Relationship between cognitive function and regulation of cerebral blood flow

Ketone ester ingestion impairs exercise performance without impacting cognitive function or circulating EPO during acute hypoxic exposure

Altitude-induced hypoxemia impairs exercise performance and cognition. Interestingly, ketone ester (KE) ingestion may attenuate hypoxemia, which likely explains the observation that KE impairs high-intensity exercise performance in normoxia but not in hypoxia. Moreover, KE was reported to attenuate cognitive decline at extreme altitudes (∼6,100 m). Given that hypoxemia is unaffected by KE in milder conditions, the impact of KE on cognition and performance in the absence of elevated oxygenation remains unknown. As KE may increase postexercise circulating [erythropoietin] ([EPO]) at sea level, we also assessed if KE might augment the blood [EPO] response after hypoxic exercise. In a double-blind, cross-over design, 13 healthy, male participants completed two 5.5-h sessions at 4,000-m simulated altitude while receiving either KE or placebo (CON). Throughout a graded exercise test (EXMAX) after 1.5 h, and a submaximal exercise bout (EXSUBMAX) after 3 h, blood and tissue oxygenation, ventilatory parameters, and acid-base balance were evaluated. Other measurements included cognitive function and blood [EPO]. KE reduced power output achieved during EXMAX by 3.6%, whereas blood and cerebral oxygenation were similar. KE ingestion lowered blood pH, [[Formula: see text]], pCO2, and [glucose], but did not impact cognitive function. In both KE and CON, circulating [EPO] increased by ∼56% after 5 h. These results indicate that KE ingestion impairs high-intensity exercise performance, at least if not compensated by elevated oxygenation. A progressively increasing oxygenation upon KE was unable to protect against hypoxia-induced cognitive declines and potentially counteracted a KE-induced augmentation of circulating [EPO].NEW & NOTEWORTHY This study is the first to show that KE ingestion impairs exercise performance in hypoxia, at least when KE does not alleviate hypoxemia. Despite a subsequent, progressive increase in oxygenation upon KE after 3-4 h, this does not protect against hypoxia-induced cognitive declines. Although studies in normoxia show potential of KE to increase blood [erythropoietin], we identified that KE ingestion fails to augment the increase in blood [erythropoietin] through hypoxic exposure and exercise.

An exaggerated blood pressure response to exercise is associated with attenuated exercise-induced acute cognitive improvement: A pilot study

Some individuals, despite having normal resting blood pressure, exhibit an exaggerated blood pressure response during exercise, indicating a potential risk for future hypertension. This study aimed to investigate how different individual blood pressure responses to exercise affect cerebral circulation and exercise-induced acute cognitive changes in young, healthy individuals. To eliminate the influence of aging and disease, thirty young, healthy individuals (aged 21 ± 1 years) participated in this study. They performed an interval static handgrip exercise protocol, during which arterial blood pressure (ABP), cognitive function, and middle cerebral artery blood velocity (MCA V), as an index of cerebral blood flow, were measured. Cognitive function was assessed using the Go/No-go test before exercise and 3 min after exercise completion. Individual changes in systolic blood pressure (SBP) were significantly and linearly related to the decrease in reaction time during a cognitive task, indicating cognitive improvement following exercise (p < 0.01). Importantly, in the top 10 subjects with the highest SBP responses (n = 10, + 38 ± 8 mm Hg), this cognitive improvement was not statistically significant (p = 0.32). These findings suggest that an exaggerated ABP response to exercise may compromise acute cognitive enhancements induced by exercise in young individuals.

Can supplementation with antioxidants improve cognitive functions in patients with multiple sclerosis? A literature review

