Contributions of Cerebral Blood Flow to Associations Between Blood Pressure Levels and Cognition: The Age, Gene/Environment Susceptibility-Reykjavik Study

Longitudinal alterations in cerebral perfusion following a season of adolescent contact sport participation compared to non-contact athletes

BACKGROUND

Cerebral blood flow (CBF) change, a non-invasive marker of head injury, has yet to be thoroughly investigated as a potential consequence of repetitive head impacts (RHI) via contact sport participation in youth athletes. We examined pre-to post-season differences in relative CBF (rCBF), arterial transit time (ATT), and neurocognition between adolescent contact sport (CS; 79.4% of which were football players) and non-contact sport (NCS) athletes.

METHODS

Adolescent athletes (N = 57; age = 14.70 ± 1.97) completed pre- and post-season clinical assessments and neuroimaging. Brain perfusion was evaluated using an advanced 3D pseudo-continuous ASL sequence with Hadamard encoded multiple post-labeling delays. Mixed-effect models tested group-by-time interactions for rCBF, ATT, and neurocognition.

RESULTS

A significant group-by-time interaction was observed for rCBF in a cluster consisting primarily of frontal and parietal lobe regions, with regional rCBF increasing in CS and decreasing among NCS athletes. No significant interaction was observed for ATT. A significant group-by-time interaction was observed for verbal memory and visual motor speed, with NCS athletes improving and CS athletes exhibiting lower performance from pre-to post-season in comparison.

CONCLUSIONS

Alterations in rCBF and variability in cognition, not purported neurovasculature changes (measured by ATT), were observed following one season of CS participation. Further study surrounding the clinical meaningfulness of these findings, as they related to adverse long-term outcomes, is needed.

Dietary nitrate, aging and brain health: the latest evidence

PURPOSE OF REVIEW

With an increasing population age, cognitive decline and age-associated neurodegenerative diseases are becoming increasingly prevalent and burdensome in society. Dietary supplementation with inorganic nitrate, which serves as a nitric oxide precursor, has been suggested as a potential nutritional strategy to improve brain health in older adults. In this review, we discuss recent findings in this area.

RECENT FINDINGS

A number of studies have emerged in the past 12-18 months exploring the effects of dietary nitrate supplementation on cognitive function, with typically (although not exclusively) null findings emerging. This research is characterized by small, acute/short-term studies, although observational studies and longer-duration randomised controlled trials are beginning to emerge. From the limited research reporting benefits of nitrate supplementation on cognitive function, one important discovery has been the identification of a potential pathway through which nitrate could impact cognitive health, involving modulation of the oral microbiome, which warrants further investigation.

SUMMARY

Despite some promising early findings, there is currently insufficient evidence to recommend increased dietary nitrate intake for the purpose of improving brain health. However, longer-term, larger-scale trials in potentially responsive groups are warranted to provide definitive evidence in this area.

Cumulative effect of simvastatin, L-arginine, and tetrahydrobiopterin on cerebral blood flow and cognitive function in Alzheimer's disease

BACKGROUND AND OBJECTIVES

Vascular disease is a known risk factor for Alzheimer's disease (AD). Endothelial dysfunction has been linked to reduced cerebral blood flow. Endothelial nitric oxide synthase pathway (eNOS) upregulation is known to support endothelial health. This single-center, proof-of-concept study tested whether the use of three medications known to augment the eNOS pathway activity improves cognition and cerebral blood flow (CBF).

METHODS

Subjects with mild AD or mild cognitive impairment (MCI) were sequentially treated with the HMG-CoA reductase synthesis inhibitor simvastatin (weeks 0-16), L-arginine (weeks 4-16), and tetrahydrobiopterin (weeks 8-16). The primary outcome of interest was the change in CBF as measured by MRI from baseline to week 16. Secondary outcomes included standard assessments of cognition.

