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Acta Neuropathologica Jul 2022Limbic-predominant age-related TDP-43 encephalopathy neuropathological change (LATE-NC) is most often seen in the oldest-old (≥ 90 years of age) but can also be...
Limbic-predominant age-related TDP-43 encephalopathy neuropathological change (LATE-NC) is most often seen in the oldest-old (≥ 90 years of age) but can also be present in the younger-old (< 90 years of age). In this study, we compared the neuropathological associations of LATE-NC and contribution of LATE-NC to cognitive impairment between the oldest-old and younger-old. We observed significant differences in the prevalence of LATE-NC and its association with other co-pathologies in these two age groups. LATE-NC was present in 30.9% (34/110) of the oldest-old but only 9.4% (19/203) of the younger-old. Participants of the oldest-old with LATE-NC were more likely to have hippocampal sclerosis (HS) (55.9% vs. 10.5%, p < 0.001) and moderate to severe arteriolosclerosis (82.4% vs. 50%, p = 0.007), but not intermediate to high Alzheimer's disease neuropathologic change (ADNC) (70.6% vs. 59.2%, p = 0.486) or Lewy body disease (LBD) (20.6% vs. 26.3%, p = 0.793). Participants of the younger-old with LATE-NC were more likely to have intermediate to high ADNC (94.7% vs. 55.4%, p < 0.001) and LBD (63.2% vs. 28.8%, p = 0.013) in addition to hippocampal sclerosis (42.1% vs. 6.5%, p < 0.001), and moderate to severe arteriolosclerosis (42.1% vs. 15.2%, p = 0.020). Of note, participants with LATE-NC and no to low ADNC were very rare in the younger-old (< 1%) but relatively common in the oldest-old (9.1%). Logistic regression modeling showed that in the oldest-old, both intermediate to high ADNC and LATE-NC were independently associated with higher odds of having dementia (OR: 5.09, 95% CI [1.99, 13.06], p < 0.001 for ADNC; OR: 3.28, 95% CI [1.25, 8.57], p = 0.015 for LATE-NC). In the younger-old, by contrast, intermediate to high ADNC and LBD were independently associated with higher odds of having dementia (OR: 4.43, 95% CI [2.27, 8.63], p < 0.001 for ADNC; OR: 2.55, 95% CI [1.21, 5.35], p < 0.014 for LBD), whereas LATE-NC did not show an independent association with dementia. Overall, LATE-NC is strongly associated with arteriolosclerosis and HS in both groups; however, in the younger-old, LATE-NC is associated with other neurodegenerative pathologies, such as ADNC and LBD; whereas in the oldest-old, LATE-NC can exist independent of significant ADNC.
Topics: Aged, 80 and over; Alzheimer Disease; Arteriolosclerosis; DNA-Binding Proteins; Humans; Lewy Body Disease; Sclerosis
PubMed: 35551470
DOI: 10.1007/s00401-022-02432-5 -
Neurology Dec 2020To test the hypothesis that degree of frailty and neuropathologic burden independently contribute to global cognition and odds of dementia.
OBJECTIVE
To test the hypothesis that degree of frailty and neuropathologic burden independently contribute to global cognition and odds of dementia.
METHODS
This was a secondary analysis of a prospective cohort study of older adults living in Illinois. Participants underwent an annual neuropsychological and clinical evaluation. We included 625 participants (mean age 89.7 ± 6.1 years; 67.5% female) who died and underwent autopsy. We quantified neuropathology using an index measure of 10 neuropathologic features: β-amyloid deposition, hippocampal sclerosis, Lewy bodies, tangle density, TDP-43, cerebral amyloid angiopathy, arteriolosclerosis, atherosclerosis, and gross and chronic cerebral infarcts. Clinical consensus determined dementia status, which we coded as no cognitive impairment, mild cognitive impairment, or dementia. A battery of 19 tests spanning multiple domains quantified global cognition. We operationalized frailty using a 41-item frailty index. We employed regression analyses to model relationships between neuropathology, frailty, and dementia.
