Visit-to-Visit Blood Pressure Variability and Alzheimer's Disease: Links and Risks

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.

Obstructive sleep apnea and non-dipper: epiphenomena or risks of Alzheimer's disease?: a review from the HOPE Asia Network

Obstructive sleep apnea (OSA) and associated nocturnal blood pressure (BP) surges is associated with non-dipper. On the other hand, the relationship between neurodegenerative diseases and non-dipper hypertension has been reported. To date, few studies have evaluated the relationships of nocturnal BP dipping patterns and OSA in relation to neurodegenerative diseases, particularly Alzheimer's disease (AD). This review examines the etiology of the association between OSA and the non-dipper pattern of hypertension and how both are involved in the development of AD. To set the stage for this review, we first focus on the pathophysiology of AD, which is interrelated with sleep apnea and non-dipper through dysregulation of central autonomic network.

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.

Blood pressure variability, central autonomic network dysfunction and cerebral small vessel disease in APOE4 carriers

Background

Increased blood pressure variability (BPV) is a risk factor for cerebral small vessel disease (CSVD) and neurodegeneration, independent of age and average blood pressure, particularly in apolipoprotein E4 (APOE4) carriers. However, it remains uncertain whether BPV elevation is a cause or a consequence of vascular brain injury, or to what degree injury to the central autonomic network (CAN) may contribute to BPV-associated risk in APOE4 carriers.

Methods

Independently living older adults (n=70) with no history of stroke or dementia were recruited from the community and underwent 5 minutes of resting beat-to-beat blood pressure monitoring, genetic testing, and brain MRI. Resting BPV, APOE genotype, CSVD burden on brain MRI, and resting state CAN connectivity by fMRI were analyzed. Causal mediation and moderation analysis evaluated BPV and CAN effects on CSVD in APOE4 carriers (n=37) and non-carriers (n=33).

Results

Higher BPV was associated with the presence and extent of CSVD in APOE4 carriers, but not non-carriers, independent of CAN connectivity (B= 18.92, P= .02), and CAN connectivity did not mediate the relationship between BPV and CSVD. In APOE4 carriers, CAN connectivity moderated the relationship between BPV and CSVD, whereby BPV effects on CSVD were greater in those with lower CAN connectivity (B= 36.43, P= .02).

Conclusions

Older APOE4 carriers with higher beat-to-beat BPV exhibit more extensive CSVD, independent of average blood pressure, and the strength of CAN connectivity does not mediate these effects. Findings suggest increased BPV is more likely a cause, not a consequence, of CSVD. BPV is more strongly associated with CSVD in APOE4 carriers with lower rsCAN connectivity, suggesting CAN dysfunction and BPV elevation may have synergistic effects on CSVD. Further studies are warranted to understand the interplay between BPV and CAN function in APOE4 carriers.

Biological Risk Factors Influencing Vascular Cognitive Impairments: A Review of the Evidence

Vascular cognitive impairment encompasses several types of deficits, ranging from mild cognitive impairment to dementia. Cognitive reserve refers to the brain's ability to balance damage and improve performance through certain types of brain networks. The purpose of this review was to assess the relationship between reserve in vascular impairment, specifically looking at whether cognitive impairment is influenced by cognitive reserve, identifying significant vascular risk factors and their pathological pathways. To achieve this purpose, a review covering these issues was conducted within the Embase, Cochrane, and PubMed database. A total of 657 scientific articles were found, and 33 papers were considered for the final analysis. We concluded that there is no consensus on the protective effects of brain reserve on cognitive impairment. Stroke and diabetes can be considered significant risk factors for vascular cognitive impairment, while hypertension is not as damaging as blood pressure variability, which structurally alters the brain through a variety of mechanisms.

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.

Blood Pressure Variability and Cerebral Perfusion Decline: A Post Hoc Analysis of the SPRINT MIND Trial

Background Blood pressure variability (BPV) is predictive of cerebrovascular disease and dementia, possibly though cerebral hypoperfusion. Higher BPV is associated with cerebral blood flow (CBF) decline in observational cohorts, but relationships in samples with strictly controlled blood pressure remain understudied. We investigated whether BPV relates to change in CBF in the context of intensive versus standard antihypertensive treatment. Methods and Results In this post hoc analysis of the SPRINT MIND (Systolic Blood Pressure Intervention Trial-Memory and Cognition in Decreased Hypertension) trial, 289 participants (mean, 67.6 [7.6 SD] years, 38.8% women) underwent 4 blood pressure measurements over a 9-month period after treatment randomization (intensive versus standard) and pseudo-continuous arterial spin labeling magnetic resonance imaging at baseline and ≈4-year follow-up. BPV was calculated as tertiles of variability independent of mean. CBF was determined for whole brain, gray matter, white matter, hippocampus, parahippocampal gyrus, and entorhinal cortex. Linear mixed models examined relationships between BPV and change in CBF under intensive versus standard antihypertensive treatment. Higher BPV in the standard treatment group was associated with CBF decline in all regions (ß comparing the first versus third tertiles of BPV in whole brain: -0.09 [95% CI, -0.17 to -0.01]; P=0.03), especially in medial temporal regions. In the intensive treatment group, elevated BPV was related to CBF decline only in the hippocampus (ß, -0.10 [95% CI, -0.18, -0.01]; P=0.03). Conclusions Elevated BPV is associated with CBF decline, especially under standard blood pressure-lowering strategies. Relationships were particularly robust in medial temporal regions, consistent with prior work using observational cohorts. Findings highlight the possibility that BPV remains a risk for CBF decline even in individuals with strictly controlled mean blood pressure levels. Registration URL: http://clinicaltrials.gov. Identifier: NCT01206062.

