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1.
PLoS Genet ; 17(4): e1009482, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33798195

RESUMO

Transcriptome-wide association studies (TWAS) have been widely used to integrate transcriptomic and genetic data to study complex human diseases. Within a test dataset lacking transcriptomic data, traditional two-stage TWAS methods first impute gene expression by creating a weighted sum that aggregates SNPs with their corresponding cis-eQTL effects on reference transcriptome. Traditional TWAS methods then employ a linear regression model to assess the association between imputed gene expression and test phenotype, thereby assuming the effect of a cis-eQTL SNP on test phenotype is a linear function of the eQTL's estimated effect on reference transcriptome. To increase TWAS robustness to this assumption, we propose a novel Variance-Component TWAS procedure (VC-TWAS) that assumes the effects of cis-eQTL SNPs on phenotype are random (with variance proportional to corresponding reference cis-eQTL effects) rather than fixed. VC-TWAS is applicable to both continuous and dichotomous phenotypes, as well as individual-level and summary-level GWAS data. Using simulated data, we show VC-TWAS is more powerful than traditional TWAS methods based on a two-stage Burden test, especially when eQTL genetic effects on test phenotype are no longer a linear function of their eQTL genetic effects on reference transcriptome. We further applied VC-TWAS to both individual-level (N = ~3.4K) and summary-level (N = ~54K) GWAS data to study Alzheimer's dementia (AD). With the individual-level data, we detected 13 significant risk genes including 6 known GWAS risk genes such as TOMM40 that were missed by traditional TWAS methods. With the summary-level data, we detected 57 significant risk genes considering only cis-SNPs and 71 significant genes considering both cis- and trans- SNPs, which also validated our findings with the individual-level GWAS data. Our VC-TWAS method is implemented in the TIGAR tool for public use.

2.
Stroke ; : STROKEAHA120030226, 2021 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-33840227

RESUMO

BACKGROUND AND PURPOSE: The general cardiovascular Framingham risk score (FRS) identifies adults at increased risk for stroke. We tested the hypothesis that baseline FRS is associated with the presence of postmortem cerebrovascular disease (CVD) pathologies. METHODS: We studied the brains of 1672 older decedents with baseline FRS and measured CVD pathologies including macroinfarcts, microinfarcts, atherosclerosis, arteriolosclerosis, and cerebral amyloid angiopathy. We employed a series of logistic regressions to examine the association of baseline FRS with each of the 5 CVD pathologies. RESULTS: Average age at baseline was 80.5±7.0 years and average age at death was 89.2±6.7 years. A higher baseline FRS was associated with higher odds of macroinfarcts (odds ratio, 1.10 [95% CI, 1.07-1.13], P<0.001), microinfarcts (odds ratio, 1.04 [95% CI, 1.01-1.07], P=0.009), atherosclerosis (odds ratio, 1.07 [95% CI, 1.04-1.11], P<0.001), and arteriolosclerosis (odds ratio, 1.04 [95% CI, 1.01-1.07], P=0.005). C statistics for these models ranged from 0.537 to 0.595 indicating low accuracy for predicting CVD pathologies. FRS was not associated with the presence of cerebral amyloid angiopathy. CONCLUSIONS: A higher FRS score in older adults is associated with higher odds of some, but not all, CVD pathologies, with low discrimination at the individual level. Further work is needed to develop a more robust risk score to identify adults at risk for accumulating CVD pathologies.

3.
Stroke ; : STROKEAHA120030870, 2021 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-33902300

RESUMO

BACKGROUND AND PURPOSE: The pathogenesis of cerebral small vessel disease remains incompletely understood. The relationship between circadian rhythm disturbances and histopathologic measures of cerebral small vessel disease has not been studied. We hypothesized that disrupted circadian rest-activity rhythms would be associated with a higher burden of cerebral small vessel disease pathology. METHODS: We studied 561 community-dwelling older adults (mean age at death, 91.2, 27.4% male) from the Rush Memory and Aging Project. We used actigraphy to quantify several measures of 24-hour rest-activity rhythmicity, including interdaily stability, intradaily variability, and amplitude, and used ordinal logistic regression models to relate these measures to the severity of cerebral arteriolosclerosis, atherosclerosis, macroinfarcts, and microinfarcts, assessed at autopsy. RESULTS: Lower interdaily stability was associated with a higher burden of arteriolosclerosis, higher intradaily variability was associated with a higher burden of atherosclerosis and subcortical infarcts, and lower amplitude was associated with a higher burden of arteriosclerosis, atherosclerosis and subcortical macroinfarcts. Moreover, the associations between interdaily stability and arteriolosclerosis and intradaily variability and subcortical infarcts were independent of cardiovascular risk factors, sleep fragmentation, and medical comorbidities. CONCLUSIONS: Disrupted rest-activity rhythms are associated with a greater burden of cerebral small vessel disease in older adults.

