Clinically asymptomatic vascular brain injury: a potent cause of cognitive impairment among older individuals

Mechanical behavior and microstructure of porcine brain tissues under pulsed electric fields

Pulsed electric fields are extensively utilized in clinical treatments, such as subthalamic deep brain stimulation, where electric field loading is in direct contact with brain tissue. However, the alterations in brain tissue's mechanical properties and microstructure due to changes in electric field parameters have not received adequate attention. In this study, the mechanical properties and microstructure of the brain tissue under pulsed electric fields were focused on. Herein, a custom indentation device was equipped with a module for electric field loading. Parameters such as pulse amplitude and frequency were adjusted. The results demonstrated that following an indentation process lasting 5 s and reaching a depth of 1000 μm, and a relaxation process of 175 s, the average shear modulus of brain tissue was reduced, and viscosity decreased. At the same amplitude, high-frequency pulsed electric fields had a smaller effect on brain tissue than low-frequency ones. Furthermore, pulsed electric fields induced cell polarization and reduced the proteoglycan concentration in brain tissue. As pulse frequency increased, cell polarization diminished, and proteoglycan concentration decreased significantly. High-frequency pulsed electric fields applied to brain tissue were found to reduce impedance fluctuation amplitude. This study revealed the effect of pulsed electric fields on the mechanical properties and microstructure of ex vivo brain tissue, providing essential information to promote the advancement of brain tissue electrotherapy in clinical settings.

Irreversible postoperative cognitive impairment after unruptured intracranial aneurysm treatment in the elderly

PURPOSE

Postoperative cognitive dysfunction and recovery remain unclear in older patients undergoing interventional therapies for unruptured intracranial aneurysms (UIAs). This study aimed to compare changes in postoperative cognitive function between younger and older patients and to detect factors associated with non-recovery from postoperative cognitive dysfunction.

METHODS

This study reviewed 59 consecutive patients with UIAs who underwent interventional therapies, including microsurgical clipping or endovascular treatment, from 2021 to 2022. All patients were divided into the older (aged ≥ 70 years) and younger (aged < 70 years) groups. Mini-Mental State Examination (MMSE) and Frontal Assessment Battery (FAB) were performed within 2 months before interventions, at 1 week postoperatively (POW1), and 3-6 months postoperatively (POM3-6).

RESULTS

MMSE and FAB scores decreased more frequently in the older group than in the younger group at POW1 (older vs. younger: MMSE: 48% vs. 21%, p < 0.05; FAB: 56% vs. 18%, p < 0.01). In the older group, the FAB Z-score decreased in POW1 and recovered by POM3-6 (p < 0.01), while the MMSE Z-score continued to decrease (p = 0.04). Age and the preoperative MSME Z-score were significantly associated with non-recovery from decreased MMSE score at POM3-6 (recovery vs. non-recovery, age: 62 years old vs. 72 years old, p = 0.03, preoperative MMSE Z-score: 0.16 vs. - 0.90, p < 0.01).

CONCLUSIONS

This retrospective study found that older patients were more likely to have a postoperative cognitive decline after UIA treatment and implicated that global cognitive function tended to decline more than executive function in the long term. In addition, this study demonstrated that lower preoperative cognitive function was associated with inadequate postoperative cognitive recovery. The findings potentially contribute to the establishment of indications for treating UIAs in older patients.

White matter hyperintensities in diverse populations: A systematic review of literature in the United States

As the United States' (US) elderly population becomes increasingly diverse, it is imperative that research studies address cognitive health in diverse populations of older Americans. White Matter Hyperintensities (WMH) are useful imaging findings that can be studied in elderly individuals and have been linked to an increased risk of neurological conditions, such as stroke, cognitive impairment, and dementia. We performed a systematic review of literature using PubMed sources to compile all the studies that investigated the prevalence of ethnic and racial differences of WMH burden amongst diverse groups in the US. We identified 23 unique articles that utilized 16 distinct cohorts of which 94 % were prospective, longitudinal studies that included community-based and family-based populations. The overall results were heterogenous in all aspects of data collection and analysis, limiting our ability to run meta-analyses and draw definitive conclusions. General observations suggest increased vascular risk on African American populations, contributing to greater WMH burden in that population. Overall, the findings of this study indicate a need for a standardized approach to investigating WMH in efforts to measure its clinical impact on diverse populations.

Body Mass Index, White Matter Hyperintensities, and Cognitive Performance in American Indians: Data from the Strong Heart Study

BACKGROUND

Previous studies report that obesity can be a risk and a protective factor for cognitive health. However, they have not examined whether white matter hyperintensities (WMH) mediate the association between mid- or late-life body mass index (BMI) and late-life cognitive performance. We examined this question in American Indians, a population underrepresented in neuropsychological research.

METHOD

We used longitudinal data from the cerebrovascular disease and its consequences in American Indians (n = 817), with BMI data collected at midlife (1989-91) and lat-life (2010-13). Cognitive data were collected in late life, with tests for general cognition, processing speed, verbal fluency, and memory. Neuroradiologist-scored WMH severity and volume using standard analysis pipelines. We examined associations among BMI, WMH severity and volume, and cognitive scores using linear regression and the Baron and Kenny method to estimate mediation.

RESULT

High BMI in late life was associated with a 1.79-point higher score in general cognition (95% CI 0.63-2.95, p-value = 0.002), but not the other tests. Mediated by WMH severity, high late-life BMI was associated with a 1.53-point higher score in general cognition (95% CI 0.37-2.69) and, by WMH volume, 1.63 points higher (95% CI 0.49-2.77). The association between late-life obesity and cognitive performance is stronger for females (β = 1.74, 95% CI 0.35-3.13, p-value = 0.014) than for males (β = 1.66, 95% CI -0.63-3.95, p-value = 0.158).

CONCLUSION

In American Indians, high late-life BMI was positively associated with cognitive performance, with a stronger association for females. WMH severity and volume partly attenuate these associations.