RESULTS

A total of 11 subjects were deemed eligible and enrolled. One subject withdrew from the study after enrollment, leaving 10 subjects for data analysis. There was a significant increase in CBF from baseline to week 8 by ~13% in the limbic and ~15% in the cerebral cortex. Secondary outcomes indicated a modest but significant increase in the MMSE from baseline (24.2±3.2) to week 16 (26.0±2.7). Exploratory analysis indicated that subjects with cognitive improvement (reduction of the ADAS-cog 13) had a significant increase in their respective limbic and cortical CBF.

CONCLUSIONS

Treatment of mild AD/MCI subjects with medications shown to augment the eNOS pathway was well tolerated and associated with modestly increased cerebral blood flow and cognitive improvement.

TRIAL REGISTRATION

This study is registered in https://www.

CLINICALTRIALS

gov ; registration identifier: NCT01439555; date of registration submitted to registry: 09/23/2011; date of first subject enrollment: 11/2011.

Excess pressure but not pulse wave velocity is associated with cognitive function impairment: a community-based study

BACKGROUND

Carotid-femoral pulse wave velocity (cf-PWV), an index of mainly distal aortic stiffness, has been inconsistently associated with cognitive function. Excess pressure, derived from the arterial reservoir-excess pressure analysis, may integrate the pulsatile load of the proximal aorta. The present study examined whether increased excess pressure is associated with cognitive function impairment in community adults.

METHODS

A total of 992 community participants (69.5% females; mean age: 67.3 years; education 13.6 years) without cerebrovascular disease or dementia received the Montreal Cognitive Assessment (MoCA) to evaluate global cognition. Arterial reservoir and excess pressure, arterial stiffness, and wave reflections were assessed, using carotid tonometry and aortic Doppler flowmetry.

RESULTS

Excess pressure integral (XSPI), percentage XSPI, cf-PWV, characteristic impedance (Zc), and forward and backward pressure amplitude (Pf, Pb, respectively) were significantly higher in 197 participants (19.9%) with a low MoCA score (<26 or <25, depending on level of education). In multivariable analyses, XSPI (standardized odds ratio, 95% confidence interval, 1.30, 1.06-1.59), and percentage XSPI (1.27, 1.06-1.52) but not cf-PWV (1.04, 0.85-1.26) were significantly associated with a low MoCA. Further analysis revealed that Pf and Zc were the major determinants of XSPI (partial R2: Pf = 0.656, Zc = 0.467) and percentage XSPI (Pf = 0.459, Zc = 0.371). In contrast, age, instead of Pf and Zc, was the major determinant of cf-PWV (partial R2: age = 0.187).

CONCLUSIONS

Excess pressure (XSPI/percentage XSPI), mainly determined by the pulsatile hemodynamics of the proximal aorta, was significantly associated with cognitive function impairment in middle-aged and elderly community adults.

Disentangling the varying associations between systolic blood pressure and health outcomes in the very old: an individual patient data meta-analysis

OBJECTIVES

While randomized controlled trials have proven the benefits of blood pressure (BP) lowering in participating octogenarians, population-based observational studies suggest an association between low systolic blood pressure (SBP) and faster overall decline. This study investigates the effects of BP-lowering treatment, a history of cardiovascular diseases (CVD), and cognitive and physical fitness on the associations between SBP and health outcomes in the very old.

METHODS

Five cohorts from the Towards Understanding Longitudinal International older People Studies (TULIPS) consortium were included in a two-step individual participant data meta-analysis (IPDMA). We pooled hazard ratios (HR) from Cox proportional-hazards models for 5-year mortality and estimates of linear mixed models for change in cognitive and functional decline. Models were stratified by BP-lowering treatment, history of CVD, Mini-Mental State Examination scores, grip strength (GS) and body mass index (BMI).