4.
PLoS One ; 16(3): e0240342, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33661922

RESUMO

The inflammatory hypothesis posits that sustained neuroinflammation is sufficient to induce neurodegeneration and the development of Alzheimer's disease (AD) and Alzheimer's dementia. One potential source of inflammation is the intestine which harbors pro-inflammatory microorganisms capable of promoting neuroinflammation. Systemic inflammation is robustly associated with neuroinflammation as well as low levels of brain derived neurotrophic factor (BDNF) in the systemic circulation and brain. Thus, in this pilot study, we tested the hypothesis that intestinal barrier dysfunction precedes risk of death, incident AD dementia and MCI, cognitive impairment and neuropathology. Serum BDNF was associated with changes in global cognition, working memory, and perceptual speed but not risk of death, incident AD dementia, incident MCI, or neuropathology. Neither of the markers of intestinal barrier integrity examined, including lipopolysaccharide binding protein (LBP) nor intestinal fatty acid binding protein (IFABP), were associated with risk of death, incident AD dementia, incident mild cognitive impairment (MCI), change in cognition (global or domains), or neuropathology. Taken together, the data in this pilot study suggest that intestinal barrier dysfunction does not precede diagnosis of AD or MCI, changes in cognition, or brain pathology. However, since MCI and AD are related to global cognition, the findings with BDNF and the contiguous cognitive measures suggest low power with the trichotomous cognitive status measures. Future studies with larger sample sizes are necessary to further investigate the results from this pilot study.

5.
Parkinsonism Relat Disord ; 84: 105-111, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33607526

RESUMO

INTRODUCTION: Emerging technologies show promise for enhanced characterization of Parkinson's Disease (PD) motor manifestations. We evaluated quantitative mobility measures from a wearable device compared to the conventional motor assessment, the Movement Disorders Society-Unified PD Rating Scale part III (motor MDS-UPDRS). METHODS: We evaluated 176 PD subjects (mean age 65, 65% male, 66% H&Y stage 2) during routine clinic visits using the motor MDS-UPDRS and a 10-min motor protocol with a body-fixed sensor (DynaPort MT, McRoberts BV), including the 32-ft walk, Timed Up and Go (TUG), and standing posture with eyes closed. Regression models examined 12 quantitative mobility measures for associations with (i) motor MDS-UPDRS, (ii) motor subtype (tremor dominant vs. postural instability/gait difficulty), (iii) Montreal Cognitive Assessment (MoCA), and (iv) physical functioning disability (PROMIS-29). All analyses included age, gender, and disease duration as covariates. Models iii-iv were secondarily adjusted for motor MDS-UPDRS. RESULTS: Quantitative mobility measures from gait, TUG transitions, turning, and posture were significantly associated with motor MDS-UPDRS (7 of 12 measures, p < 0.05) and motor subtype (6 of 12 measures, p < 0.05). Compared with motor MDS-UPDRS, several quantitative mobility measures accounted for a 1.5- or 1.9-fold increased variance in either cognition or physical functioning disability, respectively. Among minimally-impaired subjects in the bottom quartile of motor MDS-UPDRS, including subjects with normal gait exam, the measures captured substantial residual motor heterogeneity. CONCLUSION: Clinic-based quantitative mobility assessments using a wearable sensor captured features of motor performance beyond those obtained with the motor MDS-UPDRS and may offer enhanced characterization of disease heterogeneity.