Acute Myocardial Infarction and Risk of Cognitive Impairment and Dementia: A Review

Cognitive impairment (CI) shares common cardiovascular risk factors with acute myocardial infarction (AMI), and is increasingly prevalent in our ageing population. Whilst AMI is associated with increased rates of CI, CI remains underreported and infrequently identified in patients with AMI. In this review, we discuss the evidence surrounding AMI and its links to dementia and CI, including pathophysiology, risk factors, management and interventions. Vascular dysregulation plays a major role in CI, with atherosclerosis, platelet activation, microinfarcts and perivascular inflammation resulting in neurovascular unit dysfunction, disordered homeostasis and a dysfunctional neurohormonal response. This subsequently affects perfusion pressure, resulting in enlarged periventricular spaces and hippocampal sclerosis. The increased platelet activation seen in coronary artery disease (CAD) can also result in inflammation and amyloid-β protein deposition which is associated with Alzheimer's Dementia. Post-AMI, reduced blood pressure and reduced left ventricular ejection fraction can cause chronic cerebral hypoperfusion, cerebral infarction and failure of normal circulatory autoregulatory mechanisms. Patients who undergo coronary revascularization (percutaneous coronary intervention or bypass surgery) are at increased risk for post-procedure cognitive impairment, though whether this is related to the intervention itself or underlying cardiovascular risk factors is debated. Mortality rates are higher in dementia patients with AMI, and post-AMI CI is more prevalent in the elderly and in patients with post-AMI heart failure. Medical management (antiplatelet, statin, renin-angiotensin system inhibitors, cardiac rehabilitation) can reduce the risk of post-AMI CI; however, beta-blockers may be associated with functional decline in patients with existing CI. The early identification of those with dementia or CI who present with AMI is important, as subsequent tailoring of management strategies can potentially improve outcomes as well as guide prognosis.

Diffusion-weighted imaging lesions after endovascular treatment of cerebral aneurysms: A network meta-analysis

Background

Thromboembolism is one of the common complications in endovascular treatments including coiling alone, stent-assisted coiling (SAC), balloon-assisted coiling (BAC), and flow-diverting (FD) stents. Such treatments are widely used in intracranial aneurysms (IAs), which usually present as positive lesions in diffusion-weighted imaging (DWI). Whether these adjunctive techniques increase postprocedural DWI-positive lesions after endovascular treatment remains unclear.

Methods

A thorough electronic search for the literature published in English between January 2000 and October 2022 was conducted on PubMed, Medline, and EMBASE. Eighteen studies (3 cohort studies and 15 case-control studies) involving 1,843 patients with unruptured IAs (UIAs) were included. We performed a frequentist framework network meta-analysis (NMA) to compare the rank risks of cerebral thromboembolism of the above four endovascular treatments. The incoherence test was used to analyze the statistical disagreement between direct and indirect evidence. Funnel plots were used to analyze publication bias.

Results

The incidences of DWI lesions in patients who received FD stents, SAC, BAC, and coiling alone were 66.1% (109/165), 37.6% (299/795), 31.1% (236/759), and 25.6% (236/921). The incidence of DWI lesions in patients who received FD stents was higher than that in patients who received SAC [OR: 2.40; 95% CI (1.15, 5.00), P < 0.05], BAC [OR: 2.62; 95% CI (1.19, 5.77), P < 0.05], or coiling alone [OR: 2.77; 95% CI (1.26, 6.07), P < 0.05]. The incoherence test showed preferable consistency in this NMA. No obvious publication bias was found in the funnel plot.

Conclusion

FD stent placement brings more ischemic lesions identified by DWI than any other procedures for patients with UIA. The characteristics of FD stents may result in a high incidence of DWI lesions.

Association of Stroke and Cerebrovascular Pathologies With Scam Susceptibility in Older Adults

Importance

Scam susceptibility is associated with adverse financial and health outcomes, including an increased risk of cognitive decline and dementia. Very little is known about the role of cerebrovascular pathologies with scam susceptibility.

Objective

To examine the association of diverse cerebrovascular pathologies (globally and regionally) with scam susceptibility.

Design, setting, and Participants

This clinical-pathological cohort study included participants from 2 ongoing studies of aging that began enrollment in 1994 and 1997. In 2010, participants were enrolled in the decision-making and behavioral economics substudy and were followed up for a mean (SD) of 3.4 (2.6) years prior to death. From 1365 older persons with clinical evaluations, 69 were excluded for having dementia at baseline. From 538 older persons who died, 408 had annual assessments for scam susceptibility, cardiovascular risk burden, and cognitive function and consented to brain donation for detailed neuropathologic examination. Data were analyzed from June 2021 through September 2022.

Exposures

Neuropathologic examination identified the presence of macroscopic and microscopic infarcts, atherosclerosis, arteriolosclerosis, cerebral amyloid angiopathy, and common neurodegenerative pathologies (Alzheimer disease, limbic-predominant age-related transactive response DNA-binding protein 43 encephalopathy, and Lewy bodies).

Results

There was a total of 408 participants. The mean (SD) age at death was 91 (6.1) years, the mean (SD) amount of education was 15.6 (3.1) years, and 297 (73%) were women. Participants included 4 Latino individuals (1%), 7 non-Latino Black individuals (2%), and 397 non-Latino White individuals (97%). The frequency of participants with macroscopic infarcts was 38% (n = 154), microinfarcts was 40% (n = 163), and moderate to severe vessel disease; specifically, atherosclerosis was 20% (n = 83), arteriolosclerosis was 25% (n = 100), and cerebral amyloid angiopathy was 35% (n = 143). In linear regression models adjusted for demographics and neurodegenerative pathologies, macroscopic infarcts were associated with greater scam susceptibility (estimate [SE], 0.18 [0.07]; P = .009). This association persisted after adjusting for cardiovascular risk burden and global cognition. Regionally, infarcts localized to the frontal, temporal, and occipital lobes and thalamus were associated with greater scam susceptibility. Neither arteriosclerosis, atherosclerosis, cerebral amyloid angiopathy, nor microinfarcts were associated with scam susceptibility.