Visit-to-Visit Blood Pressure Variability and Cognitive Decline in Apolipoprotein ɛ4 Carriers versus Apolipoprotein ɛ3 Homozygotes

BACKGROUND

Blood pressure variability (BPV) is associated with cognitive decline and Alzheimer's disease (AD), but relationships with AD risk gene apolipoprotein (APOE) ɛ4 remain understudied.

OBJECTIVE

Examined the longitudinal relationship between BPV and cognitive change in APOE ɛ4 carriers and APOE ɛ3 homozygotes.

METHODS

1,194 Alzheimer's Disease Neuroimaging Initiative participants (554 APOE ɛ4 carriers) underwent 3-4 blood pressure measurements between study baseline and 12-month follow-up. Visit-to-visit BPV was calculated as variability independent of mean over these 12 months. Participants subsequently underwent ≥1 neuropsychological exam at 12-month follow-up or later (up to 156 months later). Composite scores for the domains of memory, language, executive function, and visuospatial abilities were determined. Linear mixed models examined the 3-way interaction of BPV×APOE ɛ4 carrier status x time predicting change in composite scores.

RESULTS

Higher systolic BPV predicted greater decline in memory (+1 SD increase of BPV: β= -0.001, p < 0.001) and language (β= -0.002, p < 0.0001) among APOE ɛ4 carriers, but not APOE ɛ3 homozygotes (memory: +1 SD increase of BPV: β= 0.0001, p = 0.57; language: β= 0.0001, p = 0.72). Systolic BPV was not significantly associated with change in executive function or visuospatial abilities in APOE ɛ4 carriers (ps = 0.08-0.16) or APOE ɛ3 homozygotes (ps = 0.48-0.12).

CONCLUSION

Cognitive decline associated with high BPV may be specifically accelerated among APOE ɛ4 carriers.

Visit-to-Visit Blood Pressure Variability and CSF Alzheimer Disease Biomarkers in Cognitively Unimpaired and Mildly Impaired Older Adults

BACKGROUND AND OBJECTIVES

Blood pressure variability is an emerging risk factor for cognitive decline and dementia, but mechanisms remain unclear. The current study examined whether visit-to-visit blood pressure variability is related to CSF Alzheimer disease biomarker levels over time and whether associations differed by APOE ε4 carrier status.

METHODS

In this retrospective analysis of a prospective cohort study, cognitively unimpaired or mildly impaired older adults from the Alzheimer's Disease Neuroimaging Initiative underwent 3 to 4 blood pressure measurements over a 12-month period and ≥1 lumbar puncture for evaluation of CSF phosphorylated tau, total tau, and β-amyloid levels at follow-up (6-108 months later). APOE ε4 carriers were defined as having ≥1 ε4 allele. Visit-to-visit blood pressure variability was determined over 12 months as variability independent of mean. Only CSF samples collected after the final blood pressure measurement were analyzed. Bayesian linear growth modeling investigated the role of blood pressure variability, APOE ε4, and the passage of time on CSF biomarker levels after controlling for several variables, including average blood pressure and baseline hypertension.

RESULTS

Four hundred sixty-six participants (mean 76.7 [SD 7.1] years of age) were included in the study. Elevated blood pressure variability was associated with increased CSF phosphorylated tau (β = 0.81 [95% CI 0.74, 0.97]), increased total tau (β = 0.98 [95% CI 0.71, 1.31]), and decreased β-amyloid levels (β = -1.52 [95% CI -3.55, -0.34]) at follow-up. APOE ε4 carriers with elevated blood pressure variability had the fastest increase in phosphorylated tau levels (β = 9.03 [95% CI 1.67, 16.36]). Blood pressure variability was not significantly related to total tau or β-amyloid levels over time according to APOE ε4 carrier status.

DISCUSSION

Older adults with elevated blood pressure variability exhibit increased CSF phosphorylated tau, increased total tau, and decreased β-amyloid over time, suggesting that blood pressure variability may correlate with alterations in Alzheimer disease biomarkers. Findings warrant further study of the relationship between blood pressure variability and the development of Alzheimer disease. APOE ε4 carrier status moderated relationships between blood pressure variability and CSF phosphorylated tau but not total tau or β-amyloid, consistent with other studies relating hemodynamic factors to tau changes.

Day-to-day blood pressure variability predicts poor outcomes following percutaneous coronary intervention: A retrospective study

BACKGROUND

For patients with cardiovascular disease, blood pressure variability (BPV), distinct from hypertension, is an important determinant of adverse cardiac events. Whether pre-operative BPV adversely affects outcomes after percutaneous coronary intervention (PCI) is to this point unclear.