6.
Artigo em Inglês | MEDLINE | ID: mdl-33631006

RESUMO

BACKGROUND: There is paucity of data about African American (AA) patients with Parkinson's disease (PD) and parkinsonism which may precede PD in older adults. Prior studies suggest that there are lower rates of PD in the AA population, with more cognitive impairment in AA with PD. This study aimed to investigate differences in PD, parkinsonism, and cognition between white and AA populations in three longitudinal epidemiologic cohort studies of aging. METHODS: This study examined parkinsonism, PD frequency, and cognition of community dwelling older individuals in three longitudinal epidemiologic cohort studies. Parkinsonism was based on an exam utilizing the modified Unified Parkinson's Disease Rating Scale (UPDRS) performed by a nurse. PD was based on self-report, medications used for treatment of PD, and examination findings. Cognition was assessed using 19 performance-based tests that assess five cognitive domains. RESULTS: AA subjects were less likely to have parkinsonism compared to whites, even with age and gender differences. Frequency of PD was not significant between groups. AA were more likely to have lower cognitive scores as compared to whites. AA were less likely to have parkinsonism even with controlling for cognitive differences between groups. CONCLUSIONS: Parkinsonian signs are present among AAs in the community at lower rates than in white individuals. Cognitive profiles of AA and whites with parkinsonism may be different, suggesting differing contributions of pathology to cognitive decline and parkinsonism between groups. Additional research is needed to understand the progression of parkinsonism to PD, as well as to understanding the cognitive differences in AA with parkinsonism.

7.
PLoS One ; 16(2): e0245680, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33529220

RESUMO

BACKGROUND: This study tested the hypothesis that sarcopenia and its constituent components, reduced lean muscle mass and impaired motor function, are associated with reduced survival and increased risk of incident disabilities. METHODS: 1466 community-dwelling older adults underwent assessment of muscle mass with bioelectrical impedance analysis (BIA), grip strength, gait speed and other components of physical frailty and annual self-report assessments of disability. We used Cox proportional hazards models that controlled for age, sex, race, education and height to examine the associations of a continuous sarcopenia metric with the hazard of death and incident disabilities. RESULTS: Mean baseline age was about 80 years old and follow-up was 5.5 years. In a proportional hazards model controlling for age, sex, race, education and baseline sarcopenia, each 1-SD higher score on a continuous sarcopenia scale was associated with lower hazards of death (HR 0.70, 95%CI [0.62, 0.78]), incident IADL (HR 0.80,95%CI [0.70, 0.93]), incident ADL disability (HR 0.80 95%CI [71, 91]) and incident mobility disability (HR 0.81, 95%CI [0.70, 0.93]). Further analyses suggest that grip strength and gait speed rather than muscle mass drive the associations with all four adverse health outcomes. Similar findings were observed when controlling for additional measures used to assess physical frailty including BMI, fatigue and physical activity. CONCLUSIONS: Motor function is the primary driver of the associations of sarcopenia and physical frailty with diverse adverse health outcomes. Further work is needed to identify other facets of muscle structure and motor function which together can identify adults at risk for specific adverse health outcomes.

8.
PLoS One ; 16(2): e0246206, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33534811

RESUMO

BACKGROUND: Mobility disability and parkinsonism are associated with decreased survival in older adults. This study examined the transition from no motor impairment to mobility disability and parkinsonism and their associations with death. METHODS: 867 community-dwelling older adults without mobility disability or parkinsonism at baseline were examined annually. Mobility disability was based on annual measured gait speed. Parkinsonism was based on the annual assessment of 26 items from the motor portion of the Unified Parkinson's Disease Rating Scale. A multistate Cox model simultaneously examined the incidences of mobility disability and parkinsonism and their associations with death. RESULTS: Average age at baseline was 75 years old and 318 (37%) died during 10 years of follow-up. Mobility disability was almost 2-fold more common than parkinsonism. Some participants developed mobility disability alone (42%), or parkinsonism alone (5%), while many developed both (41%). Individuals with mobility disability or parkinsonism alone had an increased risk of death, but their risk was less than the risk in individuals with both impairments. The risk of death did not depend on the order in which impairments occurred. CONCLUSION: The varied patterns of transitions from no motor impairment to motor impairment highlights the heterogeneity of late-life motor impairment and its contribution to survival. Further studies are needed to elucidate the underlying biology of these different transitions and how they might impact survival.