Conclusions and Relevance

Cerebrovascular pathologies, specifically cerebral infarcts, is linked with greater scam susceptibility in older adults, independent of common neurodegenerative diseases such as Alzheimer disease. Future studies examining in vivo magnetic resonance imaging markers of cerebrovascular pathologies with scam susceptibility and related decision-making outcomes will be important.

The safety and efficacy of the Mo.Ma system device for carotid artery stenting: A single-center experience from Taiwan

Background

Proximal protection devices, such as the Mo.Ma system provides better neurological outcomes than the distal filter system in the carotid artery stenting (CAS) procedure. This study first evaluated the safety and efficacy of the Mo.Ma system during CAS in a single tertiary referral hospital from Taiwan. The outcomes of distal vs. proximal embolic protection devices were also studied.

Methods

A total of 294 patients with carotid artery stenosis who underwent the CAS procedure were retrospectively included and divided into two groups: 152 patients in the distal filter system group and 142 patients in the Mo.Ma system. The outcomes of interest were compared between the two groups. The factors contributing to occlusion intolerance (OI) in the Mo.Ma system were evaluated.

Results

The procedure success rates were more than 98% in both groups. No major stroke occurred in this study. The minor stroke rates were 2.8% (4/142) and 4.6% (7/152) in the Mo.Ma system and filter system, respectively (p = 0.419). Patients with hypoalbuminemia significantly predicted the risk of stroke with an odds ratio of 0.08 [95% confidence interval (CI), 0.01–0.68, p = 0.020] per 1 g/day of serum albumin in the filter group. A total of 12 patients developed OI in the Mo.Ma system (12/142, 8%). Low occlusion pressure predicted the occurrence of OI in the Mo.Ma group with the hazard ratios of 0.88 (95% CI: 0.82–0.96) and 0.90 (95% CI: 0.84–0.98) per 1 mmHg of occlusion systolic pressure (OSP) and diastolic pressure (ODP), respectively. We further indicated that patients with an OSP of ≥60 mmHg or an ODP of ≥44 mmHg could tolerate the procedure of occlusion time up to 400 s, while patients with an OSP of <49 mmHg or an ODP of <34 mmHg should undergo the procedure of occlusion time less than 300 s to prevent the occurrence of OI.

Conclusion

We have demonstrated the safety and effectiveness of the Mo.Ma system during CAS in an Asia population. By reducing the occlusion time, our study indicated a lower risk of OI in the Mo.Ma system and proposed the optimal occlusion time according to occlusion pressure to prevent OI during the CAS procedure. Further large-scale and prospective studies are needed to verify our results.

Imaging Markers of Vascular Brain Health: Quantification, Clinical Implications, and Future Directions

Cerebrovascular disease (CVD) manifests through a broad spectrum of mechanisms that negatively impact brain and cognitive health. Oftentimes, CVD changes (excluding acute stroke) are insufficiently considered in aging and dementia studies which can lead to an incomplete picture of the etiologies contributing to the burden of cognitive impairment. Our goal with this focused review is 3-fold. First, we provide a research update on the current magnetic resonance imaging methods that can measure CVD lesions as well as early CVD-related brain injury specifically related to small vessel disease. Second, we discuss the clinical implications and relevance of these CVD imaging markers for cognitive decline, incident dementia, and disease progression in Alzheimer disease, and Alzheimer-related dementias. Finally, we present our perspective on the outlook and challenges that remain in the field. With the increased research interest in this area, we believe that reliable CVD imaging biomarkers for aging and dementia studies are on the horizon.

Sequence of Alzheimer disease biomarker changes in cognitively normal adults: A cross-sectional study

OBJECTIVE

To determine the ordering of changes in Alzheimer disease (AD) biomarkers among cognitively normal individuals.

METHODS

Cross-sectional data, including CSF analytes, molecular imaging of cerebral fibrillar β-amyloid (Aβ) with PET using the [11C] benzothiazole tracer Pittsburgh compound B (PiB), MRI-based brain structures, and clinical/cognitive outcomes harmonized from 8 studies, collectively involving 3,284 cognitively normal individuals 18 to 101 years of age, were analyzed. The age at which each marker exhibited an accelerated change (called the change point) was estimated and compared across the markers.

RESULTS

Accelerated changes in CSF Aβ1-42 (Aβ42) occurred at 48.28 years of age and in Aβ42/Aβ40 ratio at 46.02 years, followed by PiB mean cortical standardized uptake value ratio (SUVR) with a change point at 54.47 years. CSF total tau (Tau) and tau phosphorylated at threonine 181 (Ptau) had a change point at ≈60 years, similar to those for MRI hippocampal volume and cortical thickness. The change point for a cognitive composite occurred at 62.41 years. The change points for CSF Aβ42 and Aβ42/Aβ40 ratio, albeit not significantly different from that for PiB SUVR, occurred significantly earlier than that for CSF Tau, Ptau, MRI markers, and the cognitive composite. Adjusted analyses confirmed that accelerated changes in CSF Tau, Ptau, MRI markers, and the cognitive composite occurred at ages not significantly different from each other.

CONCLUSIONS

Our findings support the hypothesized early changes of amyloid in preclinical AD and suggest that changes in neuronal injury and neurodegeneration markers occur close in time to cognitive decline.

Association of vascular brain injury, neurodegeneration, amyloid, and cognitive trajectory

OBJECTIVE

To determine whether vascular and neurodegenerative factors influence cognition before clinically relevant Alzheimer disease pathology, we analyzed MRI measures and amyloid imaging in an ethnoracially diverse cohort of cognitively normal individuals older than 60 years.

