus) and worsening of frailty over 5 years after adjusting for multiple comparisons. CONCLUSIONS: This is the first study to show that WM integrity is associated with frailty in older adults. The mechanisms related to these results require further investigation. J Am Geriatr Soc 68:1050-1055, 2020.

Prospective associations between physical activity levels and white matter integrity in older adults: results from the MAPT study.

BACKGROUND: Higher levels of physical activity (PA) are known to be associated with better white matter integrity measured by diffusion tensor imaging (DTI) in older adults in cross-sectional studies. However, no studies have investigated the association between PA levels and the evolution of DTI parameters (fractional anisotropy and mean diffusivity). OBJECTIVES: To examine the cross-sectional associations between PA levels and DTI parameters, then to investigate the association between baseline PA levels and the evolution of DTI parameters in older adults. METHODS: Data on magnetic resonance imaging with DTI method from the Multidomain Alzheimer's Preventive Trial (MAPT) study were used; 228 participants had data on DTI measured at three time-points over five years. Fractional anisotropy and mean diffusivity were acquired for six different brain regions. RESULTS: No significant associations were found in the cross-sectional analyses. Only one association was found: compared with active individuals, a faster worsening in the mean diffusivity of the uncinate fasciculus region was found in inactive individuals (-5.0 × 10-6 (-9.5 × 10-5, 4.9 × 10-6)). CONCLUSIONS: In this study, we found that the condition of the uncinate fasciculus region may be susceptible to changes in PA levels in older adults. Longitudinal studies that assess fitness and PA using objective measurements (e.g. cardiorespiratory fitness and accelerometry) could shed some new light on this topic.

Prospective associations between white matter hyperintensities and lower extremity function.

OBJECTIVE: To evaluate the relationship of white matter hyperintensities (WMH) with decline in lower extremity function (LEF) over approximately 3 years in dementia-free older adults with memory complaints. METHODS: We obtained brain MRI data from 458 community-dwelling adults, aged 70 years or over, at baseline, and from 358 adults over an average follow-up of 963 days. We evaluated LEF using the Short Physical Performance Battery (SPPB). We related baseline WMH volumes and progression to SPPB scores over time, using mixed-effect linear regressions. For the secondary analyses, we categorized baseline WMH volume into quartiles, and dichotomized the WMH progression to compare fast and slow progression. RESULTS: Baseline WMH volume (ß = -0.017, 95% confidence interval [CI] -0.025 to -0.009), as well as WMH progression (ß = -0.002, 95% CI -0.003 to -0.001), significantly associated with a decline in SPPB performance in adjusted analyses. Compared with the lowest quartile of baseline WMH volume, the highest quartile associated with a decline in SPPB performance (ß = -0.301, 95% CI -0.558 to -0.044). Fast progression also associated with a decline in SPPB performance. We found clinically meaningful differences in the SPPB, with higher scores in participants with slow progression of WMH, at both 24 and 36 months. CONCLUSIONS: Baseline level and WMH progression associated with longitudinal decline in SPPB performance among older adults. We detected clinically meaningful differences in SPPB performance on comparing fast with slow progression of WMH, suggesting that speed of WMH progression is an important determinant of LEF during aging.

Improved cerebral microbleeds detection using their magnetic signature on T2*-phase-contrast: A comparison study in a clinical setting.

INTRODUCTION/PURPOSE: In vivo detection of cerebral microbleeds (CMBs) from T2* gradient recalled echo (GRE) magnitude image suffers from low specificity, modest inter-rater reproducibility and is biased by its sensitivity to acquisition parameters. New methods were proposed for improving this identification, but they mostly rely on 3D acquisitions, not always feasible in clinical practice. A fast 2D phase processing technique for computing internal field maps (IFM) has been shown to make it possible to characterize CMBs through their magnetic signature in routine clinical setting, based on 2D multi-slice acquisitions. However, its clinical interest for CMBs identification with respect to more common images remained to be assessed. To do so, systematic experiments were undertaken to compare the ratings obtained by trained observers with several image types, T2* magnitude, Susceptibility Weighted Imaging reconstructions (SWI) and IFM built from the same T2*-weighted acquisition. MATERIALS/METHODS: 15 participants from the MEMENTO multi-center cohort were selected: six subjects with numerous CMBs (20 ± 6 CMBs), five subjects with a few CMBs (2 ± 1 CMBs) and four subjects without CMB. 2D multi-slice T2* GRE sequences were acquired on Philips and Siemens 3T systems. After pilot experiments, T2* magnitude, Susceptibility Weighted Imaging (SWI) minimum intensity projection (mIP) on three slices and IFM were considered for the rating experiments. A graphical user interface (GUI) was designed in order to consistently display images in random order. Six raters of various background and expertise independently selected "definite" or "possible" CMBs. Rating results were compared with respect to a specific consensus reference, on both lesion and subject type points of view. RESULTS: IFM yielded increased sensitivity and decreased false positives rate (FPR) for CMBs identification compared to T2* magnitude and SWI-mIP images. Inter-rater variability was decreased with IFM when identifying subjects with numerous lesions, with only a limited increase in rating time. IFM thus appears as an interesting candidate to improve CMBs identification in clinical setting.

Associations between white matter hyperintensities and cognitive decline over three years in non-dementia older adults with memory complaints.

We investigated whether the baseline level and overtime changes of white matter hyperintensities (WMH) would be associated with cognitive decline over three years in non-demented older adults with memory complaints. 109 participants with baseline magnetic resonance imaging (MRI) and follow-up cognitive assessments up to 3-year were included; among them, 82 also had a follow-up MRI assessment over three years. WMH volume was obtained by an automated segmentation algorithm. Baseline WMH volumes and change between baseline and follow-up WMH were related to cognitive scores over time using mixed-effect linear regressions. Secondary stratified analyses according to Clinical Dementia Rating (CDR) status, APOE4 status, and presence of amyloid in the brain were conducted using similar regression models. Change in WMH volume overtime was associated with declines in COWAT (ß=-0.239; 95% CI=-0.381, -0.096, p=0.001). Baseline WMH was not associated to any of the cognitive tests. Secondary analysis found that baseline WMH was associated to declines in TMT-A in APOE4 non-carriers (ß=0.343; 95% CI=0.121, 0.564, p=0.003) and CDR 0 groups (ß=0.307; 95% CI=0.095, 0.519, p=0.005); in CDR 0 group, overtime changes in WMH was associated to declines on both TMT-A (ß=0.698; 95% CI=0.270, 1.126, p=0.002) and TMT-B (ß=2.573; 95% CI=1.200, 3.947, p<0.001). Changes in WMH volume are associated with declines in information processing speed and executive function in non-demented older adults with memory complaints. Overtime changes in WMH volume is probably a better determinant of cognitive function in the elderly than baseline WMH volume.

CATI: A Large Distributed Infrastructure for the Neuroimaging of Cohorts.

This paper provides an overview of CATI, a platform dedicated to multicenter neuroimaging. Initiated by the French Alzheimer's plan (2008-2012), CATI is a research project called on to provide service to other projects like an industrial partner. Its core mission is to support the neuroimaging of large populations, providing concrete solutions to the increasing complexity involved in such projects by bringing together a service infrastructure, the know-how of its expert academic teams and a large-scale, harmonized network of imaging facilities. CATI aims to make data sharing across studies easier and promotes sharing as much as possible. In the last 4 years, CATI has assisted the clinical community by taking charge of 35 projects so far and has emerged as a recognized actor at the national and international levels.