Emerging Links between Cerebral Blood Flow Regulation and Cognitive Decline: A Role for Brain Microvascular Pericytes

Large inter-arm systolic blood pressure difference is associated with cognitive impairment in older adults: a cross-sectional study in rural southwest China

Background

Studies have shown that both inter-arm blood pressure difference (IABPD) and cognitive impairment are associated with vascular events. However, the relationship between IABPD and cognitive impairment among elderly individuals in rural China remains unclear. This study aims to investigate the association between IABPD and cognitive impairment in rural older adults in Guizhou, southwestern China.

Methods

The study data were obtained from the Cohort Study of the Health Status of Guizhou Rural Older Adults in China (SHGROC). A multi-stage cluster sampling method was employed to select 1,088 rural elderly individuals aged ≥ 60 years from Guizhou Province for questionnaire surveys, physical examinations, and biological sample collection. Cognitive function of participants was assessed using the Mini-Mental State Examination (MMSE). Bilateral blood pressure was measured simultaneously using an automated device, and the IABPD was calculated. Multivariable linear and logistic regression models were used to examine the relationship between IABPD and cognitive impairment.

Results

The overall prevalence of cognitive impairment in the study sample was 27.85%, and it was more common among participants with an IABPD ≥ 10 mmHg (P < 0.05). Multivariable regression analysis revealed that an inter-arm systolic blood pressure difference (IASBPD) ≥ 10 mmHg was independently associated with lower MMSE scores (β = -1.113; 95% CI: -2.120, -0.106; P = 0.030) and a higher risk of cognitive impairment (OR = 1.902; 95% CI: 1.189, 3.040; P = 0.007). Additionally, a dose-response relationship was observed between IASBPD and the risk of cognitive impairment, with a linear positive correlation. Further subgroup analysis indicated that the relationship between IASBPD and cognitive impairment was modified by sex, smoking, and regular exercise (P for interaction < 0.05).

Conclusion

IASBPD ≥ 10 mmHg is associated with an increased risk of cognitive impairment in rural Chinese older adults. This suggested that IASBPD may provide a reference for early identification of individuals at risk of cognitive impairment.

Multi-target approach to Alzheimer's disease prevention and treatment: antioxidant, anti-inflammatory, and amyloid- modulating mechanisms

Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) plaque accumulation, neurofibrillary tangles, neuroinflammation, and progressive cognitive decline, posing a significant global health challenge. Growing evidence suggests that dietary polyphenols may reduce the risk and progression of AD through multifaceted neuroprotective mechanisms. Polyphenols regulate amyloid proteostasis by inhibiting β/γ-secretase activity, preventing Aβ aggregation, and enhancing clearance pathways. Their strong antioxidant properties neutralize reactive oxygen species, chelate redox-active metals, and activate cytoprotective enzymes via Nrf2 signaling. This review examines the potential therapeutic targets, signaling pathways, and molecular mechanisms by which dietary polyphenols exert neuroprotective effects in AD, focusing on their roles in modulating amyloid proteostasis, oxidative stress, neuroinflammation, and cerebrovascular health. Polyphenols mitigate neuroinflammation by suppressing NF-κB signaling and upregulating brain-derived neurotrophic factor, supporting neuroplasticity and neurogenesis. They also enhance cerebrovascular health by improving cerebral blood flow, maintaining blood-brain barrier integrity, and modulating angiogenesis. This review examines the molecular and cellular pathways through which polyphenols exert neuroprotective effects, focusing on their antioxidant, anti-inflammatory, and amyloid-modulating roles. We also discuss their influence on key AD pathologies, including Aβ deposition, tau hyperphosphorylation, oxidative stress, and neuroinflammation. Insights from clinical and preclinical studies highlight the potential of polyphenols in preventing or slowing AD progression. Future research should explore personalized dietary strategies that integrate genetic and lifestyle factors to optimize the neuroprotective effects of polyphenols.

Hippocampal vascularization pattern and cerebral blood flow cooperatively modulate hippocampal tolerable amount of Aβ deposition in the occurrence of MCI

BACKGROUND

Aβ deposition in the brain does not necessarily lead to cognitive impairment, and that blood supply may have other unexplained regulatory effects on Aβ. Therefore, there appears to be a more complex relationship between blood supply, Aβ deposition, and cognitive impairment that warrants further exploration.