RESULTS
Both frailty and a neuropathology index were independently associated with global cognition and dementia status. These results held after controlling for traditional pathologic measures in a sample of participants with Alzheimer clinical syndrome. Frailty improved the fit of the model for dementia status (χ[2] 72.64; < 0.0001) and explained an additional 11%-12% of the variance in the outcomes.
CONCLUSION
Dementia is a multiply determined condition, to which both general health, as captured by frailty, and neuropathology significantly contribute. This integrative view of dementia and health has implications for prevention and therapy; specifically, future research should evaluate frailty as a means of dementia risk reduction.
Topics: Aged; Aged, 80 and over; Cognition Disorders; Comorbidity; Dementia; Female; Frailty; Humans; Illinois; Male; Prospective Studies; Regression Analysis
PubMed: 32989103
DOI: 10.1212/WNL.0000000000010944 -
Alzheimer's & Dementia : the Journal of... Sep 2019We classified individuals based on their baseline performance on cognitive measures and investigated the association between cognitive classifications and...
INTRODUCTION
We classified individuals based on their baseline performance on cognitive measures and investigated the association between cognitive classifications and neuropathological findings ∼7 years later, as an external validator.
METHODS
Brain autopsies of 779 decedents were examined. Baseline latent class analysis on 10 neuropsychological measures was previously assigned: mixed-domains impairment (n = 39, 5%), memory-specific impairment (n = 210, 27%), frontal impairment (n = 113, 14.5%), average cognition (n = 360, 46.2%), and superior cognition (n = 57, 7.3%). Linear regressions and risks ratios were used to examine the relation of latent class assignment at enrollment with neuropathological indices.
RESULTS
Amyloid β, tau, and transactive response DNA-binding protein 43 were associated with mixed-domains impairment and memory-specific impairment classes ∼7 years before death. Moderate arteriolosclerosis was associated with membership in the frontal impairment class.
DISCUSSION
Our findings support the use of latent class models that incorporate more comprehensive neuropsychological measures to classify cognitive impairment.
Topics: Aged, 80 and over; Amyloid beta-Peptides; Autopsy; Brain; Cognition; Cognitive Dysfunction; Female; Humans; Male; Memory Disorders; Neuropathology; Neuropsychological Tests; tau Proteins
PubMed: 31420203
DOI: 10.1016/j.jalz.2019.05.012 -
The Lancet. Healthy Longevity Apr 2023VERTIS CV was a randomised, double-blind, placebo-controlled, parallel-group, multicentre cardiovascular outcomes trial that evaluated the cardiovascular efficacy and... (Randomized Controlled Trial)
Randomized Controlled Trial
Cardiorenal outcomes, kidney function, and other safety outcomes with ertugliflozin in older adults with type 2 diabetes (VERTIS CV): secondary analyses from a randomised, double-blind trial.
BACKGROUND
VERTIS CV was a randomised, double-blind, placebo-controlled, parallel-group, multicentre cardiovascular outcomes trial that evaluated the cardiovascular efficacy and safety of ertugliflozin in adults with type 2 diabetes and atherosclerotic cardiovascular disease. The primary objective of VERTIS CV was to show non-inferiority of ertugliflozin to placebo with respect to the primary outcome, major adverse cardiovascular events (a composite of death from cardiovascular causes, non-fatal myocardial infarction, or non-fatal stroke). The analyses reported here aimed to assess cardiorenal outcomes, kidney function, and other safety outcomes with ertugliflozin in older adults with type 2 diabetes and atherosclerotic cardiovascular disease compared with younger participants.