9.
Nat Commun ; 12(1): 654, 2021 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-33510174

RESUMO

Low muscle strength is an important heritable indicator of poor health linked to morbidity and mortality in older people. In a genome-wide association study meta-analysis of 256,523 Europeans aged 60 years and over from 22 cohorts we identify 15 loci associated with muscle weakness (European Working Group on Sarcopenia in Older People definition: n = 48,596 cases, 18.9% of total), including 12 loci not implicated in previous analyses of continuous measures of grip strength. Loci include genes reportedly involved in autoimmune disease (HLA-DQA1 p = 4 × 10-17), arthritis (GDF5 p = 4 × 10-13), cell cycle control and cancer protection, regulation of transcription, and others involved in the development and maintenance of the musculoskeletal system. Using Mendelian randomization we report possible overlapping causal pathways, including diabetes susceptibility, haematological parameters, and the immune system. We conclude that muscle weakness in older adults has distinct mechanisms from continuous strength, including several pathways considered to be hallmarks of ageing.


Assuntos
Predisposição Genética para Doença/genética , Estudo de Associação Genômica Ampla/métodos , Debilidade Muscular/genética , Sarcopenia/genética , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/genética , Estudos de Coortes , Europa (Continente) , Feminino , Fator 5 de Diferenciação de Crescimento/genética , Cadeias alfa de HLA-DQ/genética , Humanos , Masculino , Pessoa de Meia-Idade , Força Muscular/genética , Força Muscular/fisiologia , Debilidade Muscular/fisiopatologia , Polimorfismo de Nucleotídeo Único , Sarcopenia/fisiopatologia
10.
J Alzheimers Dis ; 2020 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-33185594

RESUMO

BACKGROUND: Vascular mechanisms may contribute to the accumulation of AD pathology. OBJECTIVE: We examined whether the burden of vascular risk factors proximate to death is associated with amyloid-ß and tau levels or modified their known association. METHODS: We examined the brains of 1, 585 participants from two longitudinal community-based studies of older adults. Amyloid-ß and tau were quantified by postmortem examination. The burden of vascular risk factors was summarized by calculating the Framingham general cardiovascular risk score (FRS) proximate to death. Using linear regressions, we examined the association of the FRS with the amyloid-ß and tau levels and examined if the FRS modified the association of the amyloid-ß with tau. RESULTS: On average, participants were nearly 90 years old and two-thirds were women. The FRS was not associated with amyloid-ß (Spearman r  = -0.00, p  = 0.918) or tau (r = 0.01, p = 0.701). However, the FRS as a whole (estimate = -0.022, SE = 0.008, p = 0.009), and specifically the systolic blood pressure (SBP) component (estimate = -0.033, SE = 0.012, p = 0.009), modified the association of the amyloid-ß with tau. Further analysis showed that the association between amyloid-ß and tau was stronger at lower levels of SBP. CONCLUSION: Late-life vascular risk scores were not related to postmortem levels of amyloid-ß or tau. However, lower levels of vascular risk scores and SBP were associated with a stronger association between amyloid-ß and tau. These data suggest that vascular risk factors may modify the relation of AD pathology markers to one another.

11.
Am J Hum Genet ; 107(4): 714-726, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32961112

RESUMO

Transcriptome-wide association studies (TWASs) have been widely used to integrate gene expression and genetic data for studying complex traits. Due to the computational burden, existing TWAS methods do not assess distant trans-expression quantitative trait loci (eQTL) that are known to explain important expression variation for most genes. We propose a Bayesian genome-wide TWAS (BGW-TWAS) method that leverages both cis- and trans-eQTL information for a TWAS. Our BGW-TWAS method is based on Bayesian variable selection regression, which not only accounts for cis- and trans-eQTL of the target gene but also enables efficient computation by using summary statistics from standard eQTL analyses. Our simulation studies illustrated that BGW-TWASs achieved higher power compared to existing TWAS methods that do not assess trans-eQTL information. We further applied BWG-TWAS to individual-level GWAS data (N = ∼3.3K), which identified significant associations between the genetically regulated gene expression (GReX) of ZC3H12B and Alzheimer dementia (AD) (p value = 5.42 × 10-13), neurofibrillary tangle density (p value = 1.89 × 10-6), and global measure of AD pathology (p value = 9.59 × 10-7). These associations for ZC3H12B were completely driven by trans-eQTL. Additionally, the GReX of KCTD12 was found to be significantly associated with ß-amyloid (p value = 3.44 × 10-8) which was driven by both cis- and trans-eQTL. Four of the top driven trans-eQTL of ZC3H12B are located within APOC1, a known major risk gene of AD and blood lipids. Additionally, by applying BGW-TWAS with summary-level GWAS data of AD (N = ∼54K), we identified 13 significant genes including known GWAS risk genes HLA-DRB1 and APOC1, as well as ZC3H12B.


