Blood Pressure Variability and Progression of Clinical Alzheimer Disease

Hypotension with neurovascular changes and cognitive dysfunction: An epidemiological, pathobiological, and treatment review

ABSTRACT

Hypotension is a leading cause of age-related cognitive impairment. The available literature evidences that vascular factors are associated with dementia and that hypotension alters cerebral perfusion flow and can aggravate the neurodegeneration of Alzheimer's disease (AD). Despite the discovery of biomarkers and the recent progress made in neurovascular biology, epidemiology, and brain imaging, some key issues remain largely unresolved: the potential mechanisms underlying the neural deterioration observed in AD, the effect of cerebrovascular alterations on cognitive deficits, and the positive effects of hypotension treatment on cognition. Therefore, further well-designed studies are needed to unravel the potential association between hypotension and cognitive dysfunction and reveal the potential benefits of hypotension treatment for AD patients. Here, we review the current epidemiological, pathobiological, and treatment-related literature on neurovascular changes and hypotension-related cognitive dysfunction and highlight the unsettled but imminent issues that warrant future research endeavors.

Visit-to-visit variability in multiple biological measurements and cognitive performance and risk of cardiovascular disease: A cohort study

Background

Visit-to-visit variability in single biological measurements has been associated with cognitive decline and an elevated risk of cardiovascular diseases (CVD). However, the effect of visit-to-visit variability in multiple biological measures is underexplored. We investigated the effect of visit-to-visit variability in blood pressure (BP), heart rate (HR), weight, fasting plasma glucose, cholesterol, and triglycerides on cognitive performance and CVD.

Methods

Data on BP, HR, weight, glucose, cholesterol, and triglycerides from study visits in the Outcome Reduction with Initial Glargine Intervention (ORIGIN) trial were used to estimate the association between visit-to-visit variability, cognitive performance (Mini Mental State Examination (MMSE) score) and CVD (non-fatal stroke, non-fatal myocardial infarction, or cardiovascular death). Visit-to-visit variation for each measurement was estimated by calculating each individuals visit-to-visit standard deviation for that measurement. Participants whose standard deviation was in the highest quarter were classified as having high variation. Participants were grouped into those having 0, 1, 2, 3, or ≥ 4 high variation measurements. Regression and survival models were used to estimate the association between biological measures with MMSE and CVD with adjustment for confounders and mean measurement value.

Results

After adjustment for covariates, higher visit-to-visit variability in BP, HR, weight, and FPG were associated with poorer MMSE and a higher risk of CVD. Effect sizes did not vary greatly by measurement. The effects of high visit-to-visit variability were additive; compared to participants who had no measurements with high visit-to-visit variability, those who had high visit-to-visit variability in ≥4 measurements had poorer MMSE scores (-0.63 (95 % CI -0.96 to -0·31). Participants with ≥4 measurements with high visit-to-visit variability compared to participants with none had higher risk of CVD (hazard ratio 2.46 (95 % CI 1.63 to 3.70).

Conclusion

Visit-to-visit variability in several measurements were associated with cumulatively poorer cognitive performance and a greater risk of CVD.

Temporal and region-specific tau hyperphosphorylation in the medulla and forebrain coincides with development of functional changes in male obese Zucker rats

Metabolic syndrome (MetS) is associated with development of tauopathies that contribute to cognitive decline. Without functional leptin receptors, male obese Zucker rats (OZRs) develop MetS, and they have increased phosphorylated tau (ptau) with impaired cognitive function. In addition to regulating energy balance, leptin enhances activation of the hippocampus, which is essential for spatial learning and memory. Whether spatial learning and memory are always impaired in OZRs or develop with MetS is unknown. We hypothesized that male OZRs develop MetS traits that promote regional increases in ptau and functional deficits associated with those brain regions. In the medulla and cortex, tau-pSer199,202 and tau-pSer396 were comparable in juvenile (7-8 wk old) lean Zucker rats (LZRs) and OZRs but increased in 18- to 19-wk-old OZRs. Elevated tau-pSer396 was concentrated in the dorsal vagal complex of the medulla, and by this age OZRs had hypertension with increased arterial pressure variability. In the hippocampus, tau-pSer199,202 and tau-pSer396 were still comparable in 18- to 19-wk-old OZRs and LZRs but elevated in 28- to 29-wk-old OZRs, with emergence of deficits in Morris water maze performance. Comparable escape latencies observed during acquisition in 18- to 19-wk-old OZRs and LZRs were increased in 28- to 29-wk-old OZRs, with greater use of nonspatial search strategies. Increased ptau developed with changes in the insulin/phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway in the hippocampus and cortex but not medulla, suggesting different underlying mechanisms. These data demonstrate that leptin is not required for spatial learning and memory in male OZRs. Furthermore, early development of MetS-associated autonomic dysfunction by the medulla may be predictive of later hippocampal dysfunction and cognitive impairment.NEW & NOTEWORTHY Male obese Zucker rats (OZRs) lack functional leptin receptors and develop metabolic syndrome (MetS). At 16-19 wk, OZRs are insulin resistant, with increased ptau in dorsal medulla and impaired autonomic regulation of AP. At 28-29 wk OZRs develop increased ptau in hippocampus with deficits in spatial learning and memory. Juvenile OZRs lack elevated ptau and these deficits, demonstrating that leptin is not essential for normal function. Elevated ptau and deficits emerge before the onset of diabetes in insulin-resistant OZRs.

Short-term blood pressure variability and brain functional network connectivity in older adults

Background

Blood pressure variability is increasingly linked with cerebrovascular disease and Alzheimer's disease, independent of mean blood pressure levels. Elevated blood pressure variability is also associated with attenuated cerebrovascular reactivity, which may have implications for functional hyperemia underpinning brain network connectivity. It remains unclear whether blood pressure variability is related to functional network connectivity. We examined relationships between beat-to-beat blood pressure variability and functional connectivity in brain networks vulnerable to aging and Alzheimer's disease.

Methods

53 community-dwelling older adults (mean [SD] age = 69.9 [7.5] years, 62.3% female) without history of dementia or clinical stroke underwent continuous blood pressure monitoring and resting state fMRI scan. Blood pressure variability was calculated as variability independent of mean. Functional connectivity was determined by resting state fMRI for several brain networks: default, salience, dorsal attention, fronto-parietal, and language. Multiple linear regression examined relationships between short-term blood pressure variability and functional network connectivity.

Results

Elevated short-term blood pressure variability was associated with lower functional connectivity in the default network (systolic: standardized ß = -0.30 [95% CI -0.59, -0.01], p = .04). There were no significant associations between blood pressure variability and connectivity in other functional networks or between mean blood pressure and functional connectivity in any network.

Discussion

Older adults with elevated short-term blood pressure variability exhibit lower resting state functional connectivity in the default network. Findings support the role of blood pressure variability in neurovascular dysfunction and Alzheimer's disease. Blood pressure variability may represent an understudied early vascular risk factor for neurovascular dysfunction relevant to Alzheimer's disease, with potential therapeutic implications.

Blood pressure variability supersedes heart rate variability as a real-world measure of dementia risk

Blood pressure variability (BPV) and heart rate variability (HRV) have been associated with Alzheimer's Disease and Related Dementias (ADRD) in rigorously controlled studies. However, the extent to which BPV and HRV may offer predictive information in real-world, routine clinical care is unclear. In a retrospective cohort study of 48,204 adults (age 54.9 ± 17.5 years, 60% female) receiving continuous care at a single center, we derived BPV and HRV from routinely collected clinical data. We use multivariable Cox models to evaluate the association of BPV and HRV, separately and in combination, with incident ADRD. Over a median 3 [2.4, 3.0] years, there were 443 cases of new-onset ADRD. We found that clinically derived measures of BPV, but not HRV, were consistently associated with incident ADRD. In combined analyses, only patients in both the highest quartile of BPV and lowest quartile of HRV had increased ADRD risk (HR 2.34, 95% CI 1.44-3.81). These results indicate that clinically derived BPV, rather than HRV, offers a consistent and readily available metric for ADRD risk assessment in a real-world patient care setting. Thus, implementation of BPV as a widely accessible tool could allow clinical providers to efficiently identify patients most likely to benefit from comprehensive ADRD screening.

Visit-to-visit variability in blood pressure and the risk of open-angle glaucoma in individuals without systemic hypertension: a nationwide population-based cohort study

Purpose

We aimed to evaluate the effect of visit-to-visit variability in blood pressure (BP) on the risk of open-angle glaucoma (OAG) in individuals without systemic hypertension using a population-based retrospective cohort study design.