RESULTS

Of all 2480 participants (59.9% females, median 85 years), median baseline SBP was 149 mmHg, 64.3% used BP-lowering drugs and 47.3% had a history of CVD. Overall, higher SBP was associated with lower all-cause mortality (pooled HR 0.91 [95% confidence interval 0.88-0.95] per 10 mmHg). Associations remained irrespective of BP-lowering treatment, history of CVD and BMI, but were absent in octogenarians with above-median MMSE and GS. In pooled cohorts, SBP was not associated with cognitive and functional decline.

CONCLUSION

While in the very old with low cognitive or physical fitness a higher SBP was associated with a lower all-cause mortality, this association was not evident in fit octogenarians. SBP was not consistently associated with cognitive and functional decline.

Exploration of cerebral hemodynamic pathways through which large artery function affects neurovascular coupling in young women

Background

The interactions between large artery function and neurovascular coupling (NVC) are emerging as important contributors to cognitive health. Women are disproportionally affected by Alzheimer's disease and related dementia later in life. Understanding large artery correlates of NVC in young women may help with preservation of cognitive health with advancing age.

Purpose

To explore the association between large artery function, NVC and cognitive performance in young women.

Methods

Vascular measurements were made in 61 women (21 ± 4 yrs) at rest and during a cognitive challenge (Stroop task). Transcranial Doppler was used to measure left middle cerebral artery (MCA) maximum velocity (Vmax), mean velocity (Vmean), and pulsatility index (PI). NVC was determined as MCA blood velocity reactivity to the Stroop task. Large artery function was determined using carotid-femoral pulse wave velocity (cfPWV) as a proxy measure of aortic stiffness and carotid ultrasound-derived measures of compliance and reactivity (diameter change to the Stroop task). Cognitive function was assessed separately using a computerized neurocognitive battery that included appraisal of response speed, executive function, information processing efficiency, memory, attention/concentration, and impulsivity.

Results

MCA Vmax reactivity was positively associated with executive function (β = 0.26, 95% CI 0.01–0.10); MCA Vmean reactivity was negatively associated with response speed (β = −0.33, 95% CI −0.19 to −0.02) and positively with memory score (β = 0.28, 95% CI 0.01–0.19). MCA PI reactivity was negatively associated with attention performance (β = −0.29, 95% CI −14.9 to −1.0). Path analyses identified significant paths (p &lt; 0.05) between carotid compliance and carotid diameter reactivity to select domains of cognitive function through MCA reactivity.

Conclusions

NVC was associated with cognitive function in young women. Carotid artery function assessed as carotid compliance and carotid reactivity may contribute to optimal NVC in young women through increased blood flow delivery and reduced blood flow pulsatility.

Association between blood pressure control status, visit-to-visit blood pressure variability, and cognitive function in elderly Chinese: A nationwide study

Background

Cognitive function is a concern among the elderly, which is related to the quality of life, life expectancy, and economic burdens. The relationship between blood pressure (BP) control status, visit-to-visit BP variability, and cognitive function remains controversial.

Methods

We aimed to explore the association between BP control status at baseline, visit-to-visit BP variability, and cognitive function. This study included 3,511 elderlies in the China Health and Retirement Longitudinal Study, covering four waves for 7-year follow-up (baseline 2011, 2013, 2015, and 2018). BP was measured in Wave 2011, 2013, and 2015. Cognitive function was measured by Mini-Mental State Exam in Wave 2018. Participants were divided into two groups: mid-old group for reflecting midlife BP and cognition (45–59 years at baseline but aged 60 or over in Wave 2018), and old-old group for reflecting late-life BP and cognition (aged 60 or over at baseline). We use univariate analysis and general linear model to analyze.