METHODS
VERTIS CV was done at 567 centres in 34 countries. Participants (aged ≥40 years) with type 2 diabetes and atherosclerotic cardiovascular disease were randomly assigned (1:1:1) to once-daily ertugliflozin 5 mg, ertugliflozin 15 mg, or placebo in addition to background standard-of-care treatment. Random assignment was done with the use of an interactive voice-response system. The study outcomes were major adverse cardiovascular events, hospitalisation for heart failure or cardiovascular death, cardiovascular death, hospitalisation for heart failure, prespecified kidney composite outcomes, kidney function, and other assessments of safety. Cardiorenal outcomes, kidney function, and safety outcomes were evaluated by baseline age (≥65 years and <65 years [prespecified] and ≥75 years and <75 years [post hoc]). The study is registered with ClinicalTrials.gov, NCT01986881.
FINDINGS
Between Dec 13, 2013, and July 31, 2015, and between June 1, 2016, and April 14, 2017, 8246 adults with type 2 diabetes and atherosclerotic cardiovascular disease were recruited to the study and randomly assigned. 2752 patients were assigned to ertugliflozin 5 mg, 2747 patients to ertugliflozin 15 mg, and 2747 patients to placebo. 8238 participants received at least one dose of ertugliflozin 5 mg, ertugliflozin 15 mg, or placebo. 4145 (50·3%) of 8238 participants were aged 65 years and older, including 903 (11·0%) participants aged 75 years and older. 5764 (70·0%) of 8238 participants were male and 2474 (30·0%) were female, and 7233 (87·8%) of 8238 participants were White, 497 (6·0%) were Asian, 235 (2·9%) were Black, and 273 (3·3%) were classified as other. The mean estimated glomerular filtration rate (eGFR) was lower and the type 2 diabetes duration longer for those aged 65 years and older versus those younger than 65 years, and for those aged 75 years and older versus those younger than 75 years. Cardiovascular outcomes were more common in the older age subgroups than in the younger age subgroups. Similar to the overall VERTIS CV cohort, ertugliflozin did not increase the risk of major adverse cardiovascular events, cardiovascular death or hospitalisation for heart failure, cardiovascular death alone, or the kidney composite outcome (using doubling of serum creatinine, dialysis or transplantation, or kidney death), and reduced the risk of hospitalisation for heart failure and the exploratory kidney composite outcome (using a 40% sustained eGFR decrease, dialysis or transplantation, or kidney death) in the older age subgroups (p>0·05 for outcomes assessed). A slower decline in eGFR and a smaller increase in the urine albumin-to-creatinine ratio were observed over time in all age subgroups taking ertugliflozin compared with placebo. Across age subgroups, safety outcomes were consistent with the known profile of ertugliflozin.
INTERPRETATION
The effects of ertugliflozin on cardiorenal outcomes, kidney function, and safety outcomes were generally similar across age subgroups. These results have the potential to help clinical decision making by providing a longer-term evaluation of the cardiorenal safety and overall tolerability of ertugliflozin in a large population of older adults.
FUNDING
Merck Sharp & Dohme LLC, a subsidiary of Merck & Co, Inc, Rahway, NJ, USA in collaboration with Pfizer Inc, New York, NY, USA.
Topics: Humans; Female; Aged; Aged, 80 and over; Arteriolosclerosis; Diabetes Mellitus, Type 2; Double-Blind Method; Myocardial Infarction; Renal Dialysis; Sodium-Glucose Transporter 2; Standard of Care; Kidney; Treatment Outcome
PubMed: 37003273
DOI: 10.1016/S2666-7568(23)00032-6 -
Journal of Alzheimer's Disease : JAD 2021Blood pressure variability is linked to Alzheimer's disease (AD) risk and MRI-based markers of cerebrovascular disease. Less is known about the role of blood pressure...
BACKGROUND
Blood pressure variability is linked to Alzheimer's disease (AD) risk and MRI-based markers of cerebrovascular disease. Less is known about the role of blood pressure variability in postmortem evaluation of cerebrovascular disease and AD.
OBJECTIVE
To determine whether antemortem blood pressure variability predicts cerebrovascular and AD pathology and follow-up cognitive change in autopsy-confirmed AD.