Methods

The Korean National Health Insurance Service-National Health Screening Cohort database, which collected data of 209,226 individuals between 2002 and 2015, was used to analyze the data of 140,910 eligible participants. The mean follow-up duration was 8.3 years. Visit-to-visit BP variability was assessed using standard deviation (SD), coefficient of variation (CV), and variability independent of the mean (VIM). Participants were categorized into four groups according to BP variability quartiles. We verified the effect of BP variability by comparing participants of the first to third quartiles of BP variability groups with those belonging to the fourth quartile group. A Cox proportional hazards model was used to determine the hazard ratio (HR) of BP variability in cases of newly diagnosed OAG. Moreover, we conducted subgroup analyses using baseline characteristics.

Results

In the multivariable analyses, BP variability did not significantly increase the risk of OAG development. However, subgroup analyses revealed significant interactions between age and systolic BP variability in the development of OAG (CV: p = 0.008; SD: p = 0.007). For participants aged <60 years, the risk of OAG development significantly increased with high systolic BP variability (CV: HR, 1.18; 95% confidence interval [CI], 1.00-1.39; p = 0.049). We observed a similar trend using the SD and VIM as the parameters for systolic BP variability.

Conclusion

Higher visit-to-visit systolic BP variability was associated with an increased risk of OAG development in participants younger than 60 years of age without systemic hypertension. These results suggest that BP variability can be the considerable factor when assessing the risk of OAG, especially in relatively young people without systemic hypertension.

Blood Pressure Variability and Plasma Alzheimer's Disease Biomarkers in the SPRINT Trial

Background

Recent observational studies suggest higher blood pressure (BP) variability (BPV) is associated with Alzheimer's disease (AD) biomarkers amyloid-beta (Aβ) and tau. Less is known about relationships in interventional cohorts with strictly controlled mean BP levels.

Objective

Investigate the longitudinal relationship between BPV and change in plasma AD biomarkers under standard versus intensive BP treatment.

Methods

In this post hoc analysis of the SPRINT trial, 457 participants (n = 206 in standard group, n = 251 in intensive group) underwent repeated BP measurement between baseline and 12-months follow-up, and venipuncture at baseline and median (IQR) 3.5 (3.0-4.0) years later to determine plasma AD biomarkers total tau and Aβ1-42:Aβ1-40 ratio. BPV was calculated as tertiles of variability independent of mean. Linear mixed models investigated the effect of BPV×time on AD biomarker levels.

Results

Higher BPV was associated with increased levels of total tau in the standard group (β [95% CI] 1st versus 3rd tertiles of BPV: 0.21 [0.02, 0.41], p = 0.035), but not in the intensive group (β [95% CI] 1st versus 3rd tertiles of BPV: -0.02 [-0.19, 0.16], p = 0.843). BPV was not associated with Aβ 1-42:Aβ 1-40 ratio in either group. Mean BP was not associated with biomarkers.

Conclusions

Higher BPV was associated with increased plasma total tau under standard BP treatment. Findings add new evidence to prior observational work linking BPV to AD pathophysiology and suggest that, despite strict control of mean BP, BPV remains a risk for pathophysiological change underlying risk for AD.

Association between the blood pressure variability and cognitive decline in Parkinson's disease

OBJECTIVES

High visit-to-visit blood pressure variability (BPV) was found to be associated with cognitive decline in the elderly. This study aimed to investigate the impact of visit-to-visit BPV on cognition in patients with early-stage Parkinson's disease (PD).

DESIGN

This is a retrospective analysis of a prospective cohort.

SETTING AND PARTICIPANTS

A total of 297 patients with early-stage PD (103 mild cognitive impairments [PD-MCI] and 194 normal cognitions [PD-NC] at baseline) were included from the Parkinson's Progression Markers Initiative study.

METHODS

Variation independent of mean (VIM) of the first year was used as the indicator of BPV. The Montreal Cognitive Assessment (MoCA) was used to assess global cognition. Patients were divided into PD-MCI and PD-NC according to the MoCA score at baseline. Longitudinal cerebrospinal fluid (Aβ-42, Aβ, α-synuclein, neurofilament light protein, tau phosphorylated at the threonine 181 position, total tau, glial fibrillary acidic protein) and serum (neurofilament light protein) biomarkers were assessed. The Bayesian linear growth model was used to evaluate the relationship between baseline BPV and the rate of change in cognition and biomarkers.

RESULTS

Higher systolic VIM of the first year was related to a greater rate of decline in MoCA score in the following years in PD-MCI (β = -.15 [95% CI -.29, -.01]). No association was found between BPV and biomarkers.

CONCLUSION AND IMPLICATIONS

Higher systolic VIM predicted a steeper decline in cognitive tests in PD-MCI independently from the mean value of blood pressure, orthostatic hypotension, and supine hypertension.

Analysis of the relationship between blood pressure variability and subtle cognitive decline in older adults

BACKGROUND

Blood pressure variability (BPV) has been shown to be related to mild cognitive impairment and Alzheimer's disease in a number of studies. However, the relationship between BPV and subtle cognitive decline (SCD) has received minimal attention in this field of research to date and has rarely been reported.

AIM

To examine whether SCD is independently associated with changes in BPV in older adults.

METHODS

Participants were selected based on having participated in cognitive function evaluation and ambulatory blood pressure measurement at the Shanghai Sixth People's Hospital Affiliated with Shanghai Jiao Tong University School of Medicine between June 2020 and August 2022. The participants included 182 individuals with SCD as the experimental group and 237 with normal cognitive function as the control group. The basic data, laboratory examinations, scale tests, and ambulatory blood pressure test results of the two groups were analyzed retrospectively, and the relationship between SCD and BPV was subsequently evaluated.

RESULTS

Significant differences were observed between the two groups of participants (P < 0.05) in terms of age, education level, prevalence rate of diabetes, fasting blood glucose level, 24-h systolic blood pressure standard deviation and coefficient of variation, 24-h diastolic blood pressure standard deviation and coefficient of variation. The scale monitoring results showed significant differences in the scores for memory, attention, and visual space between the experimental and control groups. Logistic regression analysis indicated that age, education level, blood sugar level, and BPV were factors influencing cognitive decline. Linear regression analysis showed that there was an independent correlation between blood pressure variation and SCD, even after adjusting for related factors. Each of the above differences was still significant.

CONCLUSION

This study suggests that increased BPV is associated with SCD.

Long-term blood pressure patterns in midlife and dementia in later life: Findings from the Framingham Heart Study

INTRODUCTION

Long-term blood pressure (BP) measures, such as visit-to-visit BP variability (BPV) and cumulative BP, are strong indicators of cardiovascular risks. This study modeled up to 20 years of BP patterns representative of midlife by using BPV and cumulative BP, then examined their associations with development of dementia in later life.

METHODS

For 3201 individuals from the Framingham Heart Study, multivariate logistic regression analyses were performed to examine the association between long-term BP patterns during midlife and the development of dementia (ages ≥ 65).

RESULTS

After adjusting for covariates, every quartile increase in midlife cumulative BP was associated with a sequential increase in the risk of developing dementia (e.g., highest quartile of cumulative systolic blood pressure had approximately 2.5-fold increased risk of all-cause dementia). BPV was not significantly associated with dementia.

DISCUSSION

Findings suggest that cumulative BP over the course of midlife predicts risk of dementia in later life. HIGHLIGHTS Long-term blood pressure (BP) patterns are strong indicators of vascular risks. Cumulative BP and BP variability (BPV) were used to reflect BP patterns across midlife. High cumulative BP in midlife is associated with increased dementia risk. Visit-to-visit BPV was not associated with the onset of dementia.

Short-term blood pressure variability is inversely related to regional amplitude of low frequency fluctuations in older and younger adults

Blood pressure variability (BPV), independent of mean blood pressure levels, is associated with cerebrovascular disease burden on MRI and postmortem evaluation. However, less is known about relationships with markers of cerebrovascular dysfunction, such as diminished spontaneous brain activity as measured by the amplitude of low frequency fluctuations (ALFF), especially in brain regions with vascular and neuronal vulnerability in aging. We investigated the relationship between short-term BPV and concurrent regional ALFF from resting state fMRI in a sample of community-dwelling older adults (n = 44) and healthy younger adults (n = 49). In older adults, elevated systolic BPV was associated with lower ALFF in widespread medial temporal regions and the anterior cingulate cortex. Higher systolic BPV in younger adults was also related to lower ALFF in the medial temporal lobe, albeit in fewer subregions, and the amygdala. There were no significant associations between systolic BPV and ALFF across the right/left whole brain or in the insular cortex in either group. Findings suggest a possible regional vulnerability to cerebrovascular dysfunction and short-term fluctuations in blood pressure. BPV may be an understudied risk factor for cerebrovascular changes in aging.