METHODS

Participants (n = 154; mean age 74.15 ± 6.94; 50% female; 54% Caucasian, 22.1% Hispanic, 14.9% African American) were recruited from the University of California, Davis Alzheimer's Disease Research Center, who were cognitively normal at baseline, time of PET, and MRI, and received yearly cognitive assessment for 6.23 ± 4.16 years. Mixed model regression with random slope and intercept was calculated for episodic memory and executive function, adjusting for age, sex, education, and ethnicity.

RESULTS

Vascular burden score was associated with total white matter hyperintensity (WMH) volume (β, 0.171; 95% confidence interval [CI], 0.024-0.318). WMH volume was associated with low baseline executive function (-0.115; -0.226 to -0.003) and rate of change in memory (-0.029; -0.045 to -0.012). Hippocampal volume was associated with the rate of change in memory (0.040; 0.021-0.059) and executive function (0.024; 0.008-0.039). Continuous measures of amyloid status influenced change in memory (-0.026; -0.044 to -0.008) and executive function (-0.033; -0.046 to -0.021) independently of MRI measures.

CONCLUSION

Vascular brain injury and neurodegeneration are associated with baseline cognitive performance and the rate of longitudinal change independent of amyloid status among community-dwelling, ethnicity diverse cognitively normal individuals, supporting the role of vascular diseases as risk factors for later-life dementia.

Vascular Burden Score Impacts Cognition Independent of Amyloid PET and MRI Measures of Alzheimer's Disease and Vascular Brain Injury

BACKGROUND/OBJECTIVE

To determine the impact of vascular burden on rates of decline in episodic memory and executive function. We hypothesize that greater vascular burden will have an additive negative impact on cognition after accounting for baseline cognitive impairment, positron emission tomography (PET) amyloid burden, and magnetic resonance imaging (MRI) measures.

METHODS

Individuals were followed an average of 5 years with serial cognitive assessments. Predictor variables include vascular burden score (VBS), quantitative brain MRI assessment, and amyloid imaging. Subjects consisted of 65 individuals, 53% of whom were male, aged 73.2±7.2 years on average with an average of 15.5±3.3 years of educational achievement.

RESULTS

Baseline cognitive impairment was significantly associated poorer episodic memory (p < 0.0001), smaller hippocampal volume (p < 0.0001), smaller brain volume (p = 0.0026), and greater global Pittsburg Imaging Compound B (PiB) index (p = 0.0008). Greater amyloid burden was associated with greater decline in episodic memory over time (β= -0.20±0.07, p < 0.005). VBS was significantly associated with the level of executive function performance (β= -0.14±0.05, p < 0.005) and there was a significant negative interaction between VBS, cognitive impairment, and PiB index (β= -0.065±0.03, p = 0.03).

CONCLUSIONS

Our results find a significant influence of VBS independent of standard MRI measures and cerebral amyloid burden on executive function. In addition, VBS reduced the amount of cerebral amyloid burden needed to result in cognitive impairment. We conclude that the systemic effects of vascular disease as reflected by the VBS independently influence cognitive ability.

Objective short sleep duration increases the risk of all-cause mortality associated with possible vascular cognitive impairment

OBJECTIVES

Cognitive impairment is a leading cause of disability worldwide, and cardiometabolic conditions are key contributors to its development. Short sleep is also a potential contributor to brain health; however, its role in predicting mortality remains poorly understood. We investigated whether objective short sleep duration increases the risk of all-cause mortality associated with coexisting cognitive impairment and cardiometabolic conditions, i.e., possible vascular cognitive impairment (VCI).

DESIGN

This is a longitudinal study.

SETTING

This is a population-based, in-lab study.

PARTICIPANTS

A total of 1,524 adults (aged 48.9±13.4 years, 53.4% women) from the Penn State Adult Cohort were included in the study.

MEASUREMENTS

All-cause mortality was estimated after 19.1±5.1 years of follow-up. Neuropsychological testing was performed to ascertain cognitive impairment. Clinical history and physical examination were performed to ascertain stage 2 hypertension, type 2 diabetes, heart disease, and stroke. Possible VCI was defined as the presence of any of these cardiometabolic conditions and cognitive impairment. In-lab, 8-hour polysomnography (PSG) was performed to ascertain short sleep duration (i.e., <6 hours).

RESULTS

Multivariable-adjusted Cox proportional-hazard models showed that the risk of all-cause mortality associated with cardiometabolic conditions (n=864) and possible VCI (n=122) was significantly increased in those who slept <6 hours at baseline (hazards ratio [HR] = 1.79, 95% confidence interval [CI] = 1.28-2.51 and HR = 4.01, 95% CI = 2.66-6.05, respectively), while it was negligible in those who slept ≥6 hours (HR = 1.44, 95% CI = 0.99-2.09 and HR = 1.41, 95% CI = 0.70-2.83, respectively).

CONCLUSIONS

Objective short sleep duration predicts the mortality prognosis of adults with possible VCI. Sleep duration and cognition should be objectively evaluated in patients presenting with a cluster of cardiometabolic conditions and sleep and cognitive complaints. Short sleep is a useful risk factor in the prediction of adverse cardiometabolic and brain health outcomes.

"Liquid Biopsy" of White Matter Hyperintensity in Functionally Normal Elders

Background and Objective: In the aging brain, increased blood-brain barrier (BBB) leakage and white matter hyperintensity (WMH) on MRI are frequently presumed secondary to cerebral small vessel disease (cSVD) or endotheliopathy. We investigate this association in vivo by quantifying protein cargo from endothelial-derived exosomes (EDE), and comparing levels between two groups of functionally normal elders with and without WMH. In addition, we study associations of EDE proteins with upstream and downstream factors, such as inflammation and neurodegenerative changes, respectively.

Methods: Twenty six neurologically normal older adults completed general health questionnaires, neuropsychological and physical examinations, and brain MRI. WMH was visually graded with modified Fazekas score of 2 or greater used to classify 11 subjects as cases, and 15 without WMH as controls. Plasma total exosomes were precipitated and EDEs enriched by sequential immuno-precipitations. In addition, we quantified three inflammatory cytokines from plasma and imaging variables on MRI. Group means were compared, the discriminant functions of biomarkers calculated, and the association of EDE biomarkers with plasma inflammatory markers, cognition, and imaging outcomes assessed via regression modeling.