METHODS

This cohort study collected four longitudinal follow-up datasets, including a total of 281 subjects, followed for four years. Three-dimensional time-of-flight angiography and pseudo-continuous arterial spin labeling were used to assess hippocampal vascularization pattern (VP) and hippocampal cerebral blood flow (CBF). 11 C-Pittsburgh compound B (PiB)-PET/CT-based spatial measurements were used detect hippocampal PiB uptake as a reflection of hippocampal Aβ deposition. We explored the relationships between hippocampal blood supply (VP and CBF), hippocampal PiB uptake, and the occurrence of mild cognitive impairment (MCI) using a generalized nonlinear model.

RESULTS

We demonstrated the synergistic effect of hippocampal VP and CBF on predicting the occurrence of MCI. We conducted confirmation and quantification of the relationship between hippocampal blood supply and hippocampal PiB uptake. Additionally, the predicted value of PiB uptake based on hippocampal blood supply not only exhibited strong predictive efficacy for the occurrence of MCI (AUC = 0.831, p < 0.001), but was also validated in cerebral small vessel disease cohorts (AUC = 0.792, p < 0.001) and well validated in an independent cohort (Kappa = 0.741, p < 0.001).

CONCLUSIONS

Overall, we reveal that hippocampal blood supply at baseline can regulate hippocampal PiB uptake, which reflects hippocampal tolerable amount of Aβ deposition and serves as an effective predictor for the occurrence of MCI, providing an important extension on the relationship between hippocampal blood supply and Aβ deposition.

Apelin Receptor Homodimerisation Inhibits Hippocampal Neuronal Autophagy via G Protein-Dependent Signalling in Vascular Dementia

Vascular dementia (VD), a progressive vascular cognitive impairment, is characterised by the presence of cerebral hypoperfusion, increased blood-brain barrier permeability, and white matter lesions. Although current treatment strategies primarily focus on risk factors such as hypertension, diabetes, and heart disease, efficient and targeted therapies are lacking and the underlying mechanisms of VD remain unclear. We previously discovered that Apelin receptors (APJ), which are G protein-coupled receptors (GPCRs), can homodimerize and generate signals that are distinct from those of APJ monomers in VD rats. Apelin-13 reduces the level of APJ homodimers and leads to the proliferation of endogenous neural stem cells in the hippocampal dentate gyrus area, suggesting that it has a neuroprotective role. In this study, we established a rat and cellular oxygen-glucose deprivation/reoxygenation VD model to investigate the impact of APJ homodimerisation on autophagy. We found that APJ homodimers protect against VD by inhibiting autophagy through the Gαq and PI3K/Akt/mTOR pathways upon Gαi signalling, both in vivo and in vitro. This discovery provides a promising therapeutic target for chronic cerebral ischaemia-reperfusion diseases and an experimental foundation for the development of drugs that target APJ homodimers.

Pinaffi-Langley AC, Peterfi A, Mukli P, Detwiler S, Olay L, Kaposzta Z, Smith K, Kirkpatrick AC, Saleh Velez F, Tarantini S, Csiszar A, Ungvari ZI, Prodan CI, Yabluchanskiy A. COVID-19 Exacerbates Neurovascular Uncoupling and Contributes to Endothelial Dysfunction in Patients with Mild Cognitive Impairment

Mild cognitive impairment (MCI) affects nearly 20% of older adults worldwide, with no targetable interventions for prevention. COVID-19 adversely affects cognition, with >70% of older adults with Long COVID presenting with cognitive complaints. Neurovascular coupling (NVC), an essential mechanism of cognitive function, declines with aging and is further attenuated in neurocognitive disorders. The effect of COVID-19 on NVC responses has yet to be addressed in older adults who are vulnerable to dementia progression. Participants with MCI and a history of COVID-19 (COV+, N = 31) and MCI participants with no history of infection (COV- N = 11) participated in this cross-sectional study to determine if COVID-19 affects cerebrocortical NVC responses and vascular function. Functional near-infrared spectroscopy was used to measure cerebrocortical NVC responses, and endothelial function was assessed via insonation of the brachial artery during a flow-mediated dilation protocol. NVC responses were elicited by the working memory n-back paradigm. NVC in the left dorsolateral prefrontal cortex and endothelial function was decreased in the COV+ group compared to the COV- group. These data provide mechanistic insight into how COVID-19 may exacerbate long-term cognitive sequela seen in older adults, highlighting the urgent need for further research and clinical trials to explore novel therapeutic interventions aimed at preserving/restoring NVC.