The impact of blood pressure variability on cognition: current limitations and new advances

Dementia is the most common neurodegenerative disease in the aging population. Emerging evidence indicates that blood pressure (BP) variability is correlated with cognitive impairment and dementia independent of mean BP levels. The state-of-the-art review summarizes the latest evidence regarding the impact of BP variability on cognition in cognitively intact populations, patients with mild cognitive impairment, and different dementia types, focusing on the important confounding factors and new advances. This review also summarizes the potential mechanisms underlying the relationship between BP variability and cognitive impairment, and dementia, briefly discussing sex differences in the relationship. At last, current limitations and future perspectives are discussed to optimize BP management in preventing cognitive impairment and dementia.

Blood Pressure Variability in Clinical Practice: Past, Present and the Future

Recent advances in wearable technology through convenient and cuffless systems will enable continuous, noninvasive monitoring of blood pressure (BP), heart rate, and heart rhythm on both longitudinal 24-hour measurement scales and high-frequency beat-to-beat BP variability and synchronous heart rate variability and changes in underlying heart rhythm. Clinically, BP variability is classified into 4 main types on the basis of the duration of monitoring time: very-short-term (beat to beat), short-term (within 24 hours), medium-term (within days), and long-term (over months and years). BP variability is a strong risk factor for cardiovascular diseases, chronic kidney disease, cognitive decline, and mental illness. The diagnostic and therapeutic value of measuring and controlling BP variability may offer critical targets in addition to lowering mean BP in hypertensive populations.

Challenges and opportunities of diagnostic markers of Alzheimer's disease based on structural magnetic resonance imaging

OBJECTIVES

This article aimed to carry out a narrative literature review of early diagnostic markers of Alzheimer's disease (AD) based on both micro and macro levels of pathology, indicating the shortcomings of current biomarkers and proposing a novel biomarker of structural integrity that associates the hippocampus and adjacent ventricle together. This could help to reduce the influence of individual variety and improve the accuracy and validity of structural biomarker.

METHODS

This review was based on presenting comprehensive background of early diagnostic markers of AD. We have compiled those markers into micro level and macro level, and discussed the advantages and disadvantages of them. Eventually the ratio of gray matter volume to ventricle volume was put forward.

RESULTS

The costly methodologies and related high patient burden of "micro" biomarkers (cerebrospinal fluid biomarkers) hinder the implementation in routine clinical examination. In terms of "macro" biomarkers- hippocampal volume (HV), there is a large variation of it among population, which undermines its validity Considering the gray matter atrophies while the adjacent ventricular volume enlarges, we assume the hippocampal to ventricle ratio (HVR) is a more reliable marker than HV alone the emerging evidence showed hippocampal to ventricle ratio predicts memory functions better than HV alone in elderly sample.

CONCLUSIONS

The ratio between gray matter structures and adjacent ventricular volumes counts as a promising superior diagnostic marker of early neurodegeneration.

Older Adults With Higher Blood Pressure Variability Exhibit Cerebrovascular Reactivity Deficits

BACKGROUND

Elevated blood pressure (BP) variability is predictive of increased risk for stroke, cerebrovascular disease, and other vascular brain injuries, independent of traditionally studied average BP levels. However, no studies to date have evaluated whether BP variability is related to diminished cerebrovascular reactivity, which may represent an early marker of cerebrovascular dysfunction presaging vascular brain injury.

METHODS

The present study investigated BP variability and cerebrovascular reactivity in a sample of 41 community-dwelling older adults (mean age 69.6 [SD 8.7] years) without a history of dementia or stroke. Short-term BP variability was determined from BP measurements collected continuously during a 5-minute resting period followed by cerebrovascular reactivity during 5-minute hypocapnia and hypercapnia challenge induced by visually guided breathing conditions. Cerebrovascular reactivity was quantified as percent change in cerebral perfusion by pseudo-continuous arterial spin labeling (pCASL)-MRI per unit change in end-tidal CO2.

RESULTS

Elevated systolic BP variability was related to lower whole brain cerebrovascular reactivity during hypocapnia (ß = -0.43 [95% CI -0.73, -0.12]; P = 0.008; adjusted R2 =.11) and hypercapnia (ß = -0.42 [95% CI -0.77, -0.06]; P = 0.02; adjusted R2 = 0.19).

CONCLUSIONS

Findings add to prior work linking BP variability and cerebrovascular disease burden and suggest BP variability may also be related to prodromal markers of cerebrovascular dysfunction and disease, with potential therapeutic implications.

Photobiomodulation for Hypertension and Alzheimer's Disease

Although the cause(s) of Alzheimer's disease in the majority of cases remains elusive, it has long been associated with hypertension. In animal models of the disease, hypertension has been shown to exacerbate Alzheimer-like pathology and behavior, while in humans, hypertension during mid-life increases the risk of developing the disease later in life. Unfortunately, once individuals are diagnosed with the disease, there are few therapeutic options available. There is neither an effective symptomatic treatment, one that treats the debilitating cognitive and memory deficits, nor, more importantly, a neuroprotective treatment, one that stops the relentless progression of the pathology. Further, there is no specific preventative treatment that offsets the onset of the disease. A key factor or clue in this quest for an effective preventative and therapeutic treatment may lie in the contribution of hypertension to the disease. In this review, we explore the idea that photobiomodulation, the application of specific wavelengths of light onto body tissues, can reduce the neuropathology and behavioral deficits in Alzheimer's disease by controlling hypertension. We suggest that treatment with photobiomodulation can be an effective preventative and therapeutic option for this neurodegenerative disease.

Use of blood pressure measurements extracted from the electronic health record in predicting Alzheimer's disease: A retrospective cohort study at two medical centers

INTRODUCTION

Studies investigating the relationship between blood pressure (BP) measurements from electronic health records (EHRs) and Alzheimer's disease (AD) rely on summary statistics, like BP variability, and have only been validated at a single institution. We hypothesize that leveraging BP trajectories can accurately estimate AD risk across different populations.

METHODS

In a retrospective cohort study, EHR data from Veterans Affairs (VA) patients were used to train and internally validate a machine learning model to predict AD onset within 5 years. External validation was conducted on patients from Michigan Medicine (MM).

RESULTS

The VA and MM cohorts included 6860 and 1201 patients, respectively. Model performance using BP trajectories was modest but comparable (area under the receiver operating characteristic curve [AUROC] = 0.64 [95% confidence interval (CI) = 0.54-0.73] for VA vs. AUROC = 0.66 [95% CI = 0.55-0.76] for MM).

CONCLUSION

Approaches that directly leverage BP trajectories from EHR data could aid in AD risk stratification across institutions.

Identification of genetic loci shared between Alzheimer's disease and hypertension

Alzheimer's disease (AD) and high blood pressure (BP) are prevalent age-related diseases with significant unexplained heritability. A thorough analysis of genetic pleiotropy between AD and BP will lay a foundation for the study of the associated molecular mechanisms, leading to a better understanding of the development of each phenotype. We used the conditional false discovery rate (cFDR) method to identify novel genetic loci associated with both AD and BP. The cFDR approach improves the effective sample size for association testing by combining GWAS summary statistics for correlated phenotypes. We identified 50 pleiotropic SNPs for AD and BP, 7 of which are novel and have not previously been reported to be associated with either AD or BP. The novel SNPs located at STK3 are particularly noteworthy, as this gene may influence AD risk via the Hippo signaling network, which regulates cell death. Bayesian colocalization analysis demonstrated that although AD and BP are associated, they do not appear to share the same causal variants. We further performed two sample Mendelian randomization analysis, but could not detect a causal effect of BP on AD. Despite the inability to establish a causal link between AD and BP, our findings report some potential novel pleiotropic loci that may influence disease susceptibility. In summary, we identified 7 SNPs that annotate to 4 novel genes which have not previously been reported to be associated with AD nor with BP and discuss the possible role of one of these genes, STK3 in the Hippo signaling network.

Blood pressure variability and plasma Alzheimer's disease biomarkers in older adults

Blood pressure variability is an emerging risk factor for Alzheimer's disease in older adults, independent of average blood pressure levels. Growing evidence suggests increased blood pressure variability is linked to Alzheimer's disease pathophysiology indexed by cerebrospinal fluid and positron emission tomography markers, but relationships with plasma Alzheimer's disease markers have not been investigated. In this cross-sectional study of 54 community-dwelling older adults (aged 55-88, mean age 69.9 [8.2 SD]), elevated blood pressure variability over 5 min was associated with lower levels of plasma Aβ_1-42 (standardized ß =  - 0.36 [95% CI - 0.61, - 0.12]; p = 0.005; adjusted R² = 0.28) and Aβ_1-42: Aβ_1-40 ratio (ß =  - 0.49 [95% CI - 0.71, - 0.22]; p < 0.001; adjusted R² = 0.28), and higher levels of total tau (ß = 0.27 [95% CI 0.01, 0.54]; p = 0.04; adjusted R² = 0.19) and Ptau₁₈₁:Aβ_1-42 ratio (ß = 0.26 [95% CI 0.02, 0.51]; p = 0.04; adjusted R² = 0.22). Findings suggest higher blood pressure variability is linked to plasma biomarkers of increased Alzheimer's disease pathophysiology.