METHODS
National Alzheimer's Coordinating Center participants (n = 513) underwent 3-4 approximately annual blood pressure measurements and were confirmed to have AD at postmortem evaluation. A subset (n = 493) underwent neuropsychological evaluation at follow-up. Regression models examined relationships between blood pressure variability and cerebrovascular and AD pathological features and follow-up cognitive change.
RESULTS
Elevated blood pressure variability predicted increased postmortem cerebrovascular lesion burden (ß = 0.26 [0.10, 0.42]; p = 0.001; R2 = 0.12). Increased blood pressure variability predicted specific cerebrovascular lesion severity, including atherosclerosis in the Circle of Willis (OR = 1.22 [1.03, 1.44]; p = 0.02) and cerebral arteriolosclerosis (OR = 1.32 [1.04, 1.69]; p = 0.03). No significant relationships were observed between blood pressure variability and AD pathological findings, including Braak & Braak stage, neuritic plaques or diffuse plaques, or cerebral amyloid angiopathy, or follow-up cognitive decline.
CONCLUSION
Findings suggest that elevated blood pressure variability is related to postmortem cerebrovascular lesion burden in autopsy-confirmed AD, independent of average blood pressure and AD neuropathology. Blood pressure fluctuation may selectively promote atherosclerotic and arteriolosclerotic brain lesions with potential implications for cognitive impairment and dementia.
Topics: Aged; Alzheimer Disease; Autopsy; Blood Pressure; Cerebrovascular Disorders; Female; Humans; Magnetic Resonance Imaging; Male; Neuropathology; Neuropsychological Tests
PubMed: 34250941
DOI: 10.3233/JAD-210435 -
Neurology Apr 2022Limbic-predominant age-related Tar DNA binding protein 43 (TDP-43) encephalopathy neuropathologic change (LATE-NC) is present in ≈25% of older persons' brains and is...
BACKGROUND AND OBJECTIVES
Limbic-predominant age-related Tar DNA binding protein 43 (TDP-43) encephalopathy neuropathologic change (LATE-NC) is present in ≈25% of older persons' brains and is strongly associated with cognitive impairment. Hippocampal sclerosis (HS) pathology is often comorbid with LATE-NC, but the clinical and pathologic correlates of HS in LATE-NC are not well understood.
METHODS
This retrospective autopsy cohort study used data derived from the National Alzheimer's Coordinating Center Neuropathology Data Set, which included neurologic status, medical histories, and neuropathologic results. All autopsies were performed in 2014 or later. Among participants with LATE-NC, those who also had HS pathology were compared with those without HS with regard to candidate risk factors or common underlying diseases. Statistical significance was set at nominal < 0.05 in this exploratory study.
RESULTS
A total of 408 participants were included (n = 221 were LATE-NC+/HS-, n = 145 were LATE-NC+/HS+, and n = 42 were LATE-NC-/HS+). Most of the included LATE-NC+ participants were severely impaired cognitively (83.3% with dementia). Compared to HS- participants, LATE-NC+ participants with HS trended toward having worse cognitive status and scored lower on the Personal Care and Orientation domains (both = 0.03). Among LATE-NC+ participants with Braak neurofibrillary tangle (NFT) stages 0 to IV (n = 88), HS+ participants were more impaired in the Memory and Orientation domains (both = 0.02). There were no differences (HS+ compared with HS-) in the proportion with clinical histories of seizures, stroke, cardiac bypass procedures, diabetes, or hypertension. The HS+ group lacking TDP-43 proteinopathy (n = 42) was relatively likely to have had strokes ( = 0.03). When LATE-NC+ participants with or without HS were compared, there were no differences in Alzheimer disease neuropathologies (Thal β-amyloid phases or Braak NFT stages) or Lewy body pathologies. However, the HS+ group was less likely to have amygdala-restricted TDP-43 proteinopathy (LATE-NC stage 1) and more likely to have neocortical TDP-43 proteinopathy (LATE-NC stage 3) ( < 0.001). LATE-NC+ brains with HS also tended to have more severe circle of Willis atherosclerosis and arteriolosclerosis pathologies.