Assuntos
Doença de Alzheimer/genética , Apolipoproteína C-I/genética , Genoma Humano , Modelos Estatísticos , Proteínas/genética , Locos de Características Quantitativas , Ribonucleases/genética , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/metabolismo , Apolipoproteína C-I/metabolismo , Teorema de Bayes , Estudos de Casos e Controles , Simulação por Computador , Feminino , Expressão Gênica , Marcadores Genéticos , Estudo de Associação Genômica Ampla , Cadeias HLA-DRB1/genética , Cadeias HLA-DRB1/metabolismo , Humanos , Masculino , Emaranhados Neurofibrilares/metabolismo , Emaranhados Neurofibrilares/patologia , Proteínas/metabolismo , Ribonucleases/metabolismo , Transcriptoma
12.
Neuroepidemiology ; 54(5): 404-418, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32906123

RESUMO

The Rush Alzheimer's Disease Center (RADC) conducts 5 harmonized prospective clinical-pathologic cohort studies of aging - with 1 study, the Latino Core, focused exclusively on Latinxs, 2 studies consisting of mostly non-Latinx whites, and 2 studies of mostly non-Latinx blacks. This paper contextualizes the Latino Core within the other 4 harmonized RADC cohort studies. The overall aim of the paper is to provide information from the RADC, so that researchers can learn from our participants and procedures to better advance the science of Alzheimer's disease and related dementias in Latinxs. We describe an annual clinical evaluation that assesses risk factors for Alzheimer's dementia among older adults without known dementia at enrollment. As all RADC cohort studies offer brain donation as a part of research participation, we discuss our approach to brain donation and subsequent participant decision-making among older Latinxs. We also summarize baseline characteristics of older Latinxs across the 5 RADC cohort studies in relation to the baseline characteristics of non-Latinx blacks and non-Latinx whites. Finally, we outline challenges and considerations as well as potential next steps in cognitive aging research with older Latinxs.

13.
JBMR Plus ; 4(9): e10390, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32995693

RESUMO

Age-related bone loss is common in older adults. However, the association of low bone mass with incident disability and mortality is not well established. A sample of 738 participants in the Rush Memory and Aging Project (MAP) was evaluated at baseline for bone mineral density (BMD) using quantitative ultrasound at the calcaneus. An annual interview assessed basic activities of daily living (BADL), instrumental activities of daily living (IADL), mobility disability, and history of hip fracture. The associations between baseline BMD and risk of death; incident BADL, IADL, and mobility disability; and hip fracture were investigated using Cox hazard models, adjusting for age, sex, education, race, and body mass index (BMI). The robustness of our findings was evaluated by adjusting for confounding factors and health conditions including joint pain, musculoskeletal medications, smoking status, motor function, global cognition, falls, cardiovascular events, and diabetes. Participants were on average (mean ± SD) 80.9 ± 7.0 years old, 72% female, and 3.8% black, with a baseline BMI of 27.3 ± 5.4 kg/m2, and a baseline of BMD of 0.44 ± 0.14 g/cm2. In models adjusted for age, sex, education, race, and BMI, lower BMD was associated with a higher rate of death (hazard ratio [HR] 1.20; 95% confidence interval [CI], 1.08-1.33), incident BADL disability (HR 1.20; 95% CI, 1.05-1.37), and hip fracture (HR 2.57; 95% CI, 1.72-3.82), but not of IADL disability (HR 1.00; 95% CI, 0.85-1.17) or mobility disability (HR 1.13; 95% CI, 0.97-1.32). The association between BMD and mortality was not significant in fully adjusted models, but the BMD and BADL associations remained significant in models adjusting for both demographic variables and BMD-modifying health conditions. BMD is associated with incident disability in older adults. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

14.
Neurology ; 2020 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-32989103

RESUMO

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, USA. 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 had autopsy. We quantified neuropathology using an index measure of 10 neuropathologic features: ß-amyloid deposition, hippocampal sclerosis, Lewy bodies, tangle density, TDP-43, cerebral amyloid angiopathy, arteriolosclerosis, atherosclerosis, 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's clinical syndrome. Frailty improved the fit of the model for dementia status (χ2(2) = 72.64; p < 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.