AIM

To investigate the relationship between blood pressure variability and outcomes for patients post-PCI.

METHODS

Patients undergoing PCI in a single state in 2017 were studied (n = 647). Systolic and diastolic BPV, defined as both the largest change and standard deviation for the 3-60 mo prior to PCI was calculated and patients with more than ten blood pressure measurements in that time were included for analysis (n = 471). Adverse outcomes were identified up to a year following the procedure, including major adverse cardiac events (MACE), myocardial infarction, cerebrovascular accident, death, and all-cause hospitalization.

RESULTS

Visit-to-visit systolic BPV, as measured by both standard deviation and largest change, was higher in patients who had myocardial infarction, were readmitted, or died within one year following PCI. Systolic BPV, as measured by largest change or standard deviation, was higher in patients who had MACE, or readmissions (P < 0.05). Diastolic BPV, as measured by largest change, was higher in patients with MACE and readmissions (P < 0.05).

CONCLUSION

As BPV is easily measured and captured in the electronic medical record, these findings describe a novel method of identifying at-risk patients who undergo PCI. Aggressive risk modification for patients with elevated BPV and known coronary artery disease is indicated.

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.

Visit-to-visit blood pressure variability and risk of dementia in chronic kidney disease patients: why are blood pressure changes so important in cognitive functions?

Chronic kidney disease (CKD) is associated with cognitive functional impairment or dementia in addition to cardiovascular diseases. Aging of the population and the increasing prevalence of CKD in elderly patients are making dementia more prevalent. Blood pressure (BP) variability is an important risk factor for dementia. Although ample data link high BP variability with the risk of dementia in the general population, data on CKD patients are scarce. An observational cohort study conducted by Park et al., including 103 139 patients, demonstrated a strong association between higher visit-to-visit BP variability and increased risk of dementia in CKD patients. Both higher systolic and diastolic BP variabilities were associated with any type of dementia, including Alzheimer's and vascular dementia. Physicians must be aware of BP variability when evaluating CKD patients with hypertension.

Association between visit-to-visit blood pressure variability and risks of dementia in CKD patients: a nationwide observational cohort study

Background

The association between visit-to-visit blood pressure (BP) variability and dementia risk in chronic kidney disease (CKD) patients has rarely been studied.

Methods

In this retrospective observational study, individuals who received three or more general health screenings were identified in the nationwide database of Korea. Those with persistent non-dialysis-dependent CKD [estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² or dipstick albuminuria ≥1+] were included. The study exposure was systolic or diastolic BP variability, calculated as the variation independent of the mean and categorized into quartiles (Q4: the highest quartile; Q1: the lowest quartile). The risks of all-cause dementia, including Alzheimer's disease and vascular dementia, were analyzed by Cox regression adjusted for various clinical characteristics, including baseline BP and eGFR values.

Results

We included 103 139 CKD patients and identified 7574 (7%) dementia events, including 5911 (6%) Alzheimer's disease cases, 886 (1%) vascular dementia events and 777 (1%) cases categorized as other types of dementia. Higher systolic BP variability was significantly associated with higher risks of all-cause dementia {[Q4 versus Q1], hazard ratio [HR] 1.173 [95% confidence interval (CI) 1.102-1.249], P for trend < .001}. The results were also significant for the risk of Alzheimer's disease [HR 1.162 (95% CI 1.083-1.248), P < .001] and vascular dementia [HR 1.282 (95% CI 1.064-1.545), P = .039]. The results were similar when diastolic BP variability was the exposure, as high diastolic BP variability was significantly associated with higher risks of all-cause dementia [HR 1.191 (95% CI 1.117,1.270), P < .001].

Conclusions

Higher visit-to-visit BP variability is significantly associated with a higher risk of dementia in CKD patients.

Cardiovascular autonomic dysfunction is associated with executive dysfunction and poorer quality of life in progressive supranuclear palsy-Richardson's syndrome

BACKGROUND

Autonomic dysfunction in progressive supranuclear palsy (PSP) is not uncommon but is easily neglected.

OBJECTIVE

We evaluated blood pressure (BP) profiles in PSP patients and aimed to determine the associations between BP variability and cognition and quality of life.

METHODS

Consecutive patients diagnosed with PSP were enrolled in this cross-sectional study. All patients underwent 24-hour ambulatory blood pressure monitoring, office blood pressure measurements, and comprehensive clinical assessments.

RESULTS

We enrolled 31 PSP patients. Ten (32.3%) patients presented with reverse dipping, 10 (32.3%) presented with reduced dipping, and 11 (35.5%) presented with normal dipping. Additionally, 19 (61.3%) patients had supine hypertension, and no patients had orthostatic hypotension. In the entire PSP cohort, the Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III (MDS-UPDRS III) score, Scales for Outcomes in Parkinson's Disease-Autonomic (SCOPA-AUT) score, and daytime systolic BP (SBP) standard deviation explained 61.5% (adjusted R²) of the variance in Parkinson's Disease Questionnaire-39 (PDQ-39) scores. In the PSP with Richardson's syndrome group, the daytime SBP coefficient of variation and Mini-Mental State Examination score accounted for 33.9% of the variance in Frontal Assessment Battery scores. The MDS-UPDRS III score, 24-hour SBP coefficient of variation, and SCOPA-AUT score explained 77.6% of the variance in PDQ-39 scores.