DISCUSSION
In this cohort skewed toward participants with severe dementia, LATE-NC+ HS pathology was not associated with seizures or with Alzheimer-type pathologies. Rather, the presence of comorbid HS pathology was associated with more widespread TDP-43 proteinopathy and with more severe non-β-amyloid vessel wall pathologies.
Topics: Aged; Aged, 80 and over; Alzheimer Disease; Cohort Studies; DNA-Binding Proteins; Hippocampus; Humans; Retrospective Studies; Sclerosis; TDP-43 Proteinopathies
PubMed: 35121671
DOI: 10.1212/WNL.0000000000200001 -
Stroke Jan 2022Cerebrovascular disease (CVD) pathologies including vessel disease (atherosclerosis, arteriolosclerosis, and cerebral amyloid angiopathy) and tissue injury...
BACKGROUND AND PURPOSE
Cerebrovascular disease (CVD) pathologies including vessel disease (atherosclerosis, arteriolosclerosis, and cerebral amyloid angiopathy) and tissue injury (macroinfarcts and microinfarcts) each contribute to Alzheimer and other forms of dementia. CVD is often a complex mix of neuropathologies, with little known about the frequencies of differing combinations or their associations with cognition.
METHODS
We investigated 32 possible CVD combinations (3 types of vessel disease and 2 types of tissue injury) using autopsy data from 1474 decedents (≈88 years at death; 65% female) of Rush Alzheimer's Disease Center studies. We determined frequencies of all 32 CVD combinations and their relationships with global and domain-specific cognitive decline using mixed-effect models adjusted for demographics, neuropathologies, time before death, and interactions of these variables with time.
RESULTS
Of the 1184 decedents with CVD neuropathology (80% of the total sample), 37% had a single CVD (67-148 decedents/group) while 63% had mixed CVD profiles (11-54 decedents/group). When considered as 2 distinct groups, the mixed CVD profile group (but not the single CVD profile group) showed a faster cognitive decline across all domains assessed compared with decedents without CVD neuropathology. Most mixed CVD profiles, especially those involving both atherosclerosis and arteriolosclerosis, showed faster cognitive decline than any single CVD profile considered alone; specific mixed CVD profiles differentially associated with individual cognitive domains.
CONCLUSIONS
Mixed CVD, more common than single CVD, is associated with cognitive decline, and distinct mixed CVD profiles show domain-specific associations with cognitive decline. CVD is not monolithic but consists of heterogenous person-specific combinations with distinct contributions to cognitive decline.
Topics: Aged, 80 and over; Aging; Brain; Cerebrovascular Disorders; Cognitive Dysfunction; Cohort Studies; Female; Humans; Male; Prospective Studies
PubMed: 34601898
DOI: 10.1161/STROKEAHA.121.034814 -
Acta Neuropathologica Dec 2021Cerebral white matter lesions (WML) encompass axonal loss and demyelination and are assumed to be associated with small vessel disease (SVD)-related ischaemia. However,...