The Influence of 24-h Ambulatory Blood Pressure on Cognitive Function and Neuropathological Biomarker in Patients With Alzheimer's Disease

Purpose

This study aimed to investigate the influence of 24-h ambulatory blood pressure (BP) on cognitive function and neuropathological biomarkers in patients with Alzheimer's disease (AD) at the stages of mild cognitive impairment (MCI) and dementia.

Methods

The patients with AD were divided into the MCI (AD-MCI) group and the dementia (AD-D) group. Notably, 24-h BP variables, including BP level, coefficient of variation (CV) of BP, and pulse pressure, were collected and compared between the two groups. The correlations between 24-h BP variables and the scores of cognitive domains were analyzed. The independent influencing factors of cognitive domains of patients with AD were investigated. The levels of neuropathological biomarkers of AD, including β amyloid (Aβ)1−42, phosphorylated tau (P-tau), and total tau (T-tau), in cerebrospinal fluid (CSF) were measured and compared between the two groups, and the correlations between 24-h BP variables and the levels of neuropathological biomarkers of AD were analyzed.

Results

Daytime CV of systolic BP (SBP) was significantly increased in the AD-D group compared to that in the AD-MCI group. The 24-h and daytime CV of SBP and ambulatory pulse pressure were significantly and negatively correlated with memory score. The average 24-h and average daytime SBP level and CV of SBP, daytime CV of diastolic BP (DBP), and 24-h, daytime, and night-time ambulatory pulse pressure were significantly and negatively correlated with language score. The average 24-h SBP level, daytime CV of SBP, and 24-h, daytime, and night-time ambulatory pulse pressure were significantly and negatively correlated with attention score. Further analysis indicated that daytime CV of SBP as well as age and course of disease were the independent influencing factors of language. Age was also the independent influencing factor of memory and attention of patients with AD. T-tau level in CSF in the AD-D group was significantly higher than that in the AD-MCI group, but the levels of Aβ1−42, P-tau, and T-tau in CSF were not correlated with 24-h ambulatory BP variables.

Conclusion

Daytime CV of SBP was the independent influencing factor of language in patients with AD. The AD-D patients had significantly severe neurodegeneration than AD-MCI patients, which was, however, not through the influence of 24-h ambulatory BP variables on neuropathological biomarkers of AD.

Recent Advances Towards Diagnosis and Therapeutic Fingerprinting for Alzheimer's Disease

Since the report of "a peculiar severe disease process of the cerebral cortex" by Alois Alzheimer in 1906, it was considered to be a rare condition characterized by loss of cognition, memory impairment, and pathological markers such as senile plaques or neurofibrillary tangles (NFTs). Later on, the report was published in the textbook "Psychiatrie" and the disease was named as Alzheimer's disease (AD) and was known to be the consequences of aging; however, owing to its complex etiology, there is no cure for the progressive neurodegenerative disorder. Our current understanding of the mechanisms involved in the pathogenesis of AD is still at the mechanistic level. The treatment strategies applied currently only alleviate the symptoms and co-morbidities. For instance, the available treatments such as the usage of acetylcholinesterase inhibitors and N-methyl D-aspartate antagonists have minimal impact on the disease progression and target the later aspects of the disease. The recent advancements in the last two decades have made us more clearly understand the pathophysiology of the disease which has led to the development of novel therapeutic strategies. This review gives a brief idea about the various facets of AD pathophysiology and its management through modern investigational therapies to give a new direction for development of targeted therapeutic measures.

Anthocyanin as a therapeutic in Alzheimer's disease: A systematic review of preclinical evidences

BACKGROUND

The aim of this systematic review is to ponder the possible mechanism of action of anthocyanin in Alzheimer's disease (AD), to prompt the development of anthocyanin-based dietary supplementation or therapeutic intervention for AD and to explore the natural sources of anthocyanins.

METHODS

Electronic bibliographic databases such as PubMed, ScienceDirect, Proquest, DOAJ, Scopus, and Google Scholar were searched for preclinical studies probing the efficacy of anthocyanin on AD. The search strategy included no time limit, but was restricted to English. The review protocol is registered on PROSPERO, registration no. CRD42021272972. The systematic review followed the PICO approach for inclusion of reports. All the reports were appraised for risk of bias using the SYRCLE's RoB tool.

RESULTS

Bibliographic details of the article, animal strain/weight/age, induction model, anthocyanin source, type of anthocyanin, dose, route of administration, duration, and the outcome measures were extracted from 12 retrieved reports explicitly. The implication of food-based anthocyanin in acute and long-term cognition and Aβ mediated neurodegeneration appears alluring. Majority of the studies comprehended in this review had moderate methodological quality.

DISCUSSION

Efficacy of anthocyanin in alleviating oxidative stress, reactive astrogliosis, cholinergic dysfunction, apoptosis, synaptotoxicity, neuroinflammation, tau hyperphosphorylation, dysregulated membrane potential, neuronal extracellular calcium, dysfunctional amyloidogenic pathway, and cognitive deficits in various rodent models of AD is manifested compositely in 12 studies.

Alzheimer’s Disease: Epidemiology and Clinical Progression

Alzheimer’s disease (AD) is prevalent throughout the world and is the leading cause of dementia in older individuals (aged ≥ 65 years). To gain a deeper understanding of the recent literature on the epidemiology of AD and its progression, we conducted a review of the PubMed-indexed literature (2014–2021) in North America, Europe, and Asia. The worldwide toll of AD is evidenced by rising prevalence, incidence, and mortality due to AD—estimates which are low because of underdiagnosis of AD. Mild cognitive impairment (MCI) due to AD can ultimately progress to AD dementia; estimates of AD dementia etiology among patients with MCI range from 40% to 75% depending on the populations studied and whether the MCI diagnosis was made clinically or in combination with biomarkers. The risk of AD dementia increases with progression from normal cognition with no amyloid-beta (Aβ) accumulation to early neurodegeneration and subsequently to MCI. For patients with Aβ accumulation and neurodegeneration, lifetime risk of AD dementia has been estimated to be 41.9% among women and 33.6% among men. Data on progression from preclinical AD to MCI are sparse, but an analysis of progression across the three preclinical National Institute on Aging and Alzheimer’s Association (NIA-AA) stages suggests that NIA-AA stage 3 (subtle cognitive decline with AD biomarker positivity) could be useful in combination with other tools for treatment decision-making. Factors shown to increase risk include lower Mini-Mental State Examination (MMSE) score, higher Alzheimer’s Disease Assessment Scale (ADAS-cog) score, positive APOE4 status, white matter hyperintensities volume, entorhinal cortex atrophy, cerebrospinal fluid (CSF) total tau, CSF neurogranin levels, dependency in instrumental activities of daily living (IADL), and being female. Results suggest that use of biomarkers alongside neurocognitive tests will become an important part of clinical practice as new disease-modifying therapies are introduced.

Visit-to-Visit Blood Pressure Variability and Longitudinal Tau Accumulation in Older Adults

BACKGROUND

Elevated blood pressure variability (BPV) is predictive of dementia, independent of average blood pressure levels, but neuropathological mechanisms remain unclear. We examined whether BPV in older adults is related to tau accumulation in brain regions vulnerable to Alzheimer disease and whether relationships are modified by apoϵ4 carrier status.

METHODS

Two hundred eighty-six Alzheimer's Disease Neuroimaging Initiative participants without history of dementia underwent 3 to 4 blood pressure measurements over 12 months and ≥1 tau positron emission tomography thereafter. BPV was calculated as variability independent of mean. Each scan determined tau burden (standardized uptake value ratio) for a temporal meta-region of interest, including burden from entorhinal cortex, amygdala, parahippocampus, fusiform, inferior temporal, and middle temporal. Bayesian linear growth modeling examined the role of BPV, apolipoprotein ϵ4 carrier status, and time on regional tau accumulation after controlling for several variables, including baseline hypertension.

RESULTS

Elevated BPV was related to tau accumulation at follow-up in a temporal meta-region, independent of average blood pressure levels (ß, 0.89 [95% credible interval, 0.86-0.92]) and especially in entorhinal cortex (ß, 2.57 [95% credible interval, 2.15-2.99]). Apoϵ4 carriers with elevated BPV had the fastest tau accumulation at follow-up (ß, 1.73 [95% credible interval, 0.47-3.03]).

