OBJECTIVES: The aim of this study was to examine whether perioperative changes in cerebral blood flow (CBF) relate to postoperative neurological deficits in patients undergoing aortic arch surgery... Show moreOBJECTIVES: The aim of this study was to examine whether perioperative changes in cerebral blood flow (CBF) relate to postoperative neurological deficits in patients undergoing aortic arch surgery involving antegrade selective cerebral perfusion (ASCP).METHODS: We retrospectively analysed data from patients who underwent aortic arch surgery involving ASCP and perioperative transcranial Doppler assessments. Linear mixed-model analyses were performed to examine perioperative changes in mean bilateral blood velocity in the middle cerebral arteries, reflecting changes in CBF, and their relation with neurological deficits, i.e. ischaemic stroke and/or delirium. Logistic regression analyses were performed to explore possible risk factors for postoperative neurological deficits.RESULTS: In our study population (N = 102), intraoperative blood velocities were lower compared to preoperative levels, and lowest during ASCP. Thirty-six (35%) patients with postoperative neurological deficits (ischaemic stroke, n = 9; delirium, n = 25; both, n = 2) had lower blood velocity during ASCP compared to patients without (25.4 vs 37.0 cm/s; P = 0.002). Logistic regression analyses revealed lower blood velocity during ASCP as an independent risk factor for postoperative neurological deficits (odds ratio = 0.959; 95% confidence interval: 0.923, 0.997; P = 0.037).CONCLUSIONS: Lower intraoperative CBF during ASCP seems independently related to postoperative neurological deficits in patients undergoing aortic arch surgery. Because CBF is a modifiable factor during ASCP, our observation has significant potential to improve clinical management and prevent neurological deficits. Show less
Wang, L.P.; Pronk, A.C.; Poelgeest, E.P. van; Briggs, R.; Claassen, J.A.H.R.; Jansen, S.; ... ; Velde, N. van der 2023
Orthostatic hypotension (OH) is an established and common cardiovascular risk factor for falls. An in-depth understanding of the various interacting pathophysiological pathways contributing to OH... Show moreOrthostatic hypotension (OH) is an established and common cardiovascular risk factor for falls. An in-depth understanding of the various interacting pathophysiological pathways contributing to OH-related falls is essential to guide improvements in diagnostic and treatment opportunities. We applied systems thinking to multidisciplinary map out causal mechanisms and risk factors. For this, we used group model building (GMB) to develop a causal loop diagram (CLD). The GMB was based on the input of experts from multiple domains related to OH and falls and all proposed mechanisms were supported by scientific literature. Our CLD is a conceptual representation of factors involved in OH-related falls, and their interrelatedness. Network analysis and feedback loops were applied to analyze and interpret the CLD, and quantitatively summarize the function and relative importance of the variables. Our CLD contains 50 variables distributed over three intrinsic domains (cerebral, cardiovascular, and musculoskeletal), and an extrinsic domain (e.g., medications). Between the variables, 181 connections and 65 feedback loops were identified. Decreased cerebral blood flow, low blood pressure, impaired baroreflex activity, and physical inactivity were identified as key factors involved in OH-related falls, based on their high centralities. Our CLD reflects the multifactorial pathophysiology of OH-related falls. It enables us to identify key elements, suggesting their potential for new diagnostic and treatment approaches in fall prevention. The interactive online CLD renders it suitable for both research and educational purposes and this CLD is the first step in the development of a computational model for simulating the effects of risk factors on falls. Show less
Mofrad, R.B.; Campo, M. del; Peeters, C.F.W.; Meeter, L.H.H.; Seelaar, H.; Koel-Simmelink, M.; ... ; Teunissen, C.E. 2022