Cerebral white matter lesions (WML) encompass axonal loss and demyelination and are assumed to be associated with small vessel disease (SVD)-related ischaemia. However, our previous study in the parietal lobe white matter revealed that WML in Alzheimer's disease (AD) are linked with degenerative axonal loss secondary to the deposition of cortical AD pathology. Furthermore, neuroimaging data suggest that pathomechanisms for the development of WML differ between anterior and posterior lobes with AD-associated degenerative mechanism driving posterior white matter disruption, and both AD-associated degenerative and vascular mechanisms contributed to anterior matter disruption. In this pilot study, we used human post-mortem brain tissue to investigate the composition and aetiology of frontal WML from AD and non-demented controls to determine if frontal WML are SVD-associated and to reveal any regional differences in the pathogenesis of WML. Frontal WML tissue sections from 40 human post-mortem brains (AD, n = 19; controls, n = 21) were quantitatively assessed for demyelination, axonal loss, cortical hyperphosphorylated tau (HPτ) and amyloid-beta (Aβ) burden, and arteriolosclerosis as a measure of SVD. Biochemical assessment included Wallerian degeneration-associated protease calpain and the myelin-associated glycoprotein to proteolipid protein ratio as a measure of ante-mortem ischaemia. Arteriolosclerosis severity was found to be associated with and a significant predictor of frontal WML severity in both AD and non-demented controls. Interesting, frontal axonal loss was also associated with HPτ and calpain levels were associated with increasing Aβ burden in the AD group, suggestive of an additional degenerative influence. To conclude, this pilot data suggest that frontal WML in AD may result from both increased arteriolosclerosis and AD-associated degenerative changes. These preliminary findings in combination with previously published data tentatively indicate regional differences in the aetiology of WML in AD, which should be considered in the clinical diagnosis of dementia subtypes: posterior WML maybe associated with degenerative mechanisms secondary to AD pathology, while anterior WML could be associated with both SVD-associated and degenerative mechanisms.
Topics: Aged; Aged, 80 and over; Alzheimer Disease; Cerebral Small Vessel Diseases; Female; Frontal Lobe; Humans; Intracranial Arteriosclerosis; Male; Pilot Projects; White Matter
PubMed: 34608542
DOI: 10.1007/s00401-021-02376-2 -
Frontiers in Neurology 2022Twenty-four-hour and nighttime blood pressure (BP) levels are more strongly associated with cardiovascular risk than office or daytime BP measurements. However, it...
BACKGROUND
Twenty-four-hour and nighttime blood pressure (BP) levels are more strongly associated with cardiovascular risk than office or daytime BP measurements. However, it remains undocumented which of the office and ambulatory BP measurements have the strongest association and predictive information in relation to the presence of type I, or arteriolosclerosis type, cerebral small vessel diseases (CSVD).
METHODS
A subset of 429 participants from the Maracaibo Aging Study [aged ≥40 years (women, 73.7%; mean age, 59.3 years)] underwent baseline brain magnetic resonance imaging (MRI) to visualize CSVD, which included log-transformed white matter hyperintensities (log-WMH) volume and the presence (yes/no) of lacunes, cerebral microbleeds (CMB), or enlarged perivascular spaces (EPVS). Linear and logistic regression models were applied to examine the association between CSVD and each +10-mmHg increment in the office and ambulatory systolic BP measurements. Improvement in the fit of nested logistic models was assessed by the log-likelihood ratio and the generalized statistic.
RESULTS
Office and ambulatory systolic BP measurements were related to log-WMH (βcorrelation coefficients ≥0.08; < 0.001). Lacunes and CMB were only associated with ambulatory systolic BP measurements (odds ratios [OR] ranged from 1.31 [95% confidence interval, 1.10-1.55] to 1.46 [1.17-1.84], ≤ 0.003). Accounted for daytime systolic BP, both the 24-h (β-correlation, 0.170) and nighttime (βcorrelation, 0.038) systolic BP measurements remained related to log-WMH. When accounted for 24-h or daytime systolic BP levels, the nighttime systolic BP retained the significant association with lacunes (ORs, 1.05-1.06; 95% CIs, ≥1.01 to ≤ 1.13), whereas the 24-h and daytime systolic BP levels were not associated with lacunes after adjustments for nighttime systolic BP (ORs, ≤ 0.88; 95% CI, ≥0.77 to ≤ 1.14). On top of covariables and office systolic BP, ambulatory systolic BP measurements significantly improved model performance (1.05% ≥ ≤ 3.82%). Compared to 24-h and daytime systolic BP, nighttime systolic BP had the strongest improvement in the model performance; for WMH (1.46 vs. 1.05%) and lacunes (3.06 vs. ≤ 2.05%).