Results: Plasma levels of EDE cargo proteins GLUT1, LAT1, P-GP, and NOSTRIN were significantly higher in subjects with WMH in comparison to those without. In contrast, EDE levels of the marker with low expression in brain (VCAM1) were equal between groups. The effect sizes for each of the brain-expressed cargo proteins (GLUT1, LAT1, and P-GP) were such that age-adjusted logistic regressions revealed areas under the curve (AUC) with range of 0.82–0.89, differentiating subjects with WMH from those without. VCAM1 poorly discriminated between groups (AUC:0.55). Higher levels of all brain-expressed EDE proteins were also associated with lower cognitive function, unrelated to burden of WMH. Levels of LAT1 and P-GP were significantly inversely associated with global gray matter volumes, and EDE GLUT1, LAT-1, and P-GP concentrations were significantly associated with systemic IL-6 levels.

Conclusion: In a case control study of clinically normal adults with and without WMH, concentrations of EDE proteins were significantly higher in subjects with WMH in comparison to controls. This work is a first step toward in vivo dissection of molecular changes in endothelia of functionally normal subjects with radiographic evidence of age-associated white matter disease.

Transcutaneous electrical acupoint stimulation for prevention of postoperative delirium in geriatric patients with silent lacunar infarction: a preliminary study

Purpose

This study aims to investigate the effect of transcutaneous electrical acupoint stimulation (TEAS) on postoperative delirium (POD) in elderly patients with silent lacunar infarct and preliminarily to determine the relationship among TEAS, blood–brain barrier (BBB), neuroinflammation, and POD.

Patients and methods

Sixty-four-old patients with silent lacunar infarct were randomly divided into two groups: group TEAS and control group (group C). Patients in the group TEAS received TEAS (disperse-dense waves; frequency, 2/100 Hz) on acupoints Hegu and Neiguan of both sides starting from 30 minutes before induction of anesthesia until the end of surgery, and the intensity was the maximum current that could be tolerated. In group C, electrodes were placed on the same acupoints before anesthesia induction, but no current was given. At 0 minute before the treatment of TEAS, 30 minutes after skin incision, and after completion of surgery (T_1–3), blood samples were extracted to detect the concentration of serum tumor necrosis factor (TNF)-α, interleukin-6 (IL-6), matrix metalloproteinase-9 (MMP-9), and S100β. We assessed patients for delirium and coma twice daily in the first 3 postoperative days using the Confusion Assessment Method for the intensive care unit and the Richmond Agitation-Sedation Scale.

Results

This study preliminarily suggests that TEAS can reduce the development of POD in elderly patients with silent lacunar infarction (6.3% vs 25.0%; P=0.039). Compared with the baseline value at T₁, the serum concentrations of IL-6, TNF-α, MMP-9, and S100β were significantly increased at T_2–3 in both the groups (P<0.05). Compared with group TEAS, serum levels of TNF-α and IL-6 were higher at T_2–3 and serum levels of MMP-9 and S100β were higher at T₃ in group C (P<0.05). The intraoperative anesthetic consumptions were less in group TEAS than group C.

Conclusion

TEAS can alleviate POD in older patients with silent lacunar infarction and may be related to reduce the neuroinflammation by lowering the permeability of BBB.

Isolation of Rodent Brain Vessels

The prevalence of neurodegenerative diseases is increasing worldwide. Cerebrovascular disorders and/or conditions known to affect brain vasculature, such as diabetes, are well-known risk factors for neurodegenerative diseases. Thus, the evaluation of the brain vasculature is of great importance to better understand the mechanisms underlying brain damage. We established a protocol for the isolation of brain vessels from rodents. This is a simple, non-enzymatic isolation protocol that allows us to perform comparative studies in different animal models of disease, helping understand the impact of several pathological conditions on brain vasculature and how those alterations predispose to neurodegenerative conditions.

Impact of multiple pathologies on the threshold for clinically overt dementia

Longitudinal clinical-pathological studies have increasingly recognized the importance of mixed pathologies (the coexistence of one or more neurodegenerative and cerebrovascular disease pathologies) as important factors in the development of Alzheimer's disease (AD) and other forms of dementia. Older persons with AD pathology, often have concomitant cerebrovascular disease pathologies (macroinfarcts, microinfarcts, atherosclerosis, arteriolosclerosis, cerebral amyloid angiopathy) as well as other concomitant neurodegenerative disease pathologies (Lewy bodies, TDP-43, hippocampal sclerosis). These additional pathologies lower the threshold for clinical diagnosis of AD. Many of these findings from pathologic studies, especially for CVD, have been confirmed using sophisticated neuroimaging technologies. In vivo biomarker studies are necessary to provide an understanding of specific pathologic contributions and time course relationships along the spectrum of accumulating pathologies. In this review, we provide a clinical-pathological perspective on the role of multiple brain pathologies in dementia followed by a review of the available clinical and biomarker data on some of the mixed pathologies.