CONCLUSIONS

Greater BP variability was associated with executive dysfunction and poorer quality of life in patients with PSP. A high prevalence of abnormal dipping patterns indicated circadian disruption in patients with PSP.

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.

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.

The Insular Cortex, Alzheimer Disease Pathology, and Their Effects on Blood Pressure Variability

Recent findings indicate that the human cardiovascular system is regulated by a cortical network comprised of the insular cortex (Ic), anterior cingulate gyrus, and amygdala which is necessary for the regulation of the central autonomic network system. Alzheimer disease (AD) affects the Ic at a preclinical stage. The pathology of AD at the Ic is suggested to predispose the cardiovascular system to detrimental changes such as increased blood pressure variability (BPV). In this review article, we focus on the physiology of the Ic in the relationship between the central autonomic network and BPV. We provide a summary of the published evidence regarding the relationship between Ic damage and exaggerated BPV in the context of AD pathology.

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.

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.

Blood pressure variability is related to faster cognitive decline in ischemic stroke patients: PICASSO subanalysis

Blood pressure variability (BPV) is associated with higher cardiovascular morbidity risks; however, its association with cognitive decline remains unclear. We investigated whether higher BPV is associated with faster declines in cognitive function in ischemic stroke (IS) patients. Cognitive function was evaluated between April 2010 and August 2015 using the Mini-mental State Examination (MMSE) and Montreal Cognitive Assessment in 1,240 Korean PICASSO participants. Patients for whom baseline and follow-up cognitive test results and at least five valid BP readings were available were included. A restricted maximum likelihood–based Mixed Model for Repeated Measures was used to compare changes in cognitive function over time. Among a total of 746 participants (64.6 ± 10.8 years; 35.9% female). Baseline mean-MMSE score was 24.9 ± 4.7. The median number of BP readings was 11. During a mean follow-up of 2.6 years, mean baseline and last follow-up MMSE scores were 25.4 ± 4.8 vs. 27.8 ± 4.4 (the lowest BPV group) and 23.9 ± 5.2 vs. 23.2 ± 5.9 (the highest BPV group). After adjusting for multiple variables, higher BPV was independently associated with faster cognitive decline over time. However, no significant intergroup difference in cognitive changes associated with mean systolic BP was observed. Further research is needed to elucidate how BPV might affect cognitive function.

Visit-to-Visit Blood Pressure Variability Is Associated With Cognitive Decline and Incident Dementia: The S.AGES Cohort

To investigate the impact of visit-to-visit systolic blood pressure variability (BPV), diastolic BPV, mean arterial pressure variability, and pulse pressure variability on cognitive decline and incident dementia in noninstitutionalized patients aged ≥65 years. A total of 3319 subjects from the S.AGES (Sujets AGÉS-Aged Subjects) cohort underwent clinical examinations every 6 months during 3 years. Variability was evaluated using standard deviation (SD), coefficient of variation, average real variability, successive variation, variation independent of mean, and residual SD. Cognition was assessed using the Mini-Mental State Examination and dementia with the Diagnostic Statistical Manual of Mental Disorders. Linear mixed models and Cox proportional hazards models were used. Higher systolic BPV was associated with poorer cognition independently of baseline SBP: adjusted 1-SD increase of coefficient of variation: β (SE)=-0.12 (0.06), P=0.04. Similar results were observed for diastolic BPV and mean arterial pressure variability: β (SE)=-0.20 (0.06), P<0.001 for both. Higher pulse pressure variability was no longer associated with cognitive function after adjustment for age, except with residual SD (P=0.02). Among the 3319 subjects, 93 (2.8%) developed dementia. Higher systolic BPV was associated with greater dementia risk (adjusted 1-SD increase of coefficient of variation: hazard ratios=1.23 [95% CI, 1.01-1.50], P=0.04). Similar results were found for diastolic BPV and mean arterial pressure variability (P<0.01). Pulse pressure variability was not associated with dementia risk. Beyond hypertension, higher BPV is a major clinical predictor of cognitive impairment and dementia. Further studies are needed to assess whether controlling BP instability could be a promising interventional target in preserving cognition among older adults.

Effect of Visit-to-Visit Blood Pressure Variability on Cognitive and Functional Decline in Mild to Moderate Alzheimer's Disease

BACKGROUND

Visit-to-visit blood pressure (BP) variability (VVV) is increasingly recognized as a marker of cardiovascular risk. Although implicated in cognitive decline, few studies are currently available assessing its effects on established dementia.

OBJECTIVE

To investigate if VVV is associated with one-year rate of decline in measures of cognition and function in patients with mild to moderate Alzheimer's disease (AD) in the Doxycycline And Rifampicin for Alzheimer's Disease study.