CONCLUSIONS

BPV is related to tau accumulation in brain regions vulnerable to Alzheimer disease, independent of average blood pressure. APOEϵ4 modified this relationship. Bidirectionality of findings is possible. BPV may represent a marker of vascular dysfunction related to early-stage tau pathology contributing to Alzheimer disease.

Selective vulnerability of medial temporal regions to short-term blood pressure variability and cerebral hypoperfusion in older adults

Blood pressure variability is an emerging risk factor for stroke, cognitive impairment, and dementia, possibly through links with cerebral hypoperfusion. Recent evidence suggests visit-to-visit (e.g., over months, years) blood pressure variability is related to cerebral perfusion decline in brain regions vulnerable to Alzheimer's disease. However, less is known about relationships between short-term (e.g., < 24 hours) blood pressure variability and regional cerebral perfusion, and whether these relationships may differ by age. We investigated short-term blood pressure variability and concurrent regional cerebral microvascular perfusion in a sample of community-dwelling older adults without history of dementia or stroke and healthy younger adults. Blood pressure was collected continuously during perfusion MRI. Cerebral blood flow was determined for several brain regions implicated in cerebrovascular dysfunction in Alzheimer's disease. Elevated systolic blood pressure variability was related to lower levels of concurrent cerebral perfusion in medial temporal regions: hippocampus (β = -.60 [95% CI -.90, -.30]; p < .001), parahippocampal gyrus (β = -.57 [95% CI -.89, -.25]; p = .001), entorhinal cortex (β = -.42 [95% CI -.73, -.12]; p = .009), and perirhinal cortex (β = -.37 [95% CI -.72, -.03]; p = .04), and not in other regions, and in older adults only. Findings suggest a possible age-related selective vulnerability of the medial temporal lobes to hypoperfusion in the context of short-term blood pressure fluctuations, independent of average blood pressure, white matter hyperintensities, and gray matter volume, which may underpin the increased risk for dementia associated with elevated BPV.

MiR-29c-3p May Promote the Progression of Alzheimer's Disease through BACE1

The aim of this study was to explore the specific role of miR-29c-3p in Alzheimer's disease (AD). Animal models of AD were established by injecting streptozotocin (STZ) into mice through the lateral ventricle, while cell models of AD were induced by 10 μM β-amyloid (Aβ). We detected miR-29c-3p and β-site amyloid precursor protein cleaving enzyme 1 (BACE1) contents and measured AD cell proliferation and apoptosis. A low miR-29c-3p level and a high BACE1 level were detected in the brain tissue of AD animal models and AD cell models. Aβ-processed cells had markedly lower proliferation activity, higher apoptosis, increased phosphorylation of tau protein was over phosphorylated, but the overexpression of miR-29c-3p or the silencing of BACE1 significantly enhanced the cell proliferation activity and reduced cell apoptosis by regulating the contents of related proteins. Inhibition of miR-29c-3p or overexpression of BACE1 aggravated Aβ-induced side effects. We used Targetscan7.2 to predict the downstream target genes of miR-29c-3p. Then, we detected that there were target binding sites between miR-29c-3p and BACE1. The rescue experiment identified BACE1 as a functional target for miR-29c-3p. AD leads to decreased miR-29c-3p level and increased BACE1 level. MiR-29c-3p has specific binding sites with the 3′-untranslated region (3′-UTR) of BACE1 and thus negatively regulates the BACE1 level, thereby affecting the progression of AD.

Day-To-Day Home Blood Pressure Variability and All-Cause Mortality in a Memory Clinic Population

BACKGROUND

High day-to-day blood pressure variability (BPV) has been associated with an increased risk for cognitive decline and mortality in the general population. Whether BPV is associated with increased all-cause mortality in older people with cognitive impairment is unknown.

OBJECTIVE

To investigate the association between day-to-day home BPV and all-cause mortality in older patients attending a memory clinic.

METHODS

We included 279 patients attending a memory clinic, who measured home blood pressure (BP) for 7 consecutive days in the morning and evening. Within-subject BPV was defined as the variation independent of the mean (VIM). Time-to-death was verified through the Dutch population registry. Cox proportional hazard regression was used. Separate analyses were performed for morning-to-morning and evening-to-evening BPV.

RESULTS

Mean age was 73±9 years, dementia and mild cognitive impairment were diagnosed in 35% and 34% respectively, and mean home BP was 139/79 mmHg. After a mean follow-up of 3.2 years, 52 patients had died. Neither day-to-day systolic nor diastolic VIM were associated with mortality (adjusted hazard ratio [HR] systolic VIM: 0.99, 95% -CI 0.92-1.06, p = 0.770, HR diastolic VIM: 1.04, 95% -CI 0.93-1.17, p = 0.517). When morning and evening measurements were analyzed separately, systolic morning-to-morning VIM was associated with mortality (adjusted HR: 1.09, 95% -CI 1.01-1.18, p = 0.033).

CONCLUSION

In this study, day-to-day BPV was not associated with all-cause mortality in patients attending a memory clinic. However, morning-to-morning BPV was. Due to the short assessment window, there is still a lack of clarity; hence future research is warranted to clarify the role of all BPV components in aging.

Cerebral Small Vessel Disease in Sporadic and Familial Alzheimer Disease

Alzheimer disease (AD) is the most common cause of dementia. Biological definitions of AD are limited to the cerebral burden of amyloid β plaques, neurofibrillary pathology, and neurodegeneration. However, current evidence suggests that various features of small vessel disease (SVD) are part of and covertly modify both sporadic and familial AD. Neuroimaging studies suggest that white matter hyperintensities explained by vascular mechanisms occurs frequently in the AD spectrum. Recent advances have further emphasized that frontal periventricular and posterior white matter hyperintensities are associated with cerebral amyloid angiopathy in familial AD. Although whether SVD markers precede the classically recognized biomarkers of disease is debatable, post-mortem studies show that SVD pathology incorporating small cortical and subcortical infarcts, microinfarcts, microbleeds, perivascular spacing, and white matter attenuation is commonly found in sporadic as well as in mutation carriers with confirmed familial AD. Age-related cerebral vessel pathologies such as arteriolosclerosis and cerebral amyloid angiopathy modify progression or worsen risk by shifting the threshold for cognitive impairment and AD dementia. The incorporation of SVD as a biomarker is warranted in the biological definition of AD. Therapeutic interventions directly reducing the burden of brain amyloid β have had no major impact on the disease or delaying cognitive deterioration, but lowering the risk of vascular disease seems the only rational approach to tackle both early- and late-onset AD dementia.

Digital Resilience Biomarkers for Personalized Health Maintenance and Disease Prevention

Health maintenance and disease prevention strategies become increasingly prioritized with increasing health and economic burden of chronic, lifestyle-related diseases. A key element in these strategies is the empowerment of individuals to control their health. Self-measurement plays an essential role in achieving such empowerment. Digital measurements have the advantage of being measured non-invasively, passively, continuously, and in a real-world context. An important question is whether such measurement can sensitively measure subtle disbalances in the progression toward disease, as well as the subtle effects of, for example, nutritional improvement. The concept of resilience biomarkers, defined as the dynamic evaluation of the biological response to an external challenge, has been identified as a viable strategy to measure these subtle effects. In this review, we explore the potential of integrating this concept with digital physiological measurements to come to digital resilience biomarkers. Additionally, we discuss the potential of wearable, non-invasive, and continuous measurement of molecular biomarkers. These types of innovative measurements may, in the future, also serve as a digital resilience biomarker to provide even more insight into the personal biological dynamics of an individual. Altogether, digital resilience biomarkers are envisioned to allow for the measurement of subtle effects of health maintenance and disease prevention strategies in a real-world context and thereby give personalized feedback to improve health.

Gender-specific clinical risk scores incorporating blood pressure variability for predicting incident dementia

INTRODUCTION

The present study examined the gender-specific prognostic value of blood pressure (BP) and its variability in the prediction of dementia risk and developed a score system for risk stratification.

MATERIALS AND METHODS

This was a retrospective, observational population-based cohort study of patients admitted to government-funded family medicine clinics in Hong Kong between January 1, 2000 and March 31, 2002 with at least 3 blood pressure measurements. Gender-specific risk scores for dementia were developed and tested.