Texture analysis of the developing human brain using customization of a knowledge-based system

Background: Pattern recognition software originally designed for geospatial and other technical applications could be trained by physicians and used as texture-analysis tools for evidence-based practice, in order to improve diagnostic imaging examination during pregnancy.Methods: Various machine-learning techniques and customized datasets were assessed for training of an integrable knowledge-based system (KBS), to determine a hypothetical methodology for texture classification of closely-related anatomical structures in fetal brain magnetic resonance (MR) images. Samples were manually categorized according to the magnetic field of the MRI scanner (i.e. 1.5-tesla (1.5T), 3-tesla (3T)), rotational planes (i.e. coronal, sagittal and axial), and signal weighting (i.e. spin-lattice, spin-spin, relaxation, proton density). In the machine-learning sessions, the operator manually selected relevant regions of interest (ROI) in 1.5/3T MR images. Semi-automatic procedures in MaZda/B11 were performed to determine optimal parameter sets for ROI classification. Four classes were defined: ventricles, thalamus, grey matter, and white matter. Various textures analysis methods were tested. The KBS performed automatic data pre-processing and semi-automatic classification of ROIs.Results: After testing 3456 ROIs, statistical binary classification revealed that combination of reduction techniques with linear discriminant algorithms (LDA) or nonlinear discriminant algorithms (NDA) yielded the best scoring in terms of sensitivity (both 100%, 95% CI: 99.79-100), specificity (both 100%, 95% CI: 99.79-100) and Fisher coefficient (≈E+4, ≈E+5, respectively). Conclusions: LDA and NDA in MaZda can be useful data mining tools for screening a population of interest subjected to a clinical test.

Aortic Stiffness, Cerebrovascular Dysfunction, and Memory

BACKGROUND

Aortic stiffness is associated with cardiovascular and cerebrovascular events and cognitive decline. This mini-review focuses on relations of aortic stiffness with microvascular dysfunction and discusses the contribution of abnormal pulsatile hemodynamics to cerebrovascular damage and cognitive decline. We also provide a rationale for considering aortic stiffness as a putative and important contributor to memory impairment in older individuals.

SUMMARY

Aging is associated with stiffening of the aorta but not the muscular arteries, which reduces wave reflection and increases the transmission of pulsatility into the periphery. Aortic stiffening thereby impairs a protective mechanism that shields the peripheral microcirculation from excessive pulsatility within downstream target organs. Beyond midlife, aortic stiffness increases rapidly and exposes the cerebral microcirculation to abnormal pulsatile mechanical forces that are associated with microvascular damage and remodeling in the brain. Aortic stiffening and high-flow pulsatility are associated with alterations in the microvasculature of the brain; however, a mechanistic link between aortic stiffness and memory has not been established. We showed that in a community-based sample of older individuals, cerebrovascular resistance and white matter hyperintensities - markers of cerebrovascular remodeling and damage - mediated the relation between higher aortic stiffness and lower performance on memory function tests. These data suggest that microvascular and white matter damage associated with excessive aortic stiffness contribute to impaired memory function with advancing age.

KEY MESSAGES

Increasing evidence suggests that vascular etiologies - including aortic stiffness and microvascular damage - contribute to memory impairment and the pathogenesis of dementia, including Alzheimer's disease. Interventions that reduce aortic stiffness may delay memory decline among older individuals.

Magnetic resonance imaging in Alzheimer's Disease Neuroimaging Initiative 2

INTRODUCTION

Alzheimer's Disease Neuroimaging Initiative (ADNI) is now in its 10th year. The primary objective of the magnetic resonance imaging (MRI) core of ADNI has been to improve methods for clinical trials in Alzheimer's disease (AD) and related disorders.

METHODS

We review the contributions of the MRI core from present and past cycles of ADNI (ADNI-1, -Grand Opportunity and -2). We also review plans for the future-ADNI-3.

RESULTS

Contributions of the MRI core include creating standardized acquisition protocols and quality control methods; examining the effect of technical features of image acquisition and analysis on outcome metrics; deriving sample size estimates for future trials based on those outcomes; and piloting the potential utility of MR perfusion, diffusion, and functional connectivity measures in multicenter clinical trials.

DISCUSSION

Over the past decade the MRI core of ADNI has fulfilled its mandate of improving methods for clinical trials in AD and will continue to do so in the future.

Molecular disorganization of axons adjacent to human lacunar infarcts

Cerebral microvascular disease predominantly affects brain white matter and deep grey matter, resulting in ischaemic damage that ranges from lacunar infarcts to white matter hyperintensities seen on magnetic resonance imaging. These lesions are common and result in both clinical stroke syndromes and accumulate over time, resulting in cognitive deficits and dementia. Magnetic resonance imaging studies suggest that these lesions progress over time, accumulate adjacent to prior lesions and have a penumbral region susceptible to further injury. The pathological correlates of this adjacent injury in surviving myelinated axons have not been previously defined. In this study, we sought to determine the molecular organization of axons in tissue adjacent to lacunar infarcts and in the regions surrounding microinfarcts, by determining critical elements in axonal function: the morphology and length of node of Ranvier segments and adjacent paranodal segments. We examined post-mortem brain tissue from six patients with lacunar infarcts and tissue from two patients with autosomal dominant retinal vasculopathy and cerebral leukoencephalopathy (previously known as hereditary endotheliopathy with retinopathy, nephropathy and stroke) who accumulate progressive white matter ischaemic lesions in the form of lacunar and microinfarcts. In axons adjacent to lacunar infarcts yet extending up to 150% of the infarct diameter away, both nodal and paranodal length increase by ∼20% and 80%, respectively, reflecting a loss of normal cell-cell adhesion and signalling between axons and oligodendrocytes. Using premorbid magnetic resonance images, brain regions from patients with retinal vasculopathy and cerebral leukoencephalopathy that harboured periventricular white matter hyperintensities were selected and the molecular organization of axons was determined within these regions. As in regions adjacent to lacunar infarcts, nodal and paranodal length in white matter of these patients is increased. Myelin basic protein and neurofilament immunolabelling demonstrates that axons in these adjacent regions have preserved axonal cytoskeleton organization and are generally myelinated. This indicates that the loss of normal axonal microdomain architecture results from disrupted axoglial signalling in white matter adjacent to lacunar and microinfarcts. The loss of the normal molecular organization of nodes and paranodes is associated with axonal degeneration and may lead to impaired conduction velocity across surviving axons after stroke. These findings demonstrate that the degree of white matter injury associated with cerebral microvascular disease extends well beyond what can be identified using imaging techniques and that an improved understanding of the neurobiology in these regions can drive new therapeutic strategies for this disease entity.