Background Frontotemporal dementia (FTD) is caused by frontotemporal lobar degeneration (FTLD), characterized mainly by inclusions of Tau (FTLD-Tau) or TAR DNA binding43 (FTLD-TDP) proteins. Plasma... Show moreBackground Frontotemporal dementia (FTD) is caused by frontotemporal lobar degeneration (FTLD), characterized mainly by inclusions of Tau (FTLD-Tau) or TAR DNA binding43 (FTLD-TDP) proteins. Plasma biomarkers are strongly needed for specific diagnosis and potential treatment monitoring of FTD. We aimed to identify specific FTD plasma biomarker profiles discriminating FTD from AD and controls, and between FTD pathological subtypes. In addition, we compared plasma results with results in post-mortem frontal cortex of FTD cases to understand the underlying process. Methods Plasma proteins (n = 1303) from pathologically and/or genetically confirmed FTD patients (n = 56; FTLD-Tau n = 16; age = 58.2 +/- 6.2; 44% female, FTLD-TDP n = 40; age = 59.8 +/- 7.9; 45% female), AD patients (n = 57; age = 65.5 +/- 8.0; 39% female), and non-demented controls (n = 148; 61.3 +/- 7.9; 41% female) were measured using an aptamer-based proteomic technology (SomaScan). In addition, exploratory analysis in post-mortem frontal brain cortex of FTD (n = 10; FTLD-Tau n = 5; age = 56.2 +/- 6.9, 60% female, and FTLD-TDP n = 5; age = 64.0 +/- 7.7, 60% female) and non-demented controls (n = 4; age = 61.3 +/- 8.1; 75% female) were also performed. Differentially regulated plasma and tissue proteins were identified by global testing adjusting for demographic variables and multiple testing. Logistic lasso regression was used to identify plasma protein panels discriminating FTD from non-demented controls and AD, or FTLD-Tau from FTLD-TDP. Performance of the discriminatory plasma protein panels was based on predictions obtained from bootstrapping with 1000 resampled analysis. Results Overall plasma protein expression profiles differed between FTD, AD and controls (6 proteins; p = 0.005), but none of the plasma proteins was specifically associated to FTD. The overall tissue protein expression profile differed between FTD and controls (7-proteins; p = 0.003). There was no difference in overall plasma or tissue expression profile between FTD subtypes. Regression analysis revealed a panel of 12-plasma proteins discriminating FTD from AD with high accuracy (AUC: 0.99). No plasma protein panels discriminating FTD from controls or FTD pathological subtypes were identified. Conclusions We identified a promising plasma protein panel as a minimally-invasive tool to aid in the differential diagnosis of FTD from AD, which was primarily associated to AD pathophysiology. The lack of plasma profiles specifically associated to FTD or its pathological subtypes might be explained by FTD heterogeneity, calling for FTD studies using large and well-characterize cohorts. Show less
Research links high blood pressure variability (BPV) with stroke and cerebrovascular disease, however, its association with cognition remains unclear. Moreover, it remains uncertain which BP... Show moreResearch links high blood pressure variability (BPV) with stroke and cerebrovascular disease, however, its association with cognition remains unclear. Moreover, it remains uncertain which BP-derived parameter (ie, variability or mean) holds more significance in understanding vascular contributions to cognitive impairment. We searched PubMed, Embase, PsycINFO, and Scopus and performed a meta-analysis of studies that quantified the association between resting BPV with dementia or cognitive impairment in adults. Two authors independently reviewed all titles, abstracts, and full-texts and extracted data, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-Analysis of Observational Studies in Epidemiology guidelines. Study quality was assessed using the (modified) Newcastle-Ottawa Scale. A multilevel meta-analysis was used, which included effect sizes for both BPV and mean BP, with a combined end point of dementia or cognitive impairment as primary outcome. In the primary analysis, 54 effect sizes were extracted from 20 studies, with a total analytical sample of n=7 899 697. Higher systolic BPV (odds ratio [OR], 1.25 [95% CI, 1.16-1.35]), mean systolic pressure (OR, 1.12 [95% CI, 1.02-1.29]), diastolic BPV (OR, 1.20 [95% CI, 1.12-1.29]), and mean diastolic pressure (OR, 1.16 [95% CI, 1.04-1.29]) were associated with dementia and cognitive impairment. A direct comparison showed that mean BP effect sizes were less strong than BPV effect sizes (OR, 0.92 [95% CI, 0.87-0.97], P<0.01), indicating that the relative contribution of BPV exceeded that of mean BP. Methodological and statistical heterogeneity was high. Secondary analyses were less consistent as to whether BPV and mean BP were differentially associated with dementia subtypes and cognitive domains. Future studies are required to investigate BPV as a target for dementia prevention. Show less