15.
Artigo em Inglês | MEDLINE | ID: mdl-32931560

RESUMO

BACKGROUND: Wearable sensors are increasingly employed to quantify diverse aspects of mobility. We developed novel tandem walk (TW) metrics, validated these measures using data from community-dwelling older adults and evaluated their association with mobility disability and measures of gait and postural control. METHODS: 693 community-dwelling older adults (age: 78.69±7.12 yrs) wore a 3D-accelerometer on their lower back while performing three tasks: TW, usual-walking, and quiet standing. Six new measures of TW were extracted from the sensor data along with the clinician's conventional assessment of TW missteps (i.e., trip other loss of balance in which recovery occurred to prevent a fall) and duration. Principal component analysis (PCA) transformed the 6 new TW measures into two summary TW composite factors. Logistic regression models evaluated whether these TW factors were independently associated with mobility disability. RESULTS: Both TW factors were moderately related to the TW conventional measures (r<0.454, p<0.001) and were mildly correlated with usual-walking (r<0.195, p<0.001) and standing, postural control (r<0.119, p<0.001). The TW frequency composite factor (p=0.008), but not TW complexity composite factor (p=0.246), was independently associated with mobility disability in a model controlling for age, sex, body-mass-index, race, conventional measures of TW, and other measures of gait and postural control. CONCLUSIONS: Sensor-derived tandem walk metrics expand the characterization of gait and postural control and suggest that they reflect a relatively independent domain of mobility. Further work is needed to determine if these metrics improve risk stratification for other adverse outcomes (e.g., falls and incident disability) in older adults.

16.
Geroscience ; 42(6): 1431-1443, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32946050

RESUMO

Analysis of skeletal muscle mass and composition is essential for studying the biology of age-related sarcopenia, loss of muscle mass, and function. Muscle immunohistochemistry (IHC) allows for simultaneous visualization of morphological characteristics and determination of fiber type composition. The information gleaned from myosin heavy chain (MHC) isoform, and morphological measurements offer a more complete assessment of muscle health and properties than classical techniques such as SDS-PAGE and ATPase immunostaining; however, IHC quantification is a time-consuming and tedious method. We developed a semiautomatic method to account for issues frequently encountered in aging tissue. We analyzed needle-biopsied vastus lateralis (VL) of the quadriceps from a cohort of 14 volunteers aged 74.9 ± 2.2 years. We found a high correlation between manual quantification and semiautomatic analyses for the total number of fibers detected (r2 = 0.989) and total fiber cross-sectional area (r2 = 0.836). The analysis of the VL fiber subtype composition and the cross-sectional area also did not show statistically significant differences. The semiautomatic approach was completed in 10-15% of the time required for manual quantification. The results from these analyses highlight some of the specific issues which commonly occur in aged muscle. Our methods which address these issues underscore the importance of developing efficient, accurate, and reliable methods for quantitatively analyzing the skeletal muscle and the standardization of collection protocols to maximize the likelihood of preserving tissue quality in older adults. Utilizing IHC as a means of exploring the progression of disease, aging, and injury in the skeletal muscle allows for the practical study of muscle tissue down to the fiber level. By adding editing modules to our semiautomatic approach, we accurately quantified the aging muscle and addressed common technical issues.