METHODS

Patients were included if ≥3 BP readings were available (n = 392). VVV was defined using different approaches including the coefficient of variation (CV) in BP readings between visits. Outcomes included rates of decline in the Standardized Alzheimer's Disease Assessment Scale-Cognitive Subscale (SADAS-cog), Standardized MMSE, Clinical Dementia Rating Scale, the Quick Mild Cognitive Impairment screen and the Lawton-Brody activities of daily living (ADL) scale.

RESULTS

Half of the patients (196/392) had a ≥4-point decline in the SADAS-cog over one-year. Using this cut-off, there were no statistically significant associations between any measures of VVV, for systolic or diastolic BP, with and without adjustment for potential confounders including treatment allocation, history of hypertension and use of anti-hypertensive and cognitive enhancing medications. Multiple regression models examining the association between systolic BP CV by quartile and decline over one-year likewise showed no clinically significant effects, apart from a U-shaped pattern of ADL decline of borderline clinical significance.∥Conclusions: This observational study does not support recent research showing that VVV predicts cognitive decline in AD. Further studies are needed to clarify its effects on ADL in AD.

Blood Pressure Variability and the Risk of Dementia: A Nationwide Cohort Study

To investigate the association between visit-to-visit variability in blood pressure and the incidence of dementia and its subtypes in a general population, we conducted a population-based retrospective cohort study using the Korean National Health Insurance System database. We identified 7 844 814 subjects without a history of any dementia who underwent ≥3 health examinations from 2005 to 2012 in the Korean National Health Insurance System cohort. Blood pressure variability (BPV) was measured using the variability independent of the mean, coefficient of variation, and SD. During the median follow-up of 6.2 years, there were 200 574 cases of all-cause dementia (2.8%), 165 112 cases of Alzheimer's disease (2.1%), and 27 443 cases of vascular dementia (0.3%). There was a linear association between higher BPV and outcome measures. In the multivariable adjusted model, the hazard ratios and 95% CIs of all-cause dementia were 1.06 (1.04-1.07) for the highest quartile of variability independent of the mean of diastolic blood pressure only, 1.09 (1.08-1.11) for that of systolic blood pressure only, and 1.18 (1.16-1.19) for that of both systolic and diastolic blood pressure compared with subjects having no highest quartile for BPV. Consistent results were noted for Alzheimer's disease and vascular dementia using other indices of variability and in various sensitivity and subgroup analyses. BPV is an independent predictor for developing dementia and its subtypes. A dose-response relationship was noted between higher BPV and dementia incidence. Reducing BPV may be a target for preventing dementia in the general population.

Preoperative outpatient blood pressure variability predicts postoperative mortality, readmission and morbidity after surgery

BACKGROUND

Outpatient blood pressure variability (BPV) predicts hospitalization and death in non-surgical patients independently of hypertension. We hypothesized that preoperative BPV predicts postoperative outcomes.

METHODS

We assessed 22,233 veterans undergoing CABG, colectomy, hip replacement, pancreatectomy, carotid endarterectomy or AV-fistula with ≥10 outpatient BP's over three preoperative years. Calculating BPV as SD of systolic or diastolic BP, we used logistic regression considering demographics, comorbidities, and pre-admission cardiovascular medications to estimate odds ratios for 90-day mortality or readmission, MI, CVA, renal failure, and wound infection, choosing the lowest 5%ile of systolic/diastolic BPV for reference.

RESULTS

Covariate-adjusted ORs for adverse outcomes increased as BPV increased. For instance, the highest 5%ile of systolic BPV had covariate-adjusted ORs of 2.96 and 1.78 for 90-day mortality and readmission. Systolic and diastolic BPV trended together but affected outcomes independently.

CONCLUSIONS

Preoperative BPV predicts postoperative outcomes. BPV should be considered in individualized risk assessment and subgroup risk stratification.

Long-Term Blood Pressure Variability Across the Clinical and Biomarker Spectrum of Alzheimer's Disease

BACKGROUND

Elevated blood pressure is linked to cognitive impairment and Alzheimer's disease (AD) biomarker abnormality. However, blood pressure levels vary over time. Less is known about the role of long-term blood pressure variability in cognitive impairment and AD pathophysiology.

OBJECTIVE

Determine whether long-term blood pressure variability is elevated across the clinical and biomarker spectrum of AD.

METHODS

Alzheimer's Disease Neuroimaging Initiative participants (cognitively normal, mild cognitive impairment, AD [n = 1,421]) underwent baseline exam, including blood pressure measurement at 0, 6, and 12 months. A subset (n = 318) underwent baseline lumbar puncture to determine cerebrospinal fluid amyloid-β and phosphorylated tau levels. Clinical groups and biomarker-confirmed AD groups were compared on blood pressure variability over 12 months.