Hippocampal cAMP/PKA/CREB is required for neuroprotective effect of acupuncture

Acupuncture has beneficial effects in vascular dementia (VaD) patients. The underlying mechanism, however, remains unknown. The present study was designed to investigate whether the cAMP/PKA/CREB cascade is involved in the mechanism of acupuncture in cerebral multi-infarction rats. In this study, cerebral multi-infarction was modeled in adult Wistar rats by homologous blood clot emboli. After a two-week acupuncture treatment at Zusanli (ST36), hippocampal-dependent memory was tested by employing a radial arm maze test. The hippocampus was isolated for analyses of cAMP concentration, phosphodiesterase (PDE) activity and CREB/pCREB and ERK/pERK expressions. The Morris water maze (MWM) task and CREB phosphorylation were evaluated in the presence of PKA-selective peptide inhibitor (H89). The radial arm maze test results demonstrated that acupuncture treatment at ST36 reversed hippocampal-dependent memory in impaired animals. Compared to those of the impaired group, cAMP concentration, PKA activity and pCREB and pERK expressions were increased following acupuncture therapy. Finally, the blockade of PKA reversed the increase in CREB phosphorylation and the improvement in recognitive function induced by acupuncture treatment. These results suggest that acupuncture could improve hippocampus function by modulating the cAMP/PKA/CREB signaling pathway, which represents a molecular mechanism of acupuncture for recognitive function in cerebral multi-infarction rats.

Ratio of urine albumin to creatinine attenuates the association of dementia with hip fracture risk

CONTEXT

Microvascular disease is a leading cause of cognitive impairment. Approximately 50% of people with a hip fracture have cognitive impairment.

OBJECTIVE

We tested the hypothesis that microvascular diseases of the brain (lacunar infarcts and white matter disease [WMD]), kidney (albuminuria [≥ 30 mg/g creatinine] and albumin creatinine ratio [ACR]), and eye (retinal vascular disorders) attenuate the association of cognitive impairment with hip fracture risk.

SETTING

The Cardiovascular Health Cognition Study.

PATIENTS

Three thousand, one-hundred six participants (mean age, ∼ 79 y; 8.84 y median follow-up) with cognitive testing. Subsets received ACR testing (n=2389), brain magnetic resonance imaging scans (n = 2094), and retinal photography (n = 1098).

MAIN OUTCOME MEASURE

Incident hip fracture.

RESULTS

There were 488 participants (16%) with mild cognitive impairment (MCI) and 564 (18%) with dementia. There were 337 incident hip fractures, of which 19% occurred in participants with MCI and 26% in participants with dementia. Adjusted hazard ratios (HR) and 95% confidence interval for hip fracture in participants with MCI were 2.45 (1.67-3.61) and for dementia 2.35 (1.57-3.52). With doubling of ACR, the HR for fracture was attenuated in participants with dementia compared with participants with normal cognition [interaction HR 0.70 (0.55-0.91)]. No such effect was found in participants with MCI. Albuminuria, lacunar infarcts, WMD, and retinal vascular disease (RVD) did not modify the association of dementia or MCI with hip fracture risk.

CONCLUSIONS

ACR attenuates part of the risk of hip fracture in people with dementia, suggesting that these disorders share a common pathogenesis.

Structural imaging measures of brain aging

During the course of normal aging, biological changes occur in the brain that are associated with changes in cognitive ability. This review presents data from neuroimaging studies of primarily "normal" or healthy brain aging. As such, we focus on research in unimpaired or nondemented older adults, but also include findings from lifespan studies that include younger and middle aged individuals as well as from populations with prodromal or clinically symptomatic disease such as cerebrovascular or Alzheimer's disease. This review predominantly addresses structural MRI biomarkers, such as volumetric or thickness measures from anatomical images, and measures of white matter injury and integrity respectively from FLAIR or DTI, and includes complementary data from PET and cognitive or clinical testing as appropriate. The findings reveal highly consistent age-related differences in brain structure, particularly frontal lobe and medial temporal regions that are also accompanied by age-related differences in frontal and medial temporal lobe mediated cognitive abilities. Newer findings also suggest that degeneration of specific white matter tracts such as those passing through the genu and splenium of the corpus callosum may also be related to age-related differences in cognitive performance. Interpretation of these findings, however, must be tempered by the fact that comorbid diseases such as cerebrovascular and Alzheimer's disease also increase in prevalence with advancing age. As such, this review discusses challenges related to interpretation of current theories of cognitive aging in light of the common occurrence of these later-life diseases. Understanding the differences between "Normal" and "Healthy" brain aging and identifying potential modifiable risk factors for brain aging is critical to inform potential treatments to stall or reverse the effects of brain aging and possibly extend cognitive health for our aging society.

Aggregate effects of vascular risk factors on cerebrovascular changes in autopsy-confirmed Alzheimer's disease

We examined the relationships of antemortem vascular risk factors to postmortem cerebrovascular and Alzheimer's disease (AD) pathologies. Eighty-four AD patients underwent an assessment of vascular risk (blood pressure, cholesterol, smoking, cardiovascular disease, diabetes, atrial fibrillation, transient ischemic attack [TIA], or stroke) and later underwent brain autopsy. Given our aim to examine mild cerebrovascular changes (CVCs), individuals were excluded if autopsy revealed large stroke. The most common forms of CVC were circle of Willis atherosclerosis followed by arteriosclerosis, lacunes, and microinfarcts. Excluding the history of TIA/clinical stroke, individual vascular risk factors were not associated with CVC. However, the presence of multiple vascular risk factors was associated with CVC. Furthermore, the presence of CVC was associated with lower Braak and Braak stage. These findings highlight the importance of aggregate risk in the vascular contribution to dementia. Interventions designed to maintain cerebrovascular health may represent important opportunities for preventing or delaying dementia, even when AD is the dominant pathology.