Bron, E.E.; Klein, S.; Papma, J.M.; Jiskoot, L.C.; Venkatraghavan, V.; Linders, J.; ... ; Lugt, A. van der 2021
This work validates the generalizability of MRI-based classification of Alzheimer's disease (AD) patients and controls (CN) to an external data set and to the task of prediction of conversion to AD... Show moreThis work validates the generalizability of MRI-based classification of Alzheimer's disease (AD) patients and controls (CN) to an external data set and to the task of prediction of conversion to AD in individuals with mild cognitive impairment (MCI). We used a conventional support vector machine (SVM) and a deep convolutional neural network (CNN) approach based on structural MRI scans that underwent either minimal pre-processing or more extensive preprocessing into modulated gray matter (GM) maps. Classifiers were optimized and evaluated using cross validation in the Alzheimer's Disease Neuroimaging Initiative (ADNI; 334 AD, 520 CN). Trained classifiers were subsequently applied to predict conversion to AD in ADNI MCI patients (231 converters, 628 non converters) and in the independent Health-RI Parelsnoer Neurodegenerative Diseases Biobank data set. From this multi-center study representing a tertiary memory clinic population, we included 199 AD patients, 139 participants with subjective cognitive decline, 48 MCI patients converting to dementia, and 91 MCI patients who did not convert to dementia. AD-CN classification based on modulated GM maps resulted in a similar area-under-the-curve (AUC) for SVM (0.940; 95%CI: 0.924-0.955) and CNN (0.933; 95%CI: 0.918-0.948). Application to conversion prediction in MCI yielded significantly higher performance for SVM (AUC = 0.756; 95%CI: 0.720-0.788) than for CNN (AUC = 0.742; 95%CI: 0.709-0.776) (p < 0.01 for McNemar's test). In external validation, performance was slightly decreased. For AD-CN, it again gave similar AUCs for SVM (0.896; 95%CI: 0.855-0.932) and CNN (0.876; 95%CI: 0.836-0.913). For prediction in MCI, performances decreased for both SVM (AUC = 0.665; 95%CI: 0.576-0.760) and CNN (AUC = 0.702; 95%CI: 0.624-0.786). Both with SVM and CNN, classification based on modulated GM maps significantly outperformed classification based on minimally processed images (p = 0.01). Deep and conventional classifiers performed equally well for AD classification and their performance decreased only slightly when applied to the external cohort. We expect that this work on external validation contributes towards translation of machine learning to clinical practice. Show less
Objectiv(e): To investigate the relationship between Alzheimer's disease biomarkers and neuropsychiatric symptoms. Methods: Data from two large cohort studies, the Dutch Parelsnoer Institute -... Show moreObjectiv(e): To investigate the relationship between Alzheimer's disease biomarkers and neuropsychiatric symptoms. Methods: Data from two large cohort studies, the Dutch Parelsnoer Institute - Neurodegenerative Diseases and the Alzheimer's Disease Neuroimaging Initiative was used, including subjects with subjective cognitive decline (N= 650), mild cognitive impairment (N = 887), and Alzheimer's disease dementia (N = 626). Cerebrospinal fluid (CSF) levels of A beta(42), t-tau, p-tau, and hippocampal volume were associated with neuropsychiatric symptoms (measured with the Neuropsychiatric Inventory) using multiple logistic regression analyses. The effect of the Mini-Mental State Examination (as proxy for cognitive functioning) on these relationships was assessed with mediation analyses. Results: Alzheimer's disease biomarkers were not associated with depression, agitation, irritability, and sleep disturbances. Lower levels of CSF A beta(42), higher levels of t- and p-tau were associated with presence of anxiety. Lower levels of CSF A beta(42) and smaller hippocampal volumes were associated with presence of apathy. All associations were mediated by cognitive functioning. Conclusion: The association between Alzheimer's disease pathology and anxiety and apathy is partly due to impairment in cognitive functioning. Show less