RESULTS

Systolic blood pressure variability was elevated in clinically diagnosed AD dementia (VIM: F2,1195 = 6.657, p = 0.001, η2 = 0.01) compared to cognitively normal participants (p = 0.001), and in mild cognitive impairment relative to cognitively normal participants (p = 0.01). Findings were maintained in biomarker-confirmed AD (VIM: F2,850 = 5.216, p = 0.006, η2 = 0.01), such that systolic blood pressure variability was elevated in biomarker-confirmed dementia due to AD relative to cognitively normal participants (p = 0.005) and in biomarker-confirmed mild cognitive impairment due to AD compared to cognitively normal participants (p = 0.04).

CONCLUSION

Long-term systolic blood pressure variability is elevated in cognitive impairment due to AD. Blood pressure variability may represent an understudied aspect of vascular dysfunction in AD with potential clinical implications.

Association Between Blood Pressure Variability and Cerebral Small-Vessel Disease: A Systematic Review and Meta-Analysis

Background

Research links blood pressure variability (BPV) with stroke; however, the association with cerebral small‐vessel disease (CSVD) remains unclear. As BPV and mean blood pressure are interrelated, it remains uncertain whether BPV adds additional information to understanding cerebrovascular morphological characteristics.

Methods and Results

A systematic review was performed from inception until March 3, 2019. Eligibility criteria included population, adults without stroke (<4 weeks); exposure, BPV quantified by any metric over any duration; comparison, (1) low versus high or mean BPV and (2) people with versus without CSVD; and outcomes, (1) CSVD as subcortical infarct, lacunae, white matter hyperintensities, cerebral microbleeds, or enlarged perivascular spaces; and (2) standardized mean difference in BPV. A total of 27 articles were meta‐analyzed, comprising 12 309 unique brain scans. A total of 31 odds ratios (ORs) were pooled, indicating that higher systolic BPV was associated with higher odds for CSVD (OR, 1.27; 95% CI, 1.14–1.42; I²=85%) independent of mean systolic pressure. Likewise, higher diastolic BPV was associated with higher odds for CSVD (OR, 1.30; 95% CI, 1.14–1.48; I²=53%) independent of mean diastolic pressure. There was no evidence of a pairwise interaction between systolic/diastolic and BPV/mean ORs (P=0.47), nor a difference between BPV versus mean pressure ORs (P=0.58). Fifty‐four standardized mean differences were pooled and provided similar results for pairwise interaction (P=0.38) and difference between standardized mean differences (P=0.70).

Conclusions

On the basis of the available studies, BPV was associated with CSVD independent of mean blood pressure. However, more high‐quality longitudinal data are required to elucidate whether BPV contributes unique variance to CSVD morphological characteristics.

Variation in blood pressure and long-term risk of dementia: A population-based cohort study

BACKGROUND

Variation in blood pressure may relate to dementia risk via autonomic disturbance or hemodynamic mechanisms, but the long-term associations are unclear. We aimed to determine whether blood pressure variation over a period of years, considering both magnitude and direction, is associated with the risk of dementia.

METHODS AND FINDINGS

In a prospective cohort study ongoing since 1989 in the Netherlands, 5,273 dementia-free participants (58.1% women; mean [SD] age, 67.6 [8.0] years) were included. As of 2016, 1,059 dementia cases occurred during a median follow-up of 14.6 years. Absolute variation in systolic blood pressure (SBP) was assessed as the absolute difference in SBP divided by the mean over two sequential visits every 4.2 (median) years, with the first quantile set as the reference level. The direction was the rise or fall in SBP, with the third quantile set as the reference level. We estimated the risk of dementia in relation to SBP variation measured at different time windows (i.e., at least 0, 5, 10, and 15 years) prior to dementia diagnosis, with adjustments for age, sex, education, apolipoprotein E (APOE) genotype, vascular risk factors, and history of cardiovascular disease. We repeated the above analysis for variation in diastolic blood pressure (DBP). A large SBP variation was associated with an increased dementia risk, which became more pronounced with longer intervals between the assessment of SBP variation and the diagnosis of dementia. The hazard ratio (HR) associated with large variation (the highest quintile) increased from 1.08 (95% confidence interval [CI] 0.88-1.34, P = 0.337) for risk within 5 years of SBP variation measurement to 3.13 (95% CI 2.05-4.77; P < 0.001) for risk after at least 15 years since the measurement of SBP variation. The increased long-term risk was associated with both large rises (HR for the highest quintile, 3.31 [95% CI 2.11-5.18], P < 0.001) and large falls in SBP (HR for the lowest quintile, 2.20 [95% CI 1.33-3.63], P = 0.002), whereas the higher short-term risk was only associated with large falls in SBP (HR, 1.21 [95% CI 1.00-1.48], P = 0.017). Similar findings were observed for variation in DBP. Despite our assessment of major confounders, potential residual confounding is possible, and the findings on blood pressure variability over periods of years may not be generalizable to variability over periods of days and other shorter periods.

CONCLUSIONS

Results of this study showed that a large blood pressure variation over a period of years was associated with an increased long-term risk of dementia. The association between blood pressure variation and dementia appears most pronounced when this variation occurred long before the diagnosis. An elevated long-term risk of dementia was observed with both a large rise and fall in blood pressure.