Contrast-Enhanced Ultrasound Imaging Detects Anatomical and Functional Changes in Rat Cervical Spine Microvasculature With Normal Aging

Normal aging is associated with significant deleterious cerebrovascular changes; these have been implicated in disease pathogenesis and increased susceptibility to ischemic injury. Although these changes are well documented in the brain, few studies have been conducted in the spinal cord. Here, we utilize specialized contrast-enhanced ultrasound (CEUS) imaging to investigate age-related changes in cervical spinal vascular anatomy and hemodynamics in male Fisher 344 rats, a common strain in aging research. Aged rats (24-26 months, N = 6) exhibited significant tortuosity in the anterior spinal artery and elevated vascular resistance compared to adults (4-6 months, N = 6; tortuosity index 2.20 ± 0.15 vs 4.74 ± 0.45, p < .05). Baseline blood volume was lower in both larger vessels and the microcirculation in the aged cohort, specifically in white matter (4.44e14 ± 1.37e13 vs 3.66e14 ± 2.64e13 CEUS bolus area under the curve, p < .05). To elucidate functional differences, animals were exposed to a hypoxia challenge, whereas adult rats exhibited significant functional hyperemia in both gray matter (GM) and white matter (WM) (GM: 1.13 ± 0.10-fold change from normoxia, p < .05; WM: 1.16 ± 0.13, p < .05), aged rats showed no response. Immunohistochemistry revealed reduced pericyte coverage and activated microglia behavior in aged rats, which may partially explain the lack of vascular response. This study provides the first in vivo description of age-related hemodynamic differences in the cervical spinal cord.

Effects of high-intensity interval training in a cold environment on arterial stiffness and cerebral hemodynamics in sedentary Chinese college female students post-COVID-19

Many patients with COVID-19 experience increased arterial stiffness and abnormal cerebral hemodynamics. Although previous studies have explored the effects of cold environments on cardiovascular health and cerebral hemodynamics, there is still no research on the changes in cardiovascular and cerebral hemodynamics in sedentary female students recovering from COVID-19 while performing high-intensity interval training (HIIT) in cold environments. This study investigates the effects of 1 week of HIIT in a cold environment on cerebral hemodynamics and arterial stiffness (AS) in sedentary female college students, providing new insights into the pathophysiological mechanisms in this specific context. Thirty-six participants were randomly divided into a control group (n = 12), a room temperature (RE) group (n = 12), and a cold environment (CE) group (n = 12). HIIT was performed for four 4-min running training sessions, with a 4-min interval between each training session, The training duration was 1 week, with a frequency of 2 sessions per day, while the control group did not undergo any training. After training, the AS in the CE group significantly decreased (p < 0.05), with an average reduction of 11% in brachial-ankle pulse wave velocity, showing a significantly greater improvement compared to the RE group and the control group (p < 0.05), while no significant changes were observed in the RE group (p > 0.05). In the Y-Balance Tests (YBTs), the concentrations of cerebral oxygenated hemoglobin and total hemoglobin significantly increased (p < 0.05) during unilateral leg support tests in both the CE and RE groups, and the increase of CE group is greater than that of RE group. In contrast, in the control group, the concentrations of cerebral oxygenated hemoglobin and total hemoglobin significantly decreased during left leg support (p < 0.05). Our study found that performing HIIT in a cold environment not only effectively reduces AS in sedentary female college students after COVID-19, improves cardiovascular function, but also significantly enhances cerebral hemodynamics, helping them alleviate the negative impacts of post-COVID-19 sequelae and sedentary behavior on health. Future research should further explore the mechanisms by which sedentary behavior, post-COVID-19 recovery status, and adaptation to cold environments collectively influence cardiovascular function and cerebral hemodynamics, providing a more comprehensive understanding of these factors.