17.
J Am Heart Assoc ; 9(18): e017346, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32869681

RESUMO

Background Cardiovascular risk burden has been linked to cardiovascular disease (CVD) and cognitive decline, but its association with disability is unclear. We aimed to examined the association of cardiovascular risk burden assessed by the Framingham general cardiovascular risk score (FGCRS) with the risk and progression of disability and estimated the extent to which CVD and cognitive decline mediate this association. Methods and Results A total of 1480 older adults with no disabilities (mean age=79.32±7.38 years) from the Rush Memory and Aging Project were followed for up to 21 years. FGCRS at baseline was calculated and categorized into tertiles. Disability was assessed annually with activities of daily living. The number of CVDs was calculated by summing up the CVD events. Global cognitive function was assessed annually with a battery of 19 tests. Data were analyzed using the Cox model, linear mixed effects model, and mediation analysis. At the end of the follow-up, 713 (48.2%) participants developed disability. Compared with the lowest tertile of the FGCRS, the multiadjusted hazards ratios of disability were 1.34 (95% CI, 1.11-1.62) for the highest tertile. In addition, the highest FGCRS was associated with a change in activities of daily living score over time (ß=0.057; 95% CI, 0.021-0.093). The association between FGCRS and change in activities of daily living was 13.8% mediated by the accumulation of CVDs and 25.1% by cognitive decline, respectively. Conclusions Higher cardiovascular risk burden increased the risk of disability and accelerated its progression over time. CVD accumulation and cognitive decline may partially mediate the association.

19.
Artigo em Inglês | MEDLINE | ID: mdl-32720690

RESUMO

OBJECTIVE: Mixed-brain pathologies are the most common cause of progressive parkinsonism in older adults. We tested the hypothesis that the impact of individual pathologies associated with progressive parkinsonism, differ among older adults. METHODS: Data was from 1089 decedents who had undergone annual clinical testing and autopsy. Parkinsonism was based on a modified United Parkinson's Disease Rating Scale. Linear mixed-effects models were employed, to investigate the combinations of nine pathologies related to progressive parkinsonism. Then we estimated the person-specific contributions of each pathology for progressive parkinsonism. RESULTS: The average participant showed three pathologies. Parkinson's disease (PD) and four cerebrovascular pathologies [macroinfarcts, atherosclerosis, arteriolosclerosis and cerebral amyloid angiopathy (CAA)] but not AD, TDP-43, hippocampal sclerosis and microinfarcts, were independently associated with progressive parkinsonism. These pathologies accounted for 13% of additional variance of progressive parkinsonism. Thirty-one different combinations of these five pathologies were observed to be associated with progressive parkinsonism observed. On average, PD and CAA accounted respectively for 66% and 65% of person-specific progression of parkinsonism, while macroinfarcts, atherosclerosis and arteriolosclerosis accounted for 41%-48%. CONCLUSION: There is much greater heterogeneity in the comorbidity and relative impact of individual brain pathologies affecting progressive parkinsonism than previously recognized and this may account in part for its phenotypic heterogeneity in older adults.

20.
Nat Sci Sleep ; 12: 299-307, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32581616

RESUMO

Study Objectives: Heart failure has previously been linked to sleep disorders that are often associated with frequent disturbances to human rest/activity patterns. We tested whether fragmentation of sustained rest/activity patterns derived from actigraphic recordings at baseline predicts incident heart failure in community-based elderly individuals. Methods: We studied 1099 community-based elderly adults participating in the Rush Memory and Aging Project who had baseline motor activity monitoring up to 11 days and were followed annually for up to 14 years. Fragmentation was assessed using previously validated indexes, derived from the probability of transitions once sustained rest or activity has been established. Heart failure was recorded via a clinical interview during the annual follow-up. Cox proportional hazards models were constructed to examine the relationship between rest fragmentation index and incident heart failure. Covariates grouped in terms of demographics, lifestyle factors and co-morbidities and cardiovascular risk factors/diseases were included. Results: Increased rest fragmentation (but not activity fragmentation) was associated with higher risk for incident heart failure. Specifically, a subject with a rest fragmentation at the 90th percentile showed a 57% increased risk of developing incident heart failure compared to a subject at the 10th percentile in this cohort. This effect was equivalent to that of being over a decade older. These observations were consistent after adjusting for all covariates. Conclusion: Increased rest fragmentation, a potential surrogate for sleep fragmentation, is independently associated with a higher risk of developing heart failure in community-based elderly adults during up to 14 years of follow-up. Further work is required to examine the specific contributions from daytime napping versus nighttime sleep periods in the elderly, as well as the underlying autonomic and cardio-dynamic pathways that may explain the effects on heart function.

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