Blood Pressure Variability and Progression of Clinical Alzheimer Disease

Blood pressure variability (BPV) has been shown to have predictive value over blood pressure (BP) levels alone in stroke patients. We assessed whether BPV predicts cognitive and functional decline in Alzheimer disease, using data from a randomized trial (NILVAD [A European Multicentre Double-blind Placebo-controlled Phase III Trial of Nilvadipine in Mild to Moderate Alzheimer’s Disease]). Patients with mild-to-moderate Alzheimer disease were included if they had ≥3 office BP measurements available to determine visit-to-visit BPV. Day-to-day BPV was assessed using home BP measurements in a subsample. The variation independent of mean was used to calculate BPV. Outcomes were change in Alzheimer’s Disease Assessment Scale–cognitive subscale-12 and Disability Assessment for Dementia after 1 and 1.5 years. A total of 460 patients aged 72.1 (SD=8.1) years, with mean BP of 134.0/75.1 (10.9/6.3) mm Hg were included. After 1 year, patients in the highest quartile of BPV had deteriorated more on Alzheimer’s Disease Assessment Scale–cognitive subscale compared with patients in the lowest quartile (systolic: β, 2.24 [95% CI, 0.11–4.38], P =0.040; diastolic: β, 2.54 [95% CI, 0.33–4.75] P =0.024). This association was still present after 1.5 years (systolic: β, 2.86 [95% CI, 0.35–5.36], P =0.026; diastolic: β, 3.30 [95% CI, 0.67–5.93], P =0.014). There was no effect of visit-to-visit BPV on Disability Assessment for Dementia. Day-to-day BPV was available for 46 patients. Significant associations were observed between day-to-day BPV and deterioration on Alzheimer’s Disease Assessment Scale–cognitive subscale (systolic: P =0.036) and Disability Assessment for Dementia (systolic: P =0.020; diastolic: P =0.007) after 1 year, but not after 1.5 years. All associations were adjusted for potential confounders, including intervention group. In conclusion, this post hoc analysis indicates that higher visit-to-visit and day-to-day BPV might be associated with progression of Alzheimer disease. Targeting BPV may be a future target to slow decline in patients with Alzheimer disease.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02017340.

Visit-To-Visit Blood Pressure Variability and the Risk of Dementia in Older People

BACKGROUND

High visit-to-visit variability (VVV) in blood pressure (BP) is associated with cerebrovascular lesions on neuroimaging.

OBJECTIVE

Our primary objective was to investigate whether VVV is associated with incident all-cause dementia. As a secondary objective, we studied the association of VVV with cognitive decline and cardiovascular disease (CVD).

METHODS

We included community-dwelling people (age 70-78 year) from the 'Prevention of Dementia by Intensive Vascular Care' (preDIVA) trial with three to five 2-yearly BP measurements during 6-8 years follow-up. VVV was defined using coefficient of variation (CV; SD/mean×100). Cognitive decline was assessed using the Mini-Mental State Examination (MMSE). Incident CVD was defined as myocardial infarction or stroke. We used a Cox proportional hazard regression and mixed-effects model adjusted for sociodemographic factors and cardiovascular risk factors.

RESULTS

In 2,305 participants (aged 74.2±2.5), mean systolic BP over all available visits was 150.1 mmHg (SD 13.6), yielding a CV of 9.0. After 6.4 years (SD 0.8) follow-up, 110 (4.8%) participants developed dementia and 140 (6.1%) CVD. Higher VVV was not associated with increased risk of dementia (hazard ratio [HR] 1.00 per point CV increase; 95% confidence interval [CI] 0.96-1.05), although the highest quartile of VVV was associated with stronger decline in MMSE (β -0.09, 95% CI -0.17 to -0.01). Higher VVV was associated with incident CVD (HR 1.07; 95% CI 1.04-1.11).

CONCLUSION

In our study among older people, high VVV is not associated with incident all-cause dementia. It is associated with decline in MMSE and incident CVD.

The association between blood pressure variability (BPV) with dementia and cognitive function: a systematic review and meta-analysis protocol

BACKGROUND

A body of empirical work demonstrates that wide fluctuations in a person's blood pressure across consecutive measures, known as blood pressure variability (BPV), hold prognostic value to predict stroke and transient ischemic attack. However, the magnitude of association between BPV and other neurological outcomes remains less clear. This systematic review aims to pool together data regarding BPV with respect to incident dementia, cognitive impairment, and cognitive function.

METHODS

Electronic databases (MEDLINE, EMBASE, and SCOPUS) will be searched for the key words blood pressure variability and outcomes of dementia, cognitive impairment, and cognitive function. Authors and reference lists of included studies will also be contacted to identify additional published and unpublished studies. Eligibility criteria are as follows: population-adult humans (over 18 years but with no upper age limit) without dementia at baseline, with or without elevated blood pressure, or from hypertensive populations (systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg or use of antihypertensive drug for hypertension) and from primary care, community cohort, electronic database registry, or randomized controlled trial (RCT); exposure-any metric of BPV (systolic, diastolic or both) over any duration; comparison-persons without dementia who do not have elevated BPV; and outcome-dementia, cognitive impairment, cognitive function at follow-up from standardized neurological assessment, or cognitive testing. Article screening will be undertaken by two independent reviewers with disagreements resolved through discussion. Data extraction will include original data specified as hazard ratios, odds ratios, correlations, regression coefficients, and original cell data if available. Risk of bias assessment will be undertaken by two independent reviewers. Meta-analytic methods will be used to synthesize the data collected relating to the neurological outcomes with Comprehensive Meta-Analysis Version 2.0 (Biostat Inc., Engelwood, NJ).