Remote ischemic conditioning prevents ischemic cerebrovascular events in children with moyamoya disease: a randomized controlled trial

BACKGROUND

Moyamoya disease (MMD) is a significant cause of childhood stroke and transient ischemic attacks (TIAs). This study aimed to assess the safety and efficacy of remote ischemic conditioning (RIC) in children with MMD.

METHODS

In a single-center pilot study, 46 MMD patients aged 4 to 14 years, with no history of reconstructive surgery, were randomly assigned to receive either RIC or sham RIC treatment twice daily for a year. The primary outcome measured was the cumulative incidence of major adverse cerebrovascular events (MACEs). Secondary outcomes included ischemic stroke, recurrent TIA, hemorrhagic stroke, revascularization rates, and clinical improvement assessed using the patient global impression of change (PGIC) scale during follow-up. RIC-related adverse events were also recorded, and cerebral hemodynamics were evaluated using transcranial Doppler.

RESULTS

All 46 patients completed the final follow-up (23 each in the RIC and sham RIC groups). No severe adverse events associated with RIC were observed. Kaplan-Meier analysis indicated a significant reduction in MACEs frequency after RIC treatment [log-rank test (Mantel-Cox), P = 0.021]. At 3-year follow-up, two (4.35%) patients had an ischemic stroke, four (8.70%) experienced TIAs, and two (4.35%) underwent revascularization as the qualifying MACEs. The clinical improvement rate in the RIC group was higher than the sham RIC group on the PGIC scale (65.2% vs. 26.1%, P < 0.01). No statistical difference in cerebral hemodynamics post-treatment was observed.

CONCLUSIONS

RIC is a safe and effective adjunct therapy for asymptomatic children with MMD. This was largely due to the reduced incidence of ischemic cerebrovascular events.

Pericyte Dysfunction Contributes to Vascular Cognitive Impairment Induced by Chronic Cerebral Hypoperfusion in Rats

Vascular cognitive impairment (VCI) encompasses cognitive disorders associated with cerebrovascular disease, often manifesting as white matter lesions (WMLs), irrespective of precise triggers. The integrity of white matter is essential for neural communication and cognitive function maintenance. Persistent cerebral hypoperfusion-induced WMLs are now acknowledged as a key driver of VCI and dementia, though their exact formation mechanism remains unclear. Recent studies link pericyte dysfunction to diverse brain disorders like Alzheimer disease. However, the exact pathological connection between pericyte dysfunction and cognitive impairment in VCI remains unexplored. In this study, we aimed to examine whether pericyte dysfunction could impact WMLs and cognitive impairment in a rat VCI model. Using a rat model of chronic cerebral hypoperfusion-induced VCI through two-vessel occlusion (2VO), we verified that 2VO induced both WMLs and cognitive impairment. Notably, the number of pericytes in the brain was significantly altered after 2VO. Furthermore, we observed significantly increased capillary constrictions at pericyte bodies in the brains of 2VO-induced rats compared to sham-operated rats, accompanied by reduced cerebral blood flow (CBF). To tackle this issue, we administered CGS21680, a specific adenosine A2A subtype receptor agonist, intranasally twice a day for 7 days. We found that rats treated with CGS21680 exhibited a significant increase in CBF at 7 and 14 days after 2VO, compared to the vehicle group. Moreover, capillary lumens beneath pericytes also increased after the CGS21680 treatment. Importantly, the treatment led to substantial improvements in WMLs and cognitive impairment compared to the vehicle group. Our findings suggest a critical role of pericyte dysfunction in WMLs and cognitive impairment within the rat VCI model. This insight contributes to our understanding of pathogenesis and offers prospects for targeted intervention in VCI.