BackgroundResearch links blood pressure variability (BPV) with stroke; however, the association with cerebral small-vessel disease (CSVD) remains unclear. As BPV and mean blood pressure are... Show moreBackgroundResearch links blood pressure variability (BPV) with stroke; however, the association with cerebral small-vessel disease (CSVD) remains unclear. As BPV and mean blood pressure are interrelated, it remains uncertain whether BPV adds additional information to understanding cerebrovascular morphological characteristics.Methods and ResultsA systematic review was performed from inception until March 3, 2019. Eligibility criteria included population, adults without stroke (<4 weeks); exposure, BPV quantified by any metric over any duration; comparison, (1) low versus high or mean BPV and (2) people with versus without CSVD; and outcomes, (1) CSVD as subcortical infarct, lacunae, white matter hyperintensities, cerebral microbleeds, or enlarged perivascular spaces; and (2) standardized mean difference in BPV. A total of 27 articles were meta-analyzed, comprising 12 309 unique brain scans. A total of 31 odds ratios (ORs) were pooled, indicating that higher systolic BPV was associated with higher odds for CSVD (OR, 1.27; 95% CI, 1.14-1.42; I-2=85%) independent of mean systolic pressure. Likewise, higher diastolic BPV was associated with higher odds for CSVD (OR, 1.30; 95% CI, 1.14-1.48; I-2=53%) independent of mean diastolic pressure. There was no evidence of a pairwise interaction between systolic/diastolic and BPV/mean ORs (P=0.47), nor a difference between BPV versus mean pressure ORs (P=0.58). Fifty-four standardized mean differences were pooled and provided similar results for pairwise interaction (P=0.38) and difference between standardized mean differences (P=0.70).ConclusionsOn the basis of the available studies, BPV was associated with CSVD independent of mean blood pressure. However, more high-quality longitudinal data are required to elucidate whether BPV contributes unique variance to CSVD morphological characteristics. Show less
Cerebrovascular changes, including reduced cerebral blood flow (CBF), occur early in the development of Alzheimer disease and may accelerate disease progression. This randomized, double-blind,... Show moreCerebrovascular changes, including reduced cerebral blood flow (CBF), occur early in the development of Alzheimer disease and may accelerate disease progression. This randomized, double-blind, placebo-controlled study investigated how 6 months of treatment with the calcium antagonist nilvadipine would affect CBF in patients with mild-to-moderate Alzheimer disease. CBF was measured with magnetic resonance arterial spin labeling in whole-brain gray matter and in a priori defined regions of interest including the hippocampus. Fifty-eight patients were randomly assigned (29 in each group), of whom 22 in both groups had no magnetic resonance exclusion criteria and were medication compliant over 6 months. Mean age was 72.8 +/- 6.2 years, mean mini-mental state examination was 20.4 +/- 3.4. Nilvadipine treatment lowered systolic blood pressure (Delta=-11.5 [95% CI, -19.7 to -3.2] mm Hg; P<0.01), while whole-brain gray-matter CBF remained stable (Delta=5.4 [95% CI, -6.4 to 17.2] mL/100 g per minute; P=0.36). CBF in the hippocampus increased (left: Delta=24.4 [95% CI, 4.3-44.5] mL/100 g per minute; P=0.02; right: Delta=20.1 [95% CI, -0.6 to 40.8] mL/100 g per minute; P=0.06). There was no significant change in CBF in the posterior cingulate cortex (Delta=5.2 [95% CI, -16.5 to 27.0] mL/100 g per minute; P=0.63) or other regions of interest. In conclusion, nilvadipine reduced blood pressure and increased CBF in the hippocampus, whereas other regions showed stable or small nonsignificant increases in CBF. These findings not only indicate preserved cerebral autoregulation in Alzheimer disease but also point toward beneficial cerebrovascular effects of antihypertensive treatment. Show less