DISCUSSION

This systematic review aims to clarify whether BPV is associated with elevated risk for dementia, cognitive impairment, and cognitive function. An evaluation of the etiological links between BPV with incident dementia might inform evidence-based clinical practice and policy concerning blood pressure measurement and hypertension management. The review will identify sources of heterogeneity and may inform decisions on whether it is feasible and desirable to proceed with an individual participant data meta-analysis.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017081977.

Visit-to-Visit Variability of Blood Pressure Is Associated With Hospitalization and Mortality in an Unselected Adult Population

BACKGROUND

Blood pressure variability (BPV) has been associated with poor health outcomes in high-risk patients, but its association with more general populations is poorly understood.

METHODS

We analyzed outcomes from 240,622 otherwise unselected patients who had 10 or more outpatient blood pressure readings recorded over a 3-year period and were aged from 20 to 100 years.

RESULTS

Whether calculated as SD, average change, or greatest change and systolic or diastolic blood pressure, we found that higher outpatient BPV was associated with subsequent hospitalization and mortality. Systolic pressure average change exceeding 10-12 mm Hg or diastolic exceeding 8 mm Hg significantly increased risk of hospitalization and death (odds ratios [ORs] from 2.0 to 4.5). Variability in the highest decile increased risks even more dramatically, with propensity-matched ORs from 4.4 to 42. A systolic change exceeding 35 mm Hg increased the relative risk of death 4.5-fold. Similarly, a diastolic change greater than 23-24 mm Hg almost tripled the risks of hospitalization and death. Neither stratification for hypertension nor propensity matching for risk factors within the database affected these associations.

CONCLUSIONS

Systolic and diastolic variabilities were each associated with subsequent adverse outcomes. Physicians should pay special attention to patients with swings in blood pressure between clinic visits. Electronic medical records should flag such variability.

Dynamic Regulation of Cerebral Blood Flow in Patients With Alzheimer Disease

Cerebral autoregulation and baroreflex sensitivity are key mechanisms that maintain cerebral blood flow. This study assessed whether these control mechanisms are affected in patients with dementia and mild cognitive impairment due to Alzheimer disease, as this would increase the risks of antihypertensive treatment. We studied 53 patients with dementia (73.1 years [95% confidence interval (CI), 71.4–74.8]), 37 patients with mild cognitive impairment (69.2 years [95% CI, 66.4–72.0]), and 47 controls (69.4 years [95% CI, 68.3–70.5]). Beat-to-beat blood pressure (photoplethysmography), heart rate, and cerebral blood flow velocity (transcranial Doppler) were measured during 5-minute rest (sitting) and 5 minutes of orthostatic challenges, using repeated sit-to-stand maneuvers. Cerebral autoregulation was assessed using transfer function analysis and the autoregulatory index. Baroreflex sensitivity was estimated with transfer function analysis and by calculating the heart rate response to blood pressure changes during the orthostatic challenges. Dementia patients had the lowest cerebral blood flow velocity ( P =0.004). During rest, neither transfer function analysis nor the autoregulatory index indicated impairments in cerebral autoregulation. During the orthostatic challenges, higher autoregulatory index ( P =0.011) and lower transfer function gain ( P =0.017), indicating better cerebral autoregulation, were found in dementia (4.56 arb. unit [95% CI, 4.14–4.97]; 0.59 cm/s per mm Hg [95% CI, 0.51–0.66]) and mild cognitive impairment (4.59 arb. unit [95% CI, 4.04–5.13]; 0.51 cm/s per mm Hg [95% CI, 0.44–0.59]) compared with controls (3.71 arb. unit [95% CI, 3.35–4.07]; 0.67 cm/s per mm Hg [95% CI, 0.59–0.74]). Baroreflex sensitivity measures did not differ between groups. In conclusion, the key mechanisms to control blood pressure and cerebral blood flow are not reduced in 2 stages of Alzheimer disease compared with controls, both in rest and during orthostatic changes that reflect daily life challenges.

Visit-to-visit variability in blood pressure and Alzheimer's disease

Alzheimer's disease is the most common type of dementia and one of the leading sources of disability and dependency in the elderly. Given the limited treatment options, understanding the role of modifiable risk factors implied in the disease pathogenesis is a worthwhile endeavor to limit its global burden. Recently, the variability of blood pressure has been suggested to be a significant determinant of brain alterations and a potential therapeutic target. The aim of this article is to review the clinical evidence on the association between visit-to-visit blood pressure variability and Alzheimer's disease, highlight the underlying mechanisms, and suggest future implications.