RESULTS

The study consisted of 74 855 patients, of whom 3550 patients (incidence rate: 4.74%) developed dementia over a median follow-up of 112 months (IQR= [59.8-168]). Nonlinear associations between diastolic/systolic BP measurements and the time to dementia presentation were identified. Gender-specific dichotomized clinical scores were developed for males (age, hypertension, diastolic and systolic BP and their measures of variability) and females (age, prior cardiovascular, respiratory, gastrointestinal diseases, diabetes mellitus, hypertension, stroke, mean corpuscular volume, monocyte, neutrophil, urea, creatinine, diastolic and systolic BP and their measures of variability). They showed high predictive strengths for both male (hazard ratio [HR]: 12.83, 95% confidence interval [CI]: 11.15-14.33, P value < .0001) and female patients (HR: 26.56, 95% CI: 14.44-32.86, P value < .0001). The constructed gender-specific scores outperformed the simplified systems without considering BP variability (C-statistic: 0.91 vs 0.82), demonstrating the importance of BP variability in dementia development.

CONCLUSION

Gender-specific clinical risk scores incorporating BP variability can accurately predict incident dementia and can be applied clinically for early disease detection and optimized patient management.

The Pathogenesis and Treatment of Cardiovascular Autonomic Dysfunction in Parkinson's Disease: What We Know and Where to Go

Cardiovascular autonomic dysfunctions (CAD) are prevalent in Parkinson’s disease (PD). It contributes to the development of cognitive dysfunction, falls and even mortality. Significant progress has been achieved in the last decade. However, the underlying mechanisms and effective treatments for CAD have not been established yet. This review aims to help clinicians to better understand the pathogenesis and therapeutic strategies. The literatures about CAD in patients with PD were reviewed. References for this review were identified by searches of PubMed between 1972 and March 2021, with the search term “cardiovascular autonomic dysfunctions, postural hypotension, orthostatic hypotension (OH), supine hypertension (SH), postprandial hypotension, and nondipping”. The pathogenesis, including the neurogenic and non-neurogenic mechanisms, and the current pharmaceutical and non-pharmaceutical treatment for CAD, were analyzed. CAD mainly includes four aspects, which are OH, SH, postprandial hypotension and nondipping, among them, OH is the main component. Both non-neurogenic and neurogenic mechanisms are involved in CAD. Failure of the baroreflex circulate, which includes the lesions at the afferent, efferent or central components, is an important pathogenesis of CAD. Both non-pharmacological and pharmacological treatment alleviate CAD-related symptoms by acting on the baroreflex reflex circulate. However, pharmacological strategy has the limitation of failing to enhance baroreflex sensitivity and life quality. Novel OH treatment drugs, such as pyridostigmine and atomoxetine, can effectively improve OH-related symptoms via enhancing residual sympathetic tone, without adverse reactions of supine hypertension. Baroreflex impairment is a crucial pathological mechanism associated with CAD in PD. Currently, non-pharmacological strategy was the preferred option for its advantage of enhancing baroreflex sensitivity. Pharmacological treatment is a second-line option. Therefore, to find drugs that can enhance baroreflex sensitivity, especially via acting on its central components, is urgently needed in the scientific research and clinical practice.

Regulation of cerebral blood flow in humans: physiology and clinical implications of autoregulation

Brain function critically depends on a close matching between metabolic demands, appropriate delivery of oxygen and nutrients, and removal of cellular waste. This matching requires continuous regulation of cerebral blood flow (CBF), which can be categorized into four broad topics: 1) autoregulation, which describes the response of the cerebrovasculature to changes in perfusion pressure; 2) vascular reactivity to vasoactive stimuli [including carbon dioxide (CO2)]; 3) neurovascular coupling (NVC), i.e., the CBF response to local changes in neural activity (often standardized cognitive stimuli in humans); and 4) endothelium-dependent responses. This review focuses primarily on autoregulation and its clinical implications. To place autoregulation in a more precise context, and to better understand integrated approaches in the cerebral circulation, we also briefly address reactivity to CO2 and NVC. In addition to our focus on effects of perfusion pressure (or blood pressure), we describe the impact of select stimuli on regulation of CBF (i.e., arterial blood gases, cerebral metabolism, neural mechanisms, and specific vascular cells), the interrelationships between these stimuli, and implications for regulation of CBF at the level of large arteries and the microcirculation. We review clinical implications of autoregulation in aging, hypertension, stroke, mild cognitive impairment, anesthesia, and dementias. Finally, we discuss autoregulation in the context of common daily physiological challenges, including changes in posture (e.g., orthostatic hypotension, syncope) and physical activity.

Blood pressure variability and medial temporal atrophy in apolipoprotein ϵ4 carriers

Blood pressure variability is an emerging risk factor for dementia but relationships with markers of neurodegeneration and Alzheimer's disease risk are understudied. We investigated blood pressure variability over one year and follow-up medial temporal brain volume change in apolipoprotein ϵ4 carriers and non-carriers, and in those with and without Alzheimer's disease biomarker abnormality. 1051 Alzheimer's Disease Neuroimaging Initiative participants without history of dementia or stroke underwent 3-4 blood pressure measurements over 12 months and ≥ 1 MRI thereafter. A subset (n = 252) underwent lumbar puncture to determine Alzheimer's disease cerebral spinal fluid amyloid-beta and phosphorylated tau biomarker abnormality. Blood pressure variability over 12 months was calculated as variability independent of mean. Longitudinal hippocampal and entorhinal cortex volume data were extracted from serial brain MRI scans obtained after the final blood pressure measurement. Apolipoprotein ϵ4 carrier status was defined as at least one ϵ4 allele. Bayesian growth modelling revealed a significant interaction of blood pressure variability by ϵ4 by time on hippocampal (ß: -2.61 [95% credible interval -3.02, -2.12]) and entorhinal cortex (ß: -1.47 [95% credible interval -1.71, -1.17]) volume decline. A similar pattern emerged in subsets with Alzheimer's disease pathophysiology (i.e., abnormal levels of both amyloid-beta and phosphorylated tau). Findings suggest that elevated blood pressure variability is related to medial temporal volume loss specifically in ϵ4 carriers, and in those with Alzheimer's disease biomarker abnormality. Findings could implicate blood pressure variability in medial temporal neurodegeneration observed in older ϵ4 carriers and those with prodromal Alzheimer's disease.

Achieving brain clearance and preventing neurodegenerative diseases-A glymphatic perspective

Age-related neurodegenerative diseases are a growing burden to society, and many are sporadic, meaning that the environment, diet and lifestyle play significant roles. Cerebrospinal fluid (CSF)-mediated clearing of brain waste products via perivascular pathways, named the glymphatic system, is receiving increasing interest, as it offers unexplored perspectives on understanding neurodegenerative diseases. The glymphatic system is involved in clearance of metabolic by-products such as amyloid-β from the brain, and its function is believed to lower the risk of developing some of the most common neurodegenerative diseases. Here, we present magnetic resonance imaging (MRI) data on the heart cycle's control of CSF flow in humans which corroborates findings from animal studies. We also review the importance of sleep, diet, vascular health for glymphatic clearance and find that these factors are also known players in brain longevity.

Antemortem Visit-To-Visit Blood Pressure Variability Predicts Cerebrovascular Lesion Burden in Autopsy-Confirmed Alzheimer's Disease

BACKGROUND

Blood pressure variability is linked to Alzheimer's disease (AD) risk and MRI-based markers of cerebrovascular disease. Less is known about the role of blood pressure variability in postmortem evaluation of cerebrovascular disease and AD.

OBJECTIVE

To determine whether antemortem blood pressure variability predicts cerebrovascular and AD pathology and follow-up cognitive change in autopsy-confirmed AD.

METHODS

National Alzheimer's Coordinating Center participants (n = 513) underwent 3-4 approximately annual blood pressure measurements and were confirmed to have AD at postmortem evaluation. A subset (n = 493) underwent neuropsychological evaluation at follow-up. Regression models examined relationships between blood pressure variability and cerebrovascular and AD pathological features and follow-up cognitive change.

RESULTS

Elevated blood pressure variability predicted increased postmortem cerebrovascular lesion burden (ß = 0.26 [0.10, 0.42]; p = 0.001; R2 = 0.12). Increased blood pressure variability predicted specific cerebrovascular lesion severity, including atherosclerosis in the Circle of Willis (OR = 1.22 [1.03, 1.44]; p = 0.02) and cerebral arteriolosclerosis (OR = 1.32 [1.04, 1.69]; p = 0.03). No significant relationships were observed between blood pressure variability and AD pathological findings, including Braak & Braak stage, neuritic plaques or diffuse plaques, or cerebral amyloid angiopathy, or follow-up cognitive decline.

CONCLUSION

Findings suggest that elevated blood pressure variability is related to postmortem cerebrovascular lesion burden in autopsy-confirmed AD, independent of average blood pressure and AD neuropathology. Blood pressure fluctuation may selectively promote atherosclerotic and arteriolosclerotic brain lesions with potential implications for cognitive impairment and dementia.