CONCLUSIONS
Twenty-four-hour and nighttime systolic BP were the more robust BP measurements associated with CSVD, but the nighttime systolic BP level had the strongest association. Controlling ambulatory BP levels might provide additional improvement in the prevention of CSVD.
PubMed: 35911921
DOI: 10.3389/fneur.2022.908260 -
Alzheimer's & Dementia : the Journal of... Apr 2021The concept of vascular contributions to cognitive impairment and dementia (VCID) derives from more than two decades of research indicating that (1) most older...
The concept of vascular contributions to cognitive impairment and dementia (VCID) derives from more than two decades of research indicating that (1) most older individuals with cognitive impairment have post mortem evidence of multiple contributing pathologies and (2) along with the preeminent role of Alzheimer's disease (AD) pathology, cerebrovascular disease accounts for a substantial proportion of this contribution. Contributing cerebrovascular processes include both overt strokes caused by etiologies such as large vessel occlusion, cardioembolism, and embolic infarcts of unknown source, and frequently asymptomatic brain injuries caused by diseases of the small cerebral vessels. Cerebral small vessel diseases such as arteriolosclerosis and cerebral amyloid angiopathy, when present at moderate or greater pathologic severity, are independently associated with worse cognitive performance and greater likelihood of dementia, particularly in combination with AD and other neurodegenerative pathologies. Based on this evidence, the US National Alzheimer's Project Act explicitly authorized accelerated research in vascular and mixed dementia along with frontotemporal and Lewy body dementia and AD itself. Biomarker development has been consistently identified as a key step toward translating scientific advances in VCID into effective prevention and treatment strategies. Validated biomarkers can serve a range of purposes in trials of candidate interventions, including (1) identifying individuals at increased VCID risk, (2) diagnosing the presence of cerebral small vessel disease or specific small vessel pathologies, (3) stratifying study participants according to their prognosis for VCID progression or treatment response, (4) demonstrating an intervention's target engagement or pharmacodynamic mechanism of action, and (5) monitoring disease progression during treatment. Effective biomarkers allow academic and industry investigators to advance promising interventions at early stages of development and discard interventions with low success likelihood. The MarkVCID consortium was formed in 2016 with the goal of developing and validating fluid- and imaging-based biomarkers for the cerebral small vessel diseases associated with VCID. MarkVCID consists of seven project sites and a central coordinating center, working with the National Institute of Neurologic Diseases and Stroke and National Institute on Aging under cooperative agreements. Through an internal selection process, MarkVCID has identified a panel of 11 candidate biomarker "kits" (consisting of the biomarker measure and the clinical and cognitive data used to validate it) and established a range of harmonized procedures and protocols for participant enrollment, clinical and cognitive evaluation, collection and handling of fluid samples, acquisition of neuroimaging studies, and biomarker validation. The overarching goal of these protocols is to generate rigorous validating data that could be used by investigators throughout the research community in selecting and applying biomarkers to multi-site VCID trials. Key features of MarkVCID participant enrollment, clinical/cognitive testing, and fluid biomarker procedures are summarized here, with full details in the following text, tables, and supplemental material, and a description of the MarkVCID imaging biomarker procedures in a companion paper, "MarkVCID Cerebral small vessel consortium: II. Neuroimaging protocols." The procedures described here address a range of challenges in MarkVCID's design, notably: (1) acquiring all data under informed consent and enrollment procedures that allow unlimited sharing and open-ended analyses without compromising participant privacy rights; (2) acquiring the data in a sufficiently wide range of study participants to allow assessment of candidate biomarkers across the various patient groups who might ultimately be targeted in VCID clinical trials; (3) defining a common dataset of clinical and cognitive elements that contains all the key outcome markers and covariates for VCID studies and is realistically obtainable during a practical study visit; (4) instituting best fluid-handling practices for minimizing avoidable sources of variability; and (5) establishing rigorous procedures for testing the reliability of candidate fluid-based biomarkers across