Results

Late-life BP showed stronger associations with cognitive function than midlife BP. As to late-life BP control status, controlled hypertension group get higher cognitive score than uncontrolled hypertension group in language (adjusted β = −0.34, 95%CI −0.68 to 0.00), and untreated hypertension group in orientation (adjusted β = −0.41, 95%CI −0.72 to −0.11), language (adjusted β = −0.35, 95%CI −0.67 to −0.04), and total (adjusted β = −0.99, 95%CI −1.85 to −0.12). Regarding visit-to-visit BP variability, midlife visit-to-visit systolic blood pressure (SBP) variability was associated with language (adjusted β = −3.70, 95% CI −5.83 to −1.57), while late-life visit-to-visit SBP variability was associated with orientation (adjusted β = −2.99, 95% CI −4.84 to −1.14), recall (adjusted β = −1.69, 95% CI −2.89 to −0.48), language (adjusted β = −2.26, 95% CI −4.13 to −0.38), and total (adjusted β = −9.50, 95% CI −14.71 to −4.28); Midlife diastolic blood pressure (DBP) variability and pulse pressure (PP) variability showed a significant relationship with language (adjusted β = 3.25, 95% CI −1.31 to −5.19) and calculation (adjusted β = −0.26, 95% CI −0.47 to −0.04), respectively. No significant correlation was found between midlife BP control status, late-life visit-to-visit DBP variability, late-life visit-to-visit PP variability, and cognitive score. There was no significant correlation between BP and memory.

Conclusions

BP control status and visit-to-visit BP variability were significantly related to cognitive function among the Chinese elderly. Receiving effective late-life antihypertensive treatment and keeping SBP stable might contribute to prevent the development of cognitive impairment and dementia, especially for orientation and language function.

Short cognitive screening in elderlies as a part of advanced pharmaceutical care in Slovak community pharmacies - The pilot study KOGNIMET-SK

The aim of this study is to evaluate the implementation of a simple, easy-to-use cognitive screening test in the pharmaceutical care of elderly patients (aged 60 years and over) in community pharmacies and to test whether cognitive decline is associated with metabolic syndrome (MetS).

Current research has reported the increasing prevalence of MetS with age and indicated a link between cardiovascular risk factors and impairment of cognitive functions. We hypothesized that the short cognitive test realised in pharmaceutical care in community pharmacies could help identify risk groups of patients with potential cognitive decline. Because of the increasing pressure on primary care, collaboration between community pharmacists and general practitioners is essential, especially in preventive programmes and regarding chronically ill patients.

The study included 222 elderly patients aged 60 years and over reached between February 2018 and February 2019 in 16 community pharmacies in Slovakia. Criteria for the classification of MetS were used, following the International Diabetes Federation Worldwide Definition of MetS (2005) for European populations. Cognitive performance was evaluated using the Slovak version of the Montreal Cognitive Assessment. The scale range of the MoCA test is 0–30 points, and the cut-off for cognitive impairment is ≤ 24 points.

Our outcomes show that the presence of metabolic syndrome only slightly contributes to the impairment of cognitive functions of patients receiving routine pharmaceutical care in community pharmacies. Cognitive assessment might be an important tool for identifying risk groups of patients that would benefit from a specific approach within the framework of pharmaceutical care.

Therapeutic Potential of Remote Ischemic Conditioning in Vascular Cognitive Impairment

Vascular cognitive impairment (VCI) is a heterogeneous disease caused by a variety of cerebrovascular diseases. Patients with VCI often present with slower cognitive processing speed and poor executive function, which affects their independence in daily life, thus increasing social burden. Remote ischemic conditioning (RIC) is a non-invasive and efficient intervention that triggers endogenous protective mechanisms to generate neuroprotection. Over the past decades, evidence from basic and clinical research has shown that RIC is promising for the treatment of VCI. To further our understanding of RIC and improve the management of VCI, we summarize the evidence on the therapeutic potential of RIC in relation to the risk factors and pathobiologies of VCI, including reducing the risk of recurrent stroke, decreasing high blood pressure, improving cerebral blood flow, restoring white matter integrity, protecting the neurovascular unit, attenuating oxidative stress, and inhibiting the inflammatory response.