Cognitive impairment and hippocampal neuronal damage in β-thalassaemia mice

β-Thalassaemia is one of the most common genetic diseases worldwide. During the past few decades, life expectancy of patients has increased significantly owing to advance in medical treatments. Cognitive impairment, once has been neglected, has gradually become more documented. Cognitive impairment in β-thalassaemia patients is associated with natural history of the disease and socioeconomic factors. Herein, to determined effect of β-thalassaemia intrinsic factors, 22-month-old β-thalassaemia mouse was used as a model to assess cognitive impairment and to investigate any aberrant brain pathology in β-thalassaemia. Open field test showed that β-thalassaemia mice had decreased motor function. However, no difference of neuronal degeneration in primary motor cortex, layer 2/3 area was found. Interestingly, impaired learning and memory function accessed by a Morris water maze test was observed and correlated with a reduced number of living pyramidal neurons in hippocampus at the CA3 region in β-thalassaemia mice. Cognitive impairment in β-thalassaemia mice was significantly correlated with several intrinsic β-thalassaemic factors including iron overload, anaemia, damaged red blood cells (RBCs), phosphatidylserine (PS)-exposed RBC large extracellular vesicles (EVs) and PS-exposed medium EVs. This highlights the importance of blood transfusion and iron chelation in β-thalassaemia patients. In addition, to improve patients' quality of life, assessment of cognitive functions should become part of routine follow-up.

Contrast-enhanced ultrasound imaging detects anatomical and functional changes in rat cervical spine microvasculature with normal aging

Normal aging is associated with significant deleterious cerebrovascular changes; these have been implicated in disease pathogenesis and increased susceptibility to ischemic injury. While these changes are well documented in the brain, few studies have been conducted in the spinal cord. Here, we utilize specialized contrast-enhanced ultrasound (CEUS) imaging to investigate age-related changes in cervical spinal vascular anatomy and hemodynamics in male Fisher 344 rats, a common strain in aging research. Aged rats (24-26 mo., N=6) exhibited significant tortuosity in the anterior spinal artery and elevated vascular resistance compared to adults (4-6 mo., N=6; tortuosity index 2.20±0.15 vs 4.74±0.45, p<0.05). Baseline blood volume was lower in both larger vessels and the microcirculation in the aged cohort, specifically in white matter (4.44e14±1.37e13 vs 3.66e14±2.64e13 CEUS bolus AUC, p<0.05). To elucidate functional differences, animals were exposed to a hypoxia challenge; whereas adult rats exhibited significant functional hyperemia in both gray and white matter (GM: 1.13±0.10-fold change from normoxia, p<0.05; WM: 1.16±0.13, p<0.05), aged rats showed no response. Immunohistochemistry revealed reduced pericyte coverage and activated microglia behavior in aged rats, which may partially explain the lack of vascular response. This study provides the first in vivo description of age-related hemodynamic differences in the cervical spinal cord.

Impacts of futile reperfusion and reperfusion injury in acute ischemic stroke

Acute ischemic stroke (AIS) remains to be a challenging cerebrovascular disease. The mainstay of AIS management is endovascular reperfusion therapy, including thrombectomy and thrombolysis. However, ineffective (futile) reperfusion (FR) or reperfusion injury (RI) can be seen in a significant number of patients undergoing reperfusion strategy. In this article, we discuss two clinically relevant concepts known as "time window" and "tissue window" that can impact the clinical outcome of reperfusion therapy. We also explore patient risk factors, leading to FR and RI as well as an emerging concept of "no-reflow phenomenon" seen in ineffective reperfusion. These fundamental concepts provide insight into the clinical management of AIS patients and provide references for future research.

Endothelial Cell APOE3 Regulates Neurovascular, Neuronal, and Behavioral Function

BACKGROUND

Specialized brain endothelial cells and human APOE3 are independently important for neurovascular function, yet whether APOE3 expression by endothelial cells contributes to brain function is currently unknown. In the present study, we determined whether the loss of endothelial cell APOE3 impacts brain vascular and neural function.

METHODS

We developed APOE3fl/fl/Cdh5(PAC)-CreERT2+/- (APOE3Cre+/-) and APOE3fl/fl/Cdh5(PAC)-CreERT2-/- (APOE3Cre-/-, control) mice and induced endothelial cell APOE3 knockdown with tamoxifen at ≈4 to 5 weeks of age. Neurovascular and neuronal function were evaluated by biochemistry, immunohistochemistry, behavioral testing, and electrophysiology at 9 months of age.

RESULTS

We found that the loss of endothelial APOE3 expression was sufficient to cause neurovascular dysfunction including higher permeability and lower vessel coverage in tandem with deficits in spatial memory and fear memory extinction and a disruption of cortical excitatory/inhibitory balance.

CONCLUSIONS

Our data collectively support the novel concept that endothelial APOE3 plays a critical role in the regulation of the neurovasculature, neural circuit function, and behavior.