Ambulatory Blood Pressure Characteristics of Patients with Alzheimer's Disease: A Multicenter Study from China

BACKGROUND

Previous studies revealed that abnormal blood pressure (BP) plays an important role in the pathogenesis of Alzheimer's disease (AD). However, little is known about the ambulatory BP characteristics of AD in the mild or severe stage.

OBJECTIVE

We explored the ambulatory BP characteristics of AD in the mild or severe stage.

METHODS

In the present study, 106 AD patients (42.5%male, average age 81.6 years) were enrolled from three centers in China. Clinal BP measurements at the supine and standing positions, neurological evaluations, and the 24 h ambulatory BP monitoring were performed.

RESULTS

In the 106 AD patients, 49.2%, 36.8%, and 70%of patients had 24 h, daytime, and nighttime systolic hypertension, respectively, while 19.8%, 29.2%, and 5.7%had 24 h, daytime, and nighttime diastolic hypotension. The prevalence of the reduced and reverse dipping pattern was 34.0%and 48.1%for systolic BP and 32.1%and 45.3%for diastolic BP, respectively. The daytime diastolic BP was significantly correlated with cognitive performance. After adjustment for age, sex, and body mass index, only daytime diastolic BP was associated with remarkable cognitive deterioration (p≤0.008). Further, AD patients in the severe stage had significantly lower levels of the 24 h, daytime, and nighttime diastolic BP, compared with those in the mild stage.

CONCLUSION

In general, AD patients were featured with high nighttime systolic BP, low daytime diastolic BP, and abnormal circadian BP rhythm of reduced and reverse dipping. The diastolic BP, especially daytime diastolic BP, was adversely correlated with the cognitive deterioration in AD.

Association between Blood Pressure, Blood Pressure Variability, and Post-Stroke Cognitive Impairment

After stroke, dynamic changes take place from necrotic-apoptotic continuum, inflammatory response to poststroke neurogenesis, and remodeling of the network. These changes and baseline brain pathology such as small vessel disease (SVD) and amyloid burden may be associated with the occurrence of early or late poststroke cognitive impairment (PSCI) or dementia (PSD), which affect not only stroke victims but also their families and even society. We reviewed the current concepts and understanding of the pathophysiology for PSCI/PSD and identified useful tools for the diagnosis and the prediction of PSCI in serological, CSF, and image characteristics. Then, we untangled their relationships with blood pressure (BP) and blood pressure variability (BPV), important but often overlooked risk factors for PSCI/PSD. Finally, we provided evidence for the modifying effects of BP and BPV on PSCI as well as pharmacological and non-pharmacological interventions and life style modification for PSCI/PSD prevention and treatment.

Long-Term Blood Pressure Variability and Risk of Cognitive Decline and Dementia Among Older Adults

Background

Blood pressure variability (BPV) in midlife increases risk of late‐life dementia, but the impact of BPV on the cognition of adults who have already reached older ages free of major cognitive deficits is unknown. We examined the risk of incident dementia and cognitive decline associated with long‐term, visit‐to‐visit BPV in a post hoc analysis of the ASPREE (Aspirin in Reducing Events in the Elderly) trial.

Methods and Results

ASPREE participants (N=19 114) were free of dementia and significant cognitive impairment at enrollment. Measurement of BP and administration of a standardized cognitive battery evaluating global cognition, delayed episodic memory, verbal fluency, and processing speed and attention occurred at baseline and follow‐up visits. Time‐to‐event analysis using Cox proportional hazards regression models were used to calculate hazard ratios (HR) and corresponding 95% CI for incident dementia and cognitive decline, according to tertile of SD of systolic BPV. Individuals in the highest BPV tertile compared with the lowest had an increased risk of incident dementia and cognitive decline, independent of average BP and use of antihypertensive drugs. There was evidence that sex modified the association with incident dementia (interaction P=0.02), with increased risk in men (HR, 1.68; 95% CI, 1.19–2.39) but not women (HR, 1.01; 95% CI, 0.72–1.42). For cognitive decline, similar increased risks were observed for men and women (interaction P=0.15; men: HR, 1.36; 95% CI, 1.16–1.59; women: HR, 1.14; 95% CI, 0.98–1.32).

Conclusions

High BPV in older adults without major cognitive impairment, particularly men, is associated with increased risks of dementia and cognitive decline.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01038583; isrctn.com. Identifier: ISRCTN83772183.

Tau pathologies mediate the association of blood pressure with cognitive impairment in adults without dementia: The CABLE study

INTRODUCTION

This study delineated the interrelationships among blood pressure (BP), cerebrospinal fluid (CSF) core biomarkers of Alzheimer's disease (AD), and cognition.

METHODS

The linear regression analyses were conducted in 1546 non-demented participants (mean age of 61.58 years, range 40 to 89 years; 40% female; average days of BP measurement, 9.10 days). Mediation analyses with 10,000 bootstrapped iterations were used to explore the mediation effects.

RESULTS

A clear age-related pattern of BP was delineated. Mid-life hypertension (especially systolic BP), late-life lower diastolic BP, as well as mid- and late-life higher pulse pressure were associated with cognitive impairment and tau-related biomarkers. BP variability was associated only with cognition but not with CSF biomarkers. Overall, the associations between BP and cognition were partially mediated (proportion: 11% to 30%) by tau pathologies, independently of amyloid pathology.

DISCUSSION

Tau pathologies might play important roles in the relationship between BP and cognition, with significant age- and BP-type dependences.

Day-to-Day Home Blood Pressure Variability is Associated with Cerebral Small Vessel Disease Burden in a Memory Clinic Population

BACKGROUND

High visit-to-visit blood pressure variability (BPV) has been associated with cognitive decline and cerebral small vessel disease (cSVD), in particular cerebrovascular lesions. Whether day-to-day BPV also relates to cSVD has not been investigated.

OBJECTIVE

To investigate the cross-sectional association between day-to-day BPV and total cSVD MRI burden in older memory clinic patients.

METHODS

We included outpatients referred to our memory clinic, who underwent cerebral MRI as part of their diagnostic assessment. We determined the validated total cSVD score (ranging from 0-4) by combining four markers of cSVD that were visually rated. Home blood pressure (BP) measurements were performed for one week, twice a day, according to international guidelines. BPV was defined as the within-subject coefficient of variation (CV; standard deviation/mean BP*100). We used multivariable ordinal logistic regression analyses adjusted for age, sex, smoking, diabetes, antihypertensive medication, history of cardiovascular disease, and mean BP.

RESULTS

For 82 patients (aged 71.2±7.9 years), mean home BP was 140/79±15/9 mmHg. Dementia and mild cognitive impairment were diagnosed in 46% and 34%, respectively. 78% had one or more markers of cSVD. Systolic CV was associated with cSVD burden (adjusted odds ratio per point increase in CV = 1.29, 95% confidence interval = 1.04-1.60, p = 0.022). There were no differences in diastolic CV and mean BP between the cSVD groups. When we differentiated between morning and evening BP, only evening BPV remained significantly associated with total cSVD burden.

CONCLUSION

Day-to-day systolic BPV is associated with cSVD burden in memory clinic patients. Future research should indicate whether lowering BPV should be included in BP management in older people with memory complaints.

Visit-to-visit blood pressure variability and regional cerebral perfusion decline in older adults

Blood pressure variability (BPV) is linked to dementia risk, possibly through cerebral hypoperfusion. We investigated BPV over 1 year and concurrent regional cerebral perfusion decline in older adults without dementia. Participants underwent 4 blood pressure measurements across 12 months, ASL-MRI at baseline and 12-months, and baseline FDG-PET. Regional perfusion was normalized to precentral gyrus. A subset had cerebral spinal fluid Alzheimer's disease biomarker abnormalities. For every SD increase in BPV, perfusion decreased in medial orbitofrontal cortex (ß = -.36; p = 0.008), hippocampus (ß = -.37; p = 0.005), entorhinal cortex (ß = -.48; p < 0.001), precuneus (ß = -.31; p = 0.02), inferior parietal cortex (ß = -.44; p < 0.001), and inferior temporal cortex (ß = -.46; p < 0.001). Similar patterns emerged in subsets with biomarker abnormalities. Older adults with elevated BPV exhibit concurrent regional perfusion decline in areas vulnerable to Alzheimer's disease, independent of cerebral hypometabolism. BPV may be an early marker of vascular dysfunction in aging.