Dysthymic disorder in the elderly population

The diagnosis of dysthymic disorder was created in DSM-III and maintained in DSM-IV to describe a depressive syndrome of mild to moderate severity of at least two years' duration that did not meet criteria for major depressive disorder. The prevalence of dysthymic disorder is approximately 2% in the elderly population where subsyndromal depressions of lesser severity are more common. Dysthymic disorder was replaced in DSM-V by the diagnosis of "persistent depressive disorder" that includes chronic major depression and dysthymic disorder. In older adults, epidemiological and clinical evidence supports the use of the term "dysthymic disorder." In contrast to young adults with dysthymic disorder, older adults with dysthymic disorder commonly present with late age of onset, without major depression and other psychiatric disorders, and with a low rate of family history of mood disorders. They often have stressors such as loss of social support and bereavement, and some have cerebrovascular or neurodegenerative pathology. A minority has chronic depression dating from youth with psychiatric comorbidity similar to young adults with dysthymic disorder. In older adults, both dysthymic disorder and subsyndromal depression increase disability and lead to poor medical outcomes. Elderly patients with dysthymic disorder are seen mainly in primary care where identification and treatment are often inadequate. Treatment with antidepressant medication shows marginal superiority over placebo in controlled trials, and problem-solving therapy shows similar efficacy. Combined treatment and collaborative care models show slightly better results, but cost effectiveness is a concern. Further work is needed to clarify optimal approaches to the treatment of dysthymic disorder in elderly patients.

Cardiovascular disease and cognitive decline in postmenopausal women: results from the Women's Health Initiative Memory Study

BACKGROUND

Data on cardiovascular diseases (CVD) and cognitive decline are conflicting. Our objective was to investigate if CVD is associated with an increased risk for cognitive decline and to examine whether hypertension, diabetes, or adiposity modify the effect of CVD on cognitive functioning.

METHODS AND RESULTS

Prospective follow-up of 6455 cognitively intact, postmenopausal women aged 65 to 79 years old enrolled in the Women's Health Initiative Memory Study (WHIMS). CVD was determined by self-report. For cognitive decline, we assessed the incidence of mild cognitive impairment (MCI) or probable dementia (PD) via modified mini-mental state examination (3 MS) score, neurocognitive, and neuropsychiatric examinations. The median follow-up was 8.4 years. Women with CVD tended to be at increased risk for cognitive decline compared with those free of CVD (hazard ratio [HR], 1.29; 95% CI: 1.00, 1.67). Women with myocardial infarction or other vascular disease were at highest risk (HR, 2.10; 95% CI: 1.40, 3.15 or HR, 1.97; 95% CI: 1.34, 2.87). Angina pectoris was moderately associated with cognitive decline (HR 1.45; 95% CI: 1.05, 2.01) whereas no significant relationships were found for atrial fibrillation or heart failure. Hypertension and diabetes increased the risk for cognitive decline in women without CVD. Diabetes tended to elevate the risk for MCI/PD in women with CVD. No significant trend was seen for adiposity.

CONCLUSIONS

CVD is associated with cognitive decline in elderly postmenopausal women. Hypertension and diabetes, but not adiposity, are associated with a higher risk for cognitive decline. More research is warranted on the potential of CVD prevention for preserving cognitive functioning.

The Women's Healthy Ageing Project: fertile ground for investigation of healthy participants 'at risk' for dementia

Alzheimer's disease neuropathology (amyloid, tauopathies) and brain atrophy are present decades prior to manifestation of clinical symptoms. With the failure of treatment trials it is becoming clearer that the window for prevention and therapeutic intervention is before significant neuronal loss and clinical deterioration of cognition has occurred. Early identification of those at risk of disease and optimizing their management to prevent disease in later life are crucial to delaying disease onset and improving people's quality of life. The Women's Healthy Aging Project (WHAP) is a longitudinal study of over 400 Australian-born women, epidemiologically randomly sampled in 1990. The WHAP aims to identify modifiable mid-life risk factors for the development of late-life cognitive decline, improve the understanding of the pathogenesis of dementia, and target early disease identification utilizing clinical, biomarker and health risk profiles. These aims are fortified by the ability to leverage the considerable database on health, lifestyle and socio-demographics collected prospectively from 1990 to date. This is the first study with a comprehensive neuropsychological battery, over a decade of cognitive follow-up, with all participants being offered amyloid imaging from 2012, and prospective longitudinal data including clinical and physical measures and bio-bank samples from over 20 years prior.

Transient focal cerebral ischemia induces long-term cognitive function deficit in an experimental ischemic stroke model

Vascular dementia ranks as the second leading cause of dementia in the United States. However, its underlying pathophysiological mechanism is not fully understood and no effective treatment is available. The purpose of the current study was to evaluate long-term cognitive deficits induced by transient middle cerebral artery occlusion (tMCAO) in rats and to investigate the underlying mechanism. Sprague-Dawley rats were subjected to tMCAO or sham surgery. Behavior tests for locomotor activity and cognitive function were conducted at 7 or 30days after stroke. Hippocampal long term potentiation (LTP) and involvement of GABAergic neurotransmission were evaluated at 30days after sham surgery or stroke. Immunohistochemistry and Western blot analyses were conducted to determine the effect of tMCAO on cell signaling in the hippocampus. Transient MCAO induced a progressive deficiency in spatial performance. At 30days after stroke, no neuron loss or synaptic marker change in the hippocampus were observed. LTP in both hippocampi was reduced at 30days after stroke. This LTP impairment was prevented by blocking GABAA receptors. In addition, ERK activity was significantly reduced in both hippocampi. In summary, we identified a progressive decline in spatial learning and memory after ischemic stroke that correlates with suppression of hippocampal LTP, elevation of GABAergic neurotransmission, and inhibition of ERK activation. Our results indicate that the attenuation of GABAergic activity or enhancement of ERK/MAPK activation in the hippocampus might be potential therapeutic approaches to prevent or attenuate cognitive impairment after ischemic stroke.