replicates, assay runs, sites, and time intervals (collectively defined as the biomarker's instrumental validity). Participant Enrollment Project sites enroll diverse study cohorts using site-specific inclusion and exclusion criteria so as to provide generalizable validation data across a range of cognitive statuses, risk factor profiles, small vessel disease severities, and racial/ethnic characteristics representative of the diverse patient groups that might be enrolled in a future VCID trial. MarkVCID project sites include both prospectively enrolling centers and centers providing extant data and samples from preexisting community- and population-based studies. With approval of local institutional review boards, all sites incorporate MarkVCID consensus language into their study documents and informed consent agreements. The consensus language asks prospectively enrolled participants to consent to unrestricted access to their data and samples for research analysis within and outside MarkVCID. The data are transferred and stored as a de-identified dataset as defined by the Health Insurance Portability and Accountability Act Privacy Rule. Similar human subject protection and informed consent language serve as the basis for MarkVCID Research Agreements that act as contracts and data/biospecimen sharing agreements across the consortium. Clinical and Cognitive Data Clinical and cognitive data are collected across prospectively enrolling project sites using common MarkVCID instruments. The clinical data elements are modified from study protocols already in use such as the Alzheimer's Disease Center program Uniform Data Set Version 3 (UDS3), with additional focus on VCID-related items such as prior stroke and cardiovascular disease, vascular risk factors, focal neurologic findings, and blood testing for vascular risk markers and kidney function including hemoglobin A1c, cholesterol subtypes, triglycerides, and creatinine. Cognitive assessments and rating instruments include the Clinical Dementia Rating Scale, Geriatric Depression Scale, and most of the UDS3 neuropsychological battery. The cognitive testing requires ≈60 to 90 minutes. Study staff at the prospectively recruiting sites undergo formalized training in all measures and review of their first three UDS3 administrations by the coordinating center. Collection and Handling of Fluid Samples Fluid sample types collected for MarkVCID biomarker kits are serum, ethylenediaminetetraacetic acid-plasma, platelet-poor plasma, and cerebrospinal fluid (CSF) with additional collection of packed cells to allow future DNA extraction and analyses. MarkVCID fluid guidelines to minimize variability include fasting morning fluid collections, rapid processing, standardized handling and storage, and avoidance of CSF contact with polystyrene. Instrumental Validation for Fluid-Based Biomarkers Instrumental validation of MarkVCID fluid-based biomarkers is operationally defined as determination of intra-plate and inter-plate repeatability, inter-site reproducibility, and test-retest repeatability. MarkVCID study participants both with and without advanced small vessel disease are selected for these determinations to assess instrumental validity across the full biomarker assay range. Intra- and inter-plate repeatability is determined by repeat assays of single split fluid samples performed at individual sites. Inter-site reproducibility is determined by assays of split samples distributed to multiple sites. Test-retest repeatability is determined by assay of three samples acquired from the same individual, collected at least 5 days apart over a 30-day period and assayed on a single plate. The MarkVCID protocols are designed to allow direct translation of the biomarker validation results to multicenter trials. They also provide a template for outside groups to perform analyses using identical methods and therefore allow direct comparison of results across studies and centers. All MarkVCID protocols are available to the biomedical community and intended to be shared. In addition to the instrumental validation procedures described here, each of the MarkVCID kits will undergo biological validation to determine whether the candidate biomarker measures important aspects of VCID such as cognitive function. Analytic methods and results of these validation studies for the 11 MarkVCID biomarker kits will be published separately. The results of this rigorous validation process will ultimately determine each kit's potential usefulness for multicenter interventional trials aimed at preventing or treating small vessel disease related VCID.
Topics: Aged; Biomarkers; Cerebral Small Vessel Diseases; Cognitive Dysfunction; Dementia; Disease Progression; Female; Humans; Information Dissemination; Male; Neuropsychological Tests; Patient Selection; Research Design; Stroke
PubMed: 33480172
DOI: 10.1002/alz.12215