Multiple sclerosis (MS) is a chronic neuroinflammatory and neurodegenerative disease of the central nervous system (CNS) with a complex and multifactorial pathophysiology. Although these mechanisms are not yet fully elucidated, it is established that oxidative stress (OS) plays a key role in driving neurodegeneration in MS. These pathological mechanisms contribute to a wide range of symptoms, including motor and sensory deficits, as well as cognitive impairment. The impairments in cognitive functions can cause a major burden for these patients and significantly affect their quality of life. For example, memory is one of the most frequently impaired cognitive domains in MS. These deficits often correlate with biomarkers of neurodegeneration and disease progression. Despite the substantial burden of cognitive impairment in MS, no established treatments currently exist to prevent or mitigate cognitive decline in these patients, aside from the disease-modifying treatments. Several clinical trials have investigated the potential of antioxidant supplementation to improve cognitive outcomes in MS patients. However, their findings are often controversial. This review discusses trials evaluating the effects of supplementation with various antioxidants, including Ginkgo biloba, melatonin, omega-3 fatty acids, vitamins A, N-acetylcysteine, lipoic acid, xanthophylls, and crocin, on cognitive performance. We discuss the findings of these studies, highlight methodological limitations, and explore the underlying mechanisms by which these compounds may modulate cognition. These mechanisms range from mitigating OS, inflammation, and glutamate-induced neurotoxicity in the CNS to addressing secondary symptoms such as depression and fatigue, which are often linked to cognitive decline. By reviewing the current evidence, this review not only underscores the therapeutic potential and limitations of antioxidant supplementation but also provides guidance for future research to optimize study design and advance our understanding of cognitive preservation strategies in MS.

Resting-state hemodynamic changes and effects on upper limb function after multi-channel transcranial direct current stimulation to the ipsilesional primary motor cortex and anterior intraparietal sulcus in stroke patients: an fNIRS pilot study

BACKGROUND

Stroke results in substantial long-term disability, necessitating effective recovery interventions. This study explored the effects of multi-channel transcranial direct current stimulation (tDCS) on hemodynamic responses and upper limb motor function in stroke patients, targeting the ipsilesional primary motor cortex (M1) and anterior intraparietal sulcus (aIPS).

METHODS

A double-blind, randomized, sham-controlled trial was conducted with 24 stroke patients (18 men; mean age, 57.3×14.2 years), who underwent 10 sessions of real or sham multi-channel tDCS combined with upper limb exercises. Functional near-infrared spectroscopy (fNIRS) measured resting-state cerebral hemodynamic responses for 5 min before and after each session. Motor function was evaluated using the Fugl-Meyer assessment for upper extremity (FMA-UE), box and block test (BBT), and other motor function tests before and after the interventions.

RESULTS

The real multi-channel tDCS group exhibited increases in regional accumulation of oxyhemoglobin (HbOAcc) and stronger seeded connectivity networks within the motor cortex poststimulation. In contrast, the sham group exhibited disassociation from these areas. The group × time interaction was significant for the Box and Block Test (BBT), indicating greater improvements in gross manual dexterity in the real-tDCS group compared to the sham group. While poststimulation changes in HbOAcc were examined in relation to FMA-UE scores, no strong linear relationship was observed in the real-tDCS group.

CONCLUSIONS

Multi-channel tDCS targeting the ipsilesional M1 and aIPS, combined with upper limb exercises, showed potential effects on cerebral hemodynamics and motor function in stroke patients. These findings suggest that multi-channel tDCS may have a role in motor rehabilitation, but further research is needed to validate its efficacy and clinical applicability.

CLINICALTRIALS

GOV: This study was registered at ClinicalTrials.gov (NCT05275114).

Imaging the cerebral vasculature at different scales: translational tools to investigate the neurovascular interfaces

The improvements in imaging technology opened up the possibility to investigate the structure and function of cerebral vasculature and the neurovascular unit with unprecedented precision and gaining deep insights not only on the morphology of the vessels but also regarding their function and regulation related to the cerebral activity. In this review, we will dissect the different imaging capabilities regarding the cerebrovascular tree, the neurovascular unit, the haemodynamic response function, and thus, the vascular-neuronal coupling. We will discuss both clinical and preclinical setting, with a final discussion on the current scenery in cerebrovascular imaging where magnetic resonance imaging and multimodal microscopy emerge as the most potent and versatile tools, respectively, in the clinical and preclinical context.

Effects of exercise on older adults with mild cognitive impairment: A systematic review and network meta-analysis

Background: Mild cognitive impairment (MCI) represents a transitional stage between normal aging and Alzheimer's disease (AD), with a significantly elevated risk of progressing to AD. In recent years, accumulating evidence has indicated that exercise interventions may mitigate cognitive decline in individuals with MCI and reduce the risk of conversion to AD, potentially through mechanisms such as enhancing cerebral blood flow and promoting neuroplasticity. Objective: To explore which type of exercise is most effective in improving global cognition in older adults with MCI and to investigate whether exercise can enhance their balance abilities. Methods: Randomized controlled trials were retrieved from four databases. Stata software was used for Network Meta-Analysis and traditional meta-analysis. Results: A total of 33 studies were included, of which 28 were used to determine the best exercise modality. The results indicated that multicomponent exercise (SUCRA = 76.5%) and moderate-intensity aerobic exercise (SUCRA = 73.6%) are two effective modalities. The results of the traditional meta-analysis showed that exercise combined with cognitive training, moderate-intensity aerobic exercise, resistance exercise, and land-based kayaking training can improve balance ability. Conclusions: Multicomponent exercise may be the optimal exercise modality for enhancing global cognition in older adults with MCI, and various exercise modalities can improve balance abilities. However, more studies with larger sample sizes and higher quality are needed to provide further evidence.

The impact of brain-systemic oxygenation coupling in sleep-disordered breathing on cognitive function in elderly

BACKGROUND

Intermittent hypoxia, a consequence of sleep-disordered breathing (SDB), may contribute to an increased risk of cognitive decline. However, the association between SDB and cognition remains highly variable.

METHODS

Fifty-two community-dwelling healthy older adults (28 women) were recruited. All participants underwent neuropsychiatric evaluations, simultaneous ambulatory polysomnography (PSG), and near-infrared spectroscopy (NIRS) recordings. We quantified the average coherence between oxy-Hb and SpO2 signals during SDB events to determine whether it could predict cognitive outcomes in healthy older adults, where higher coherence indicates reduced protection against systemic hypoxia.

RESULTS

The mean (SD) coherence of oxy-Hb and SpO2 was 0.16 (0.07). Linear regression analysis showed a significant association between mean coherence and worse Stroop Color Word Test scores (t=-0.304, p = .004). In contrast, oxy-Hb reduction alone and conventional SDB parameters did not show a significant association with cognition.

CONCLUSION

This is the first report to demonstrate an association between a novel parameter of brain-systemic oxygenation coherence in SDB and cognition in older adults. A higher coherence rate of cortical oxy-Hb and systemic SpO2 during SDB may reflect a loss of compensatory mechanisms against systemic hypoxia and could help stratify older adults with a higher risk for cognitive decline.

Effects of Sitting Baduanjin Exercises on Cognitive Function, Attention, and Muscle Strength among Patients with Mild Cognitive Impairment

PURPOSE

Sitting Baduanjin exercises can be effective in treating mild cognitive impairment (MCI). However, evidence on effectiveness of sitting Baduanjin exercises is lacking. This study investigated the effects of sitting Baduanjin exercises on cognitive function, attention, and muscle strength in patients with MCI.

DESIGN

Quasi-experimental.

METHODS

The participants were assigned to the experimental (n = 12) or comparison group (n = 12). The experimental group performed sitting Baduanjin exercises three times weekly for 40-50 minutes per session for 12 weeks, while the comparison group maintained their usual routine and attended health-related education. The two groups' cognitive function and attention were assessed through a questionnaire and their muscle strength was measured at weeks 0, 9, and 13.

FINDINGS

The experimental group showed significant improvements in cognitive function, attention, and muscle strength in the right shoulder anterior flexor; however, the left shoulder anterior flexor group showed no obvious improvements.

CONCLUSION

Sitting Baduanjin exercises feature simple actions, are convenient, and have positive effects on improving cognitive function, attention, and muscle strength in patients with MCI.

CLINICAL EVIDENCE

Baduanjin exercises are suitable for long-term community frontline care services. Early intervention with this exercise program may prevent healthy older people or those with health issues from progressing to dementia.

The Influence of Sex, Fitness, BMI, and Cardiovascular Risk Factors on Cerebral Blood Velocity Responsiveness to Graded Exercise Testing in Middle-Aged Adults

Mean middle cerebral artery velocity (MCAv) and the pulsatility index (PI), at rest and in response to exercise, are important markers of cerebrovascular health status in middle-aged adults, when vascular decline assumes substantial relevance. Thus, this study aimed to describe and compare the responses of MCAv and PI to incremental exercise. Two hundred and forty-eight volunteers (50-58 years, 55% women) completed a ramp test on a cycle-ergometer. Gas exchange was assessed on a breath-by-breath basis. MCAv was measured via transcranial Doppler and PI calculated. Cardiovascular disease risk (CVR) factors were determined and comprised of measurements of central obesity, blood pressure, fasted plasma glucose, and lipids. The MCAv and PI responses to exercise were compared across body mass index categories, CVR score, and fitness status. We found sex-specific differences in MCAv and PI at rest. However, both sexes showed a similar relative change to baseline (Δ%MCAvmean). Regarding body mass index, obese women (body mass index > 30 kg m-2) had lower MCAv and Δ%MCAvmean and higher PI compared with normo-weight women during exercise. Apart, women with a 0 CVR score showed higher MCAv and lower PI during exercise than those with a score of +3 CVR. Differences between low and high CVR during exercise in Δ%MCAvmean were also found. Eventually, low fitness showed diminished MCAv and a lower response to exercise than high fitness. This study has highlighted significant variability in MCAv responsiveness to exercise among middle-aged adults. Body composition, CVR, and fitness status may play a significant role in preserving cerebrovascular health. These findings shed light on the importance of understanding the cerebrovascular response to exercise.

The therapeutic role of exercise training during menopause for reducing vascular disease

Menopause marks a major milestone in female reproductive ageing. It is characterized by the cessation of ovarian function and a concomitant decline in hormones such as oestradiol. Subsequently, females undergoing menopausal transition experience a progressive increase in cardiovascular and cerebrovascular disease risk. During menopause, reductions in nitric oxide (NO) bioavailability, endothelial dysfunction, increases in systemic inflammation, oxidative stress, and impaired vascular remodelling may contribute towards an accelerated decline in the function of cerebral and peripheral vascular systems. Historically, hormone therapy (HT) has been used as a means of managing vascular disease risk and reducing menopause-associated vasomotor symptoms such as hot flushes, though some studies suggest regular exercise has the potential to be a promising alternative. Regular aerobic exercise during early postmenopause may slow vascular decline by improving NO and oestradiol bioavailability, promoting positive vascular remodelling and lowering systemic inflammation. However, exercise-mediated improvements in markers of vascular function are not consistently observed in oestradiol-deficient postmenopausal women. Emerging evidence suggests that due to the greater oestradiol bioavailability during early postmenopause, vascular adaptations to exercise may be enhanced during this stage, as opposed to late postmenopause. Subsequently it may be important to begin regular exercise in the years preceding and immediately following the final menstrual period to slow the progression of vascular disease risk during perimenopause and beyond. The present review will provide a summary of our current understanding of how vascular function is affected during menopause and the role of regular aerobic and resistance exercise training in managing vascular disease risk.

Effect of moderate-intensity aquatic treadmill exercise on cognitive function and cerebral blood flow for healthy older adults

To compare the effect of moderate-intensity aquatic treadmill exercise (ATM) on cerebral blood flow (CBF) and cognitive function in healthy older adults to that of moderate-intensity land-based treadmill exercise (LTM). This randomized controlled trial study was conducted between May 2023 and Oct 2023. Twenty-eight participants aged 60-80 were randomly assigned to either ATM group (N = 14) or LTM group (N = 14). Cognitive function and cerebral blood flow were assessed before and after the exercise. The outcome measures used in this study were the Digit Symbol Substitution Test (DSST) and the Digit Span Test (DST) to assess cognitive performance, and the mean middle cerebral artery blood velocity (MCAvmean) to evaluate CBF. A mixed effects model was used to analyze the within-group and between-group differences in cognitive function and CBF outcomes pre-to-post treadmill by SPSS. The DSST demonstrated a statistically significant improvement within both the ATM [β ± SE: -13.643 ± 2.407, 95 % CI: -18.749, -8.537] and LTM [β ± SE: -19.25 ± 3.66, 95 % CI: -26.424, -12.076] groups, indicating clinical significance in both groups. Both ATM and LTM groups exhibited post-exercise improvements within their respective groups for forward Digit Span Test (FDST) [ATM β ± SE: -0.143 ± 0.362, 95 % CI: -0.92, 0.634; LTM β ± SE: -0.286 ± 0.37, 95 % CI: -1.078, 0.506] and backward Digit Span Test (BDST) (ATM β ± SE: -1.741 ± 5.377, 95 % CI: -13.27, 9.792; LTM β ± SE: -6.729 ± 5.370, 95 % CI: -4.788, 18.24). In terms of MCAvmean, there is a higher improvement of CBF in ATM group [β ± SE: -138.669 ± 67.9217, 95 % CI: -288.164, 10.826] than LTM group [β ± SE: -9.305 ± 70.076, 95 % CI: -153.617, 135.007]. Hence, a single bout of moderate-intensity ATM and LTM can enhance cognitive function and CBF in healthy older adults, suggesting their potential as preventive strategies against age-related declines.

Tissue clearing and three-dimensional imaging of intact tissues: a review on FACT protocol

FACT is a developed technique for clearing tissues that does not use acrylamide. Since the removal of lipids is crucial for transparency and efficient antibody staining throughout the tissue, especially for microscopy and imaging, it is a harmful process that can cause the loss of important biological molecules such as proteins. The FACT technique overcomes this by chemically bonding the membrane and intracellular proteins with the extracellular matrix, creating a massive 3D hydrogel matrix and providing structural support to fortify the tissue during processing. Compared to other acrylamide-based techniques, the FACT technique requires less labor and harmful chemicals and is therefore considered a more suitable option. In this study, we describe the complete FACT protocol for antibody staining and imaging of whole-cleared tissues while preserving structure and improving image quality. The protocol includes tissue perfusion, fixation, clearing, antibody staining, refractive index matching (RIM) (), microscopy, and imaging. The timing for each step varies depending on the size, weight, and type of tissue, as well as the type of immunostaining. We provide an example of the FACT protocol using mouse brain tissue, which demonstrates its suitability for molecular interrogation analysis of large tissues. The FACT technique has been successfully performed on different types of tissues, making it a favorable choice for a variety of applications.

Unlocking potential of oxytocin: improving intracranial lymphatic drainage for Alzheimer's disease treatment

Background: The impediment to β-amyloid (Aβ) clearance caused by the invalid intracranial lymphatic drainage in Alzheimer's disease is pivotal to its pathogenesis, and finding reliable clinical available solutions to address this challenge remains elusive. Methods: The potential role and underlying mechanisms of intranasal oxytocin administration, an approved clinical intervention, in improving intracranial lymphatic drainage in middle-old-aged APP/PS1 mice were investigated by live mouse imaging, ASL/CEST-MRI scanning, in vivo two-photon imaging, immunofluorescence staining, ELISA, RT-qPCR, Western blotting, RNA-seq analysis, and cognitive behavioral tests. Results: Benefiting from multifaceted modulation of cerebral hemodynamics, aquaporin-4 polarization, meningeal lymphangiogenesis and transcriptional profiles, oxytocin administration normalized the structure and function of both the glymphatic and meningeal lymphatic systems severely impaired in middle-old-aged APP/PS1 mice. Consequently, this intervention facilitated the efficient drainage of Aβ from the brain parenchyma to the cerebrospinal fluid and then to the deep cervical lymph nodes for efficient clearance, as well as improvements in cognitive deficits. Conclusion: This work broadens the underlying neuroprotective mechanisms and clinical applications of oxytocin medication, showcasing its promising therapeutic prospects in central nervous system diseases with intracranial lymphatic dysfunction.

[Neurodevelopment and cerebral blood flow in children aged 2-6 years with autism spectrum disorder]

OBJECTIVES

To investigate the neurodevelopmental characteristics of children with autism spectrum disorder (ASD), analyze the correlation between neurodevelopmental indicators and cerebral blood flow (CBF), and explore the potential mechanisms of neurodevelopment in ASD children.

METHODS

A retrospective study was conducted on 145 children aged 2-6 years with newly-diagnosed ASD. Scores from the Gesell Developmental Diagnosis Scale and the Autism Behavior Checklist (ABC) and CBF results were collected to compare gender differences in the development of children with ASD and analyze the correlation between CBF and neurodevelopmental indicators.

RESULTS

Fine motor and personal-social development quotient in boys with ASD were lower than those in girls with ASD (P<0.05). Gross motor development quotient in ASD children was negatively correlated with CBF in the left frontal lobe (r=-0.200, P=0.016), right frontal lobe (r=-0.279, P=0.001), left parietal lobe (r=-0.208, P=0.012), and right parietal lobe (r=-0.187, P=0.025). The total ABC score was positively correlated with CBF in the left amygdala (r=0.295, P<0.001).

CONCLUSIONS

Early intervention training should pay attention to gender and developmental structural characteristics for precise intervention in ASD children. CBF has the potential to become a biological marker for assessing the severity of ASD.

Implication of Hypotension in the Pathogenesis of Cognitive Impairment and Brain Injury in Chronic Liver Disease

The incidence of chronic liver disease is on the rise. One of the primary causes of hospital admissions for patients with cirrhosis is hepatic encephalopathy (HE), a debilitating neurological complication. HE is defined as a reversible syndrome, yet there is growing evidence stating that, under certain conditions, HE is associated with permanent neuronal injury and irreversibility. The pathophysiology of HE primarily implicates a strong role for hyperammonemia, but it is believed other pathogenic factors are involved. The fibrotic scarring of the liver during the progression of chronic liver disease (cirrhosis) consequently leads to increased hepatic resistance and circulatory anomalies characterized by portal hypertension, hyperdynamic circulatory state and systemic hypotension. The possible repercussions of these circulatory anomalies on brain perfusion, including impaired cerebral blood flow (CBF) autoregulation, could be implicated in the development of HE and/or permanent brain injury. Furthermore, hypotensive insults incurring during gastrointestinal bleed, infection, or liver transplantation may also trigger or exacerbate brain dysfunction and cell damage. This review will focus on the role of hypotension in the onset of HE as well as in the occurrence of neuronal cell loss in cirrhosis.

Photobiomodulation in experimental models of Alzheimer's disease: state-of-the-art and translational perspectives

Alzheimer's disease (AD) poses a significant public health problem, affecting millions of people across the world. Despite decades of research into therapeutic strategies for AD, effective prevention or treatment for this devastating disorder remains elusive. In this review, we discuss the potential of photobiomodulation (PBM) for preventing and alleviating AD-associated pathologies, with a focus on the biological mechanisms underlying this therapy. Future research directions and guidance for clinical practice for this non-invasive and non-pharmacological therapy are also highlighted. The available evidence indicates that different treatment paradigms, including transcranial and systemic PBM, along with the recently proposed remote PBM, all could be promising for AD. PBM exerts diverse biological effects, such as enhancing mitochondrial function, mitigating the neuroinflammation caused by activated glial cells, increasing cerebral perfusion, improving glymphatic drainage, regulating the gut microbiome, boosting myokine production, and modulating the immune system. We suggest that PBM may serve as a powerful therapeutic intervention for AD.

Cerebral hemodynamics and cognitive functions in the acute and subacute stage of mild ischemic stroke: a longitudinal pilot study

The association between cerebral hemodynamics and cognitive impairment has been reported in neurodegenerative and cerebrovascular disorders (CVD). However, it is still unclear whether changes occur in the acute phase of CVD. Here we investigated cognitive and hemodynamic parameters and their association in patients with CVD during the acute and subacute phases. Seventy-three patients with mild stroke, not undergoing endovascular treatment, were recruited. All subjects were devoid of intracranial or external carotid stenosis, significant chronic cerebrovascular pathology, dementia or non-compensated cardiovascular diseases. Patients were evaluated within 7 days from symptoms onset (T1) and after 3 months (T2). Clinical and demographic data were collected. NIHSS, MoCA, FAB, and Word-Color Stroop test (WCST) were used to evaluate disease severity and cognitive functions. Basal hemodynamic parameters in the middle cerebral artery were measured with transcranial Doppler. Differences between T2 and T1, correlations between cognitive and hemodynamic variables at T1 and T2, as well as correlations between the T2-T1 variation in cognitive and hemodynamic parameters were assessed. At T1, cognitive performance of MoCA, FAB, and WCST was lower compared with T2; and pulsatility index, a parameter reflecting distal vascular resistance, was higher. However, no correlations between the changes in cognitive and hemodynamic variables were found; therefore, the two seems to be independent phenomena. In the acute phase, the linear association between cerebral blood flow and cognitive performances was lost, probably due to a differential effect of microenvironment changes and vascular-specific phenomena on cognition and cerebral hemodynamics. This relationship was partially restored in the subacute phase.

Effect of lower body negative pressure on cardiac and cerebral function in postural orthostatic tachycardia syndrome: A pilot MRI assessment

Postural orthostatic tachycardia syndrome (POTS) is characterized by an excessive heart rate (HR) response upon standing and symptoms indicative of inadequate cerebral perfusion. We tested the hypothesis that during lower body negative pressure (LBNP), individuals with POTS would have larger decreases in cardiac and cerebrovascular function measured using magnetic resonance (MR) imaging. Eleven patients with POTS and 10 healthy controls were studied at rest and during 20 min of -25 mmHg LBNP. Biventricular volumes, stroke volume (SV), cardiac output (Qc), and HR were determined by cardiac MR. Cerebral oxygen uptake (VO2 ) in the superior sagittal sinus was calculated from cerebral blood flow (CBF; MR phase contrast), venous O2 saturation (SvO2 ; susceptometry-based oximetry), and arterial O2 saturation (pulse oximeter). Regional cerebral perfusion was determined using arterial spin labelling. HR increased in response to LBNP (p < 0.001) with no group differences (HC: +9 ± 8 bpm; POTS: +13 ± 11 bpm; p = 0.35). Biventricular volumes, SV, and Qc decreased during LBNP (p < 0.001). CBF and SvO2 decreased with LBNP (p = 0.01 and 0.03, respectively) but not cerebral VO2 (effect of LBNP: p = 0.28; HC: -0.2 ± 3.7 mL/min; POTS: +1.1 ± 2.0 mL/min; p = 0.33 between groups). Regional cerebral perfusion decreased during LBNP (p < 0.001) but was not different between groups. These data suggest patients with POTS have preserved cardiac and cerebrovascular function.

Cerebral blood flow and white matter alterations in adults with phenylketonuria

BACKGROUND

Phenylketonuria (PKU) represents a congenital metabolic defect that disrupts the process of converting phenylalanine (Phe) into tyrosine. Earlier investigations have revealed diminished cognitive performance and changes in brain structure and function (including the presence of white matter lesions) among individuals affected by PKU. However, there exists limited understanding regarding cerebral blood flow (CBF) and its potential associations with cognition, white matter lesions, and metabolic parameters in patients with PKU, which we therefore aimed to investigate in this study.

METHOD

Arterial spin labeling perfusion MRI was performed to measure CBF in 30 adults with early-treated classical PKU (median age 35.5 years) and 59 healthy controls (median age 30.0 years). For all participants, brain Phe levels were measured with 1H spectroscopy, and white matter lesions were rated by two neuroradiologists on T2 weighted images. White matter integrity was examined with diffusion tensor imaging (DTI). For patients only, concurrent plasma Phe levels were assessed after an overnight fasting period. Furthermore, past Phe levels were collected to estimate historical metabolic control. On the day of the MRI, each participant underwent a cognitive assessment measuring IQ and performance in executive functions, attention, and processing speed.

RESULTS

No significant group difference was observed in global CBF between patients and controls (F (1, 87) = 3.81, p = 0.054). Investigating CBF on the level of cerebral arterial territories, reduced CBF was observed in the left middle and posterior cerebral artery (MCA and PCA), with the most prominent reduction of CBF in the anterior subdivision of the MCA (F (1, 87) = 6.15, p = 0.015, surviving FDR correction). White matter lesions in patients were associated with cerebral blood flow reduction in the affected structure. Particularly, patients with lesions in the occipital lobe showed significant CBF reductions in the left PCA (U = 352, p = 0.013, surviving FDR correction). Additionally, axial diffusivity measured with DTI was positively associated with CBF in the ACA and PCA (surviving FDR correction). Cerebral blood flow did not correlate with cognitive performance or metabolic parameters.

CONCLUSION

The relationship between cerebral blood flow and white matter indicates a complex interplay between vascular health and white matter alterations in patients with PKU. It highlights the importance of considering a multifactorial model when investigating the impact of PKU on the brain.

Dual-color miniscope imaging of microvessels and neuronal activity in the hippocampus CA1 region of freely moving mice following alcohol administration

Moderate-to-heavy episodic ("binge") drinking is the most common form of alcohol consumption in the United States. Alcohol at binge drinking concentrations reduces brain artery diameter in vivo and in vitro in many species including rats, mice, and humans. Despite the critical role played by brain vessels in maintaining neuronal function, there is a shortage of methodologies to simultaneously assess neuron and blood vessel function in deep brain regions. Here, we investigate cerebrovascular responses to ethanol by choosing a deep brain region that is implicated in alcohol disruption of brain function, the hippocampal CA1, and describe the process for obtaining simultaneous imaging of pyramidal neuron activity and diameter of nearby microvessels in freely moving mice via a dual-color miniscope. Recordings of neurovascular events were performed upon intraperitoneal injection of saline versus 3 g/kg ethanol in the same mouse. In male mice, ethanol mildly increased the amplitude of calcium signals while robustly decreasing their frequency. Simultaneously, ethanol decreased microvessel diameter. In females, ethanol did not change the amplitude or frequency of calcium signals from CA1 neurons but decreased microvessel diameter. A linear regