Vascular disease and cognitive impairment

Reduced levels of angiogenesis biomarkers predict increased symptom severity in Chinese Americans with Alzheimer's disease with demographic-specific effect

Alzheimer's disease (AD) symptomatology, while classically studied through the lens of amyloid-β and tau burden, is likely also influenced by multiple-interacting co-pathologies like vascular disease and dysmetabolism. These co-pathologies, especially vascular disease, occur disparately in the Chinese-American population and are often treatable via therapeutics and lifestyle modifications. Given this, we explored whether plasma biomarkers, including an array of vascular-related proteins, associate with cognition in a cohort of 34 Chinese Americans clinically diagnosed as cognitively normal, with mild cognitive impairment, or with AD. We found that a composite score of plasma angiogenesis biomarkers (MMP-1, bFGF, VEGF, and VEGF-C) were positively associated with total Mini Mental State Examination scores (p = 0.045) as well as memory performance (p = 0.006), and that this relationship was most pronounced in AD (biomarker composite score within AD vs MMSE & memory, both p < 0.001). To explore whether these findings were specific to the Chinese-American population, we repeated the above analyses in 73 demographically matched non-Hispanic White American participants and found no significant associations between angiogenesis biomarkers and MMSE or memory, highlighting the potential relevance of vascular dysregulation in Chinese Americans at risk for AD.

Dual burden of sarcopenia and impaired oral status on activities of daily living, cognition and swallowing outcomes in post-stroke patients

BACKGROUND AND AIMS

Sarcopenia and poor oral health are common in older patients and are associated with negative outcomes. However, evidence of their combined impact on post-stroke rehabilitation outcomes is limited. This study aimed to investigate the combined impact of sarcopenia and impaired oral health on activities of daily living (ADL), cognition, and swallowing outcomes in post-stroke patients.

METHODS

A retrospective cohort study was conducted using 1,012 post-stroke patients (median age 75.6 years; 54.1 % men). Sarcopenia was diagnosed using the Asian Working Group for Sarcopenia 2019 criteria. Poor oral health was assessed using the Revised Oral Assessment Guide (ROAG) with a score ≥13 indicating impaired oral status. Functional outcomes were measured using the Functional Independence Measure (FIM) for ADL and cognition, and the Food Intake Level Scale (FILS) for swallowing status.

RESULTS

The prevalence of sarcopenia was 45.6 % (492/1,080), impaired oral health was 27.5 % (297/1,080), and the coexistence of both conditions was 12.0 % (130/1,080). The coexistence of sarcopenia and impaired oral health was associated with poorer outcomes compared to either condition alone. After adjusting for confounders, the combination of sarcopenia and impaired oral status showed the strongest negative impact on FIM-motor (B=-8.666, 95 % CI -11.484 to -5.847), FIM-cognition (B=-1.122, 95 % CI -1.987 to -0.256), and FILS (B=-0.785, 95 % CI -1.055 to -0.514) scores at discharge.

CONCLUSION

The dual burden of sarcopenia and impaired oral health significantly impacts functional recovery in post-stroke patients. Comprehensive assessments and interventions targeting both conditions may optimize rehabilitation outcomes in this population.

Sex Differences in the Association Between Vascular Risk Factors and Cognitive Decline: A UK Biobank Study

Background

Age-related cognitive decline is accelerated by vascular risk factors for cerebral small vessel disease. However, the association of vascular risk factors with cerebral small vessel disease contributing to the sex differences in cognitive decline remains unclear.

Objectives

The purpose of this study was to evaluate sex differences in cognitive decline and the association between vascular risk factors and cognitive decline by sex.

Methods

We used data from the UK Biobank (>55 years of age; n = 19,067) to assess cognitive tests (executive function, processing speed, and memory) while adjusting for baseline measurements to examine how vascular risk factors affect cognition. A univariate regression analysis was used to assess sex differences at the first time point (2014). A repeated measure analysis with a mixed effect model was used to determine cognitive decline (between 2014 and 2019). Any significant interaction between vascular risk factors and sex was investigated.

Results

Females had lower scores in all 3 domains at the first cognitive tests (2014). We found a significant sex-by-time interaction over a 5-year period in matrix pattern completion (P = 0.03). After adjusting for vascular risk factors, this interaction was reduced (P = 0.08). High low-density lipoprotein, low education, and high blood pressure had a greater effect on the rate of cognitive decline in the executive function for females compared to males for the sex∗vascular risk factor interaction (P < 0.05).

Conclusions

The rate of cognitive decline did not differ significantly between males and females. However, the impact of several vascular risk factors on cognitive decline was greater in females than in males.

Reduced basal macrovascular and microvascular cerebral blood flow in young adults with metabolic syndrome: potential mechanisms

Ninety-million Americans suffer metabolic syndrome (MetSyn), increasing the risk of diabetes and poor brain outcomes, including neuropathology linked to lower cerebral blood flow (CBF), predominantly in anterior regions. We tested the hypothesis that total and regional CBF is lower in MetSyn more so in the anterior brain and explored three potential mechanisms. Thirty-four controls (25 ± 5 yr) and 19 MetSyn (30 ± 9 yr), with no history of cardiovascular disease/medications, underwent four-dimensional flow magnetic resonance imaging (MRI) to quantify macrovascular CBF, whereas arterial spin labeling quantified brain perfusion in a subset (n = 38/53). Contributions of cyclooxygenase (COX; n = 14), nitric oxide synthase (NOS, n = 17), or endothelin receptor A signaling (n = 13) were tested with indomethacin, NG-monomethyl-L-arginine (L-NMMA), and Ambrisentan, respectively. Total CBF was 20 ± 16% lower in MetSyn (725 ± 116 vs. 582 ± 119 mL/min, P < 0.001). Anterior and posterior brain regions were 17 ± 18% and 30 ± 24% lower in MetSyn; reductions were not different between regions (P = 0.112). Global perfusion was 16 ± 14% lower in MetSyn (44 ± 7 vs. 36 ± 5 mL/100 g/min, P = 0.002) and regionally in frontal, occipital, parietal, and temporal lobes (range 15-22%). The decrease in CBF with L-NMMA (P = 0.004) was not different between groups (P = 0.244, n = 14, 3), and Ambrisentan had no effect on either group (P = 0.165, n = 9, 4). Interestingly, indomethacin reduced CBF more in Controls in the anterior brain (P = 0.041), but CBF decrease in posterior was not different between groups (P = 0.151, n = 8, 6). These data indicate that adults with MetSyn exhibit substantially reduced brain perfusion without regional differences. Moreover, this reduction is not due to loss of NOS or gain of ET-1 signaling but rather a loss of COX vasodilation.NEW & NOTEWORTHY We tested the impact of insulin resistance (IR) on resting cerebral blood flow (CBF) in adults with metabolic syndrome (MetSyn). Using MRI and research pharmaceuticals to study the role of NOS, ET-1, or COX signaling, we found that adults with MetSyn exhibit substantially lower CBF that is not explained by changes in NOS or ET-1 signaling. Interestingly, adults with MetSyn show a loss of COX-mediated vasodilation in the anterior but not posterior circulation.

Capsaicin: A Potential Treatment to Improve Cerebrovascular Function and Cognition in Obesity and Ageing

Impaired cognition is the primary symptom of dementia, which can lead to functional disability and reduced quality of life among an increasingly ageing population. Ageing is associated with increased oxidative stress, chronic low-grade systemic inflammation, and endothelial dysfunction, which reduces cerebrovascular function leading to cognitive decline. Chronic low-grade systemic inflammatory conditions, such as obesity, exacerbate this decline beyond normal ageing and predispose individuals to neurodegenerative diseases, such as dementia. Capsaicin, the major pungent molecule of chilli, has recently demonstrated improvements in cognition in animal models via activation of the transient receptor potential vanilloid channel 1 (TRPV1). Capsaicin-induced TRPV1 activation reduces adiposity, chronic low-grade systemic inflammation, and oxidative stress, as well as improves endothelial function, all of which are associated with cerebrovascular function and cognition. This review examines the current literature on capsaicin and Capsimax, a capsaicin supplement associated with reduced gastrointestinal irritation compared to capsaicin. Acute and chronic capsaicin treatment can improve cognition in animals. However, studies adequately assessing the effects of capsaicin on cerebrovascular function, and cognition in humans do not exist. Capsimax may be a potentially safe therapeutic intervention for future clinical trials testing the effects of capsaicin on cerebrovascular function and cognition.

Incremental Doses of Nitrate-Rich Beetroot Juice Do Not Modify Cognitive Function and Cerebral Blood Flow in Overweight and Obese Older Adults: A 13-Week Pilot Randomised Clinical Trial

Nitrate-rich food increases nitric oxide (NO) production and may have beneficial effects on vascular, metabolic, and brain function. This pilot study tested the effects of prolonged consumption of a range of doses of dietary nitrate (NO₃^-), provided as beetroot juice, on cognitive function and cerebral blood flow (CBF) in overweight and obese older participants. The study had a 13-week single-blind, randomised, parallel design, and 62 overweight and obese older participants (aged 60 to 75 years) received the following interventions: (1) high NO₃^- (2 × 70 mL beetroot juice/day) (2) medium NO₃^- (70 mL beetroot juice/day), (3) low NO₃^- (70 mL beetroot juice on alternate days), or (4) placebo (70 mL of NO₃^--depleted beetroot juice on alternate days). Cognitive functions were assessed using the Computerised Mental Performance Assessment System (COMPASS) assessment battery. CBF, monitored by concentration changes in oxygenated and deoxygenated haemoglobin, was assessed in the frontal cortex using near-infrared spectroscopy. The findings of this pilot study showed that cognitive function and CBF were not affected by supplementation with NO₃^--rich beetroot juice for 13 weeks, irrespective of the NO₃^- dose administered. These findings require confirmation in larger studies using more sophisticated imaging methods (i.e., MRI) to determine whether prolonged dietary NO₃^- supplementation influences brain function in older overweight people.

Nitric oxide synthase inhibition in healthy adults reduces regional and total cerebral macrovascular blood flow and microvascular perfusion

The importance of nitric oxide (NO) in regulating cerebral blood flow (CBF) remains unresolved, due in part to methodological approaches, which lack a comprehensive assessment of both global and regional effects. Importantly, NO synthase (NOS) expression and activity appear greater in some anterior brain regions, suggesting region-specific NOS influence on CBF. We hypothesized that NO contributes to basal CBF in healthy adults, in a regionally distinct pattern that predominates in the anterior circulation. Fourteen healthy adults (7 females; 24 ± 5 years) underwent two magnetic resonance imaging (MRI) study visits with saline (placebo) or the NOS inhibitor, L-NMMA, administered in a randomized, single-blind approach. 4D flow MRI quantified total and regional macrovascular CBF, whereas arterial spin labelling (ASL) MRI quantified total and regional microvascular perfusion. L-NMMA (or volume-matched saline) was infused intravenously for 5 min prior to imaging. L-NMMA reduced CBF (L-NMMA: 722 ± 100 vs. placebo: 771 ± 121 ml/min, P = 0.01) with similar relative reductions (5-7%) in anterior and posterior cerebral circulations, due in part to the reduced cross-sectional area of 9 of 11 large cerebral arteries. Global microvascular perfusion (ASL) was reduced by L-NMMA (L-NMMA: 42 ± 7 vs. placebo: 47 ± 8 ml/100g/min, P = 0.02), with 7-11% reductions in both hemispheres of the frontal, parietal and temporal lobes, and in the left occipital lobe. We conclude that NO contributes to macrovascular and microvascular regulation including larger artery resting diameter. Contrary to our hypothesis, the influence of NO on cerebral perfusion appears regionally uniform in healthy young adults. KEY POINTS: Cerebral blood flow (CBF) is vital for brain health, but the signals that are key to regulating CBF remain unclear. Nitric oxide (NO) is produced in the brain, but its importance in regulating CBF remains controversial since prior studies have not studied all regions of the brain simultaneously. Using modern MRI approaches, a drug that inhibits the enzymes that make NO (L-NMMA) reduced CBF by up to 11% in different brain regions. NO helps maintain proper CBF in healthy adults. These data will help us understand whether the reductions in CBF that occur during ageing or cardiovascular disease are related to shifts in NO signalling.

Concentrations of Circulating Phylloquinone, but Not Cerebral Menaquinone-4, Are Positively Correlated with a Wide Range of Cognitive Measures: Exploratory Findings in Centenarians

BACKGROUND

Vitamin K (VK) exists in the form of phylloquinone (PK) and menaquinones (MKs). Roles of VK on cognitive health in the elderly are emerging, but there is limited evidence on VK uptake and metabolism in human brain.

OBJECTIVES

The primary objective of this study was to characterize VK distribution in brains of an elderly population with varied cognitive function. In addition, associations among circulating (a biomarker of VK intake) and cerebral VK concentrations and cognition were investigated.

METHODS

Serum or plasma (n = 27) and brain samples from the frontal cortex (FC; n = 46) and the temporal cortex (TC; n = 33) were acquired from 48 decedents (aged 98-107 y; 25 demented and 23 nondemented) enrolled in the Georgia Centenarian Study. Both circulating and brain VK concentrations were measured using HPLC with fluorescence detection. Cognitive assessment was performed within 1 y prior to mortality. Partial correlations between serum/plasma or cerebral VK concentrations and cognitive function were performed, adjusting for covariates and separating by dementia and antithrombotic use.

RESULTS

MK-4 was the predominant vitamer in both FC (mean ± SD = 4.92 ± 2.31 pmol/g, ≥89.15% ± 5.09% of total VK) and TC (4.60 ± 2.11 pmol/g, ≥89.71% ± 4.43% of total VK) regardless of cognitive status. Antithrombotic users had 34.0% and 53.9% lower MK-4 concentrations in FC (P < 0.05) and TC (P < 0.001), respectively. Circulating PK was not correlated with cerebral MK-4 or total VK concentrations. Circulating PK concentrations were significantly associated with a wide range of cognitive measures in nondemented centenarians (P < 0.05). In contrast, cerebral MK-4 concentrations were not associated with cognitive performance, either before or after exclusion of antithrombotic users.

CONCLUSIONS

Circulating VK concentrations are not related to cerebral MK-4 concentrations in centenarians. Cerebral MK-4 concentrations are tightly regulated over a range of VK intakes and cognitive function. Circulating PK may reflect intake of VK-rich foods containing other dietary components beneficial to cognitive health. Further investigation of VK uptake and metabolism in the brain is warranted.

Reactive hyperemia index (RHI) and cognitive performance indexes are associated with histologic markers of liver disease in subjects with non-alcoholic fatty liver disease (NAFLD): a case control study

BACKGROUND

No study evaluated vascular health markers in subjects with non-alcoholic fatty liver disease (NAFLD) through a combined analysis of reactive hyperemia peripheral arterial tonometry (RH-PAT) and arterial stiffness indexes.

AIM OF THE STUDY

We aimed to assess whether NAFLD and its histological severity are associated with impairment of arterial stiffness and RH-PAT indexes in a mixed cohort of patients with biopsy-proven NAFLD.

MATERIALS AND METHODS

The Kleiner classification was used to grade NAFLD grade. Pulse wave velocity (PWV) and augmentation index (Aix) were used as markers of arterial stiffness, whereas endothelial function was assessed using reactive hyperemia index (RHI). The mini-mental state examination (MMSE) was administered to test cognitive performance.

RESULTS

80 consecutive patients with biopsy-proven NAFLD and 83 controls without fatty liver disease. NAFLD subjects showed significantly lower mean RHI, higher mean arterial stiffness indexes and lower mean MMSE score. Multivariable analysis after correction for BMI, dyslipidaemia, hypertension, sex, diabetes, age and cardiovascular disease showed that BMI, diastolic blood pressure and RHI are significantly associated to NAFLD. Simple linear regression analysis showed among non-alcoholic steatohepatitis (NASH) subjects a significant negative relationship between ballooning grade and MMSE and a significant positive association between Kleiner steatosis grade and augmentation index.

CONCLUSIONS

Future research will be addressed to evaluate the relationship between inflammatory markers and arterial stiffness and endothelial function indexes in NAFLD subjects. These study will evaluate association between cardiovascular event incidence and arterial stiffness, endothelial and cognitive markers, and they will address the beneficial effects of cardiovascular drugs such as statins and ACE inhibitors on these surrogate markers in NAFLD subjects.

Risk of Alzheimer's disease incidence attributable to vascular disease in the population

BACKGROUND

Although Alzheimer's disease (AD) is a neurodegenerative disorder, there is growing interest in the influence of vascular factors on its incidence.

METHODS

In a population-based longitudinal epidemiological study, we fit Cox proportional hazard models to examine the risk of incident dementia and AD associated with self-reported vascular disease. The population-attributable risk percent (percent of the incidence of dementia and AD in the population that would be eliminated if vascular disease was eliminated) was calculated using the adjusted hazard ratios (HR).

RESULTS

Of 822 eligible participants, 94 individuals developed incident dementia, with 79 having AD (probable/possible AD) during the follow-up period of on average 8 years. Stroke/transient ischemic attack history was associated with incident dementia (HR=2.6) as well as AD (HR=2.4) among non-apolipoprotein E ɛ4 carriers.

CONCLUSIONS

At the community level, the risk of dementia could be potentially reduced by 10.8% by eliminating overt cerebrovascular disease, and the risk of AD by 9.1% for non-apolipoprotein E ɛ4 carriers.

The aging mind: vascular health in normal cognitive aging

In spite of the breakneck speed at which understanding of the biological basis of the aging process has evolved, the important determinants of aging and longevity have yet to be uncovered. The preservation of cognitive functioning is an essential component of successful aging, and the ability to distinguish those who maintain cognitive health into advanced age from those who experience cognitive decline may influence public health efforts to prevent or delay the onset of cognitive impairment in old age. There is growing evidence implicating vascular risk factors and related subclinical cerebrovascular damage in cognitive impairment and dementia, but Alzheimer's disease is highly prevalent in older populations, and the role of inflammation in vascular and neurodegenerative processes is poorly understood. There is a growing need to examine the effects of these factors on normal cognitive aging. This brief survey of the literature reviews evidence of the roles of subclinical vascular brain damage and exposure to cerebrovascular risk factors in normal cognitive aging.