Olmesartan Prevents Oligomerized Amyloid β (Aβ)-Induced Cellular Senescence in Neuronal Cells

Alzheimer's disease (AD) is a neurodegenerative disease with high morbidity. The deposition of oligomerized amyloid β (Aβ) is the pathological feature of AD. The Aβ-caused neuronal oxidative stress and cellular senescence play an important role in the development and progression of AD. Olmesartan is a novel angiotensin receptor blocker with promising antihypertensive properties and has recently been reported to exert anti-inflammatory and antioxidative stress effects. Blood pressure control using Angiotensin receptor blockers has shown multiple benefits in Alzheimer's disease models. In the present study, the effect of Olmesartan on oligomerized amyloid β (Aβ)-induced cellular senescence was investigated in cultured M17 neuronal cells. Our results show that Olmesartan treatment significantly ameliorates oligomerized Aβ-elevated ROS and MDA levels, as well as the induced senescent cells number. At the molecular level, Olmesartan inhibits the elevated expression of senescence biomarkers (p16 and p21). Furthermore, Olmesartan potently reversed the increased K382 acetylation of p53 and the downregulation of SIRT1. Moreover, we show that the effect of Olmesartan against cell senescence and deacetylation of p53 was abolished by inhibition of SIRT1, either by using nicotinamide or by transfection with SIRT1 siRNA. In conclusion, Olmesartan prevents oligomerized Aβ-induced cellular senescence in neuronal cells by downregulating p16 and p21 through a SIRT1 dependent deacetylation of p53; our finding indicates that Olmesartan has a protective effect in Aβ-induced neurotoxicity.

Hypertension and Alzheimer's disease: is the picture any clearer?

PURPOSE OF REVIEW

The relationship between hypertension and Alzheimer's disease (AD) is complex and varies across the lifespan. Studies have suggested that midlife hypertension is a risk factor for AD, although studies of late life hypertension have suggested that it either has no effect or a weak protective effect.

RECENT FINDINGS

Animal models of induced and spontaneous hypertension have found that AD pathological change (β-amyloid plaques and tau tangles) occurs within weeks of a hypertensive insult. Human imaging and autopsy studies indicate that midlife and late life hypertension are associated with increased AD pathological change. Meta-analyses of longitudinal studies indicate that midlife rather than late life hypertension is a risk factor for AD. New areas of research have suggested that rather than mean blood pressure (BP), it is the negative BP trajectories or the variability of BP that contributes to AD. In a number of meta-analyses of antihypertensive medications and their effect on AD, there were weak associations between improved AD outcomes and treatment.

SUMMARY

The combined analysis of animal, human clinical/pathological, epidemiological and drug trial data indicates that hypertension increases the risk of AD and treatment of hypertension may be an appropriate preventive measure.

Orthostatic Blood Pressure Recovery Is Associated With the Rate of Cognitive Decline and Mortality in Clinical Alzheimer's Disease

Background

Impaired recovery of blood pressure (BP) after standing has been shown to be related to cognitive function and mortality in people without dementia, but its role in people with Alzheimer’s disease (AD) is unknown. The aim of this study was to investigate the association of the orthostatic BP response with cognitive decline and mortality in AD.

Methods

In this post hoc analysis of a randomized controlled trial (Nilvad), we measured the beat-to-beat response of BP upon active standing in mild-to-moderate AD. This included the initial drop (nadir within 40 seconds) and recovery after 1 minute, both expressed relative to resting values. We examined the relationship between a small or large initial drop (median split) and unimpaired (≥100%) or impaired recovery (<100%) with 1.5-year change in Alzheimer’s Disease Assessment—cognitive subscale (ADAS-cog) scores and all-cause mortality.

Results

We included 55 participants (age 73.1 ± 6.2 years). Impaired BP recovery was associated with higher increases in ADAS-cog scores (systolic: β [95% confidence interval] = 5.6 [0.4–10.8], p = .035; diastolic: 7.6 [2.3–13.0], p = .006). During a median follow-up time of 49 months, 20 participants died. Impaired BP recovery was associated with increased mortality (systolic: HR [95% confidence interval] = 2.9 [1.1–7.8], p = .039; diastolic: HR [95% confidence interval] = 5.5 [1.9–16.1], p = .002). The initial BP drop was not associated with any outcome. Results were adjusted for age, sex, and intervention group.

Conclusions

Failure to fully recover BP after 1 minute of standing is associated with cognitive decline and mortality in AD. As such, BP recovery can be regarded as an easily obtained marker of progression rate of AD.

Glucose-Dementia Association Is Consistent Over Blood Pressure/Antihypertensive Groups

BACKGROUND

Higher glucose levels are associated with dementia risk in people with and without diabetes. However, little is known about how this association might vary by hypertension status and antihypertensive treatment. Most studies on modifiable dementia risk factors consider each factor in isolation.

OBJECTIVE

To test the hypothesis that hypertension and antihypertensive treatments may modify associations between glucose levels and dementia.

METHODS

Analyses of data generated from a research study and clinical care of participants from a prospective cohort of dementia-free older adults, including glucose measures, diabetes and antihypertensive treatments, and blood pressure data. We defined groups based on blood pressure (hypertensive versus not, ≥140/90 mmHg versus <140/90 mmHg) and antihypertensive treatment intensity (0, 1, or ≥2 classes of antihypertensives). We used Bayesian joint models to jointly model longitudinal exposure and time to event data.

RESULTS

A total of 3,056 participants without diabetes treatment and 480 with diabetes treatment were included (mean age at baseline, 75.1 years; mean 7.5 years of follow-up). Higher glucose levels were associated with greater dementia risk among people without and with treated diabetes. Hazard ratios for dementia were similar across all blood pressure/antihypertensive treatment groups (omnibus p = 0.82 for people without and p = 0.59 for people with treated diabetes).

CONCLUSION

Hypertension and antihypertensive treatments do not appear to affect the association between glucose and dementia risk in this population-based longitudinal cohort study of community-dwelling older adults. Future studies are needed to examine this question in midlife and by specific antihypertensive treatments.

Routine assessment of cognitive function in older patients with hypertension seen by primary care physicians: why and how-a decision-making support from the working group on 'hypertension and the brain' of the European Society of Hypertension and from the European Geriatric Medicine Society

: The guidelines on hypertension recently published by the European Societies of Hypertension and Cardiology, have acknowledged cognitive function (and its decline) as a hypertension-mediated organ damage. In fact, brain damage can be the only hypertension-mediated organ damage in more than 30% of hypertensive patients, evolving undetected for several years if not appropriately screened; as long as undetected it cannot provide either corrective measures, nor adequate risk stratification of the hypertensive patient.The medical community dealing with older hypertensive patients should have a simple and pragmatic approach to early identify and precisely treat these patients. Both hypertension and cognitive decline are undeniably growing pandemics in developed or epidemiologically transitioning societies. Furthermore, there is a clear-cut connection between exposure to the increased blood pressure and development of cognitive decline.Therefore, a group of experts in the field from the European Society of Hypertension and from the European Geriatric Medicine Society gathered together to answer practical clinical questions that often face the physician when dealing with their hypertensive patients in a routine clinical practice. They elaborated a decision-making approach to help standardize such clinical evaluation.

Blood Pressure Variability and Dementia: A State-of-the-Art Review

Accumulating evidence demonstrates that blood pressure variability (BPV) may contribute to target organ damage, causing coronary heart disease, stroke, and renal disease independent of the level of blood pressure (BP). Several lines of evidence have also linked increased BPV to a higher risk of cognitive decline and incident dementia. The estimated number of dementia cases worldwide is nearly 50 million, and this number continues to grow with increasing life expectancy. Because there is no effective treatment to modify the course of dementia, targeting modifiable vascular factors continues as a top priority for dementia prevention. A clear understanding of the role of BPV in dementia may shed light on the etiology, early prevention, and novel therapeutic targets of dementia, and has therefore gained substantial attention from researchers and clinicians. This review summarizes state-of-art evidence on the relationship between BPV and dementia, with a specific focus on the epidemiological evidence, the underlying mechanisms, and potential intervention strategies. We also discuss challenges and opportunities for future research to facilitate optimal BP management and the clinical translation of BPV for the risk assessment and prevention of dementia.

The Association Between Hypertension and Cognitive Impairment, and the Role of Antihypertensive Medications: A Literature Review

Vascular dementia (VD) is one of the leading causes of dementia, and hypertension is a known risk factor for VD. Hypertension treatment guidelines have previously discussed an optimal blood pressure goal to prevent further cardiovascular complications with long-term management. The treatment of hypertension can prevent stroke, kidney failure, and perhaps prevent cognitive decline as well. We reviewed studies that demonstrated an association between hypertension and cognitive impairment (CI). The role of antihypertensive medications (AHM) in preventing CI was also investigated. This topic is worth exploring as dementia has high healthcare costs and will become prominent as the population in the United States ages. We used the medical subject heading (MeSH) search strategy on Pubmed and reviewed 22 articles. The studies showed that there might be a link between hypertension, AHM, and CI. The studies did not suggest a superiority of any specific AHM class to prevent CI. Further research on optimal hypertension treatment goals to prevent cognitive impairment and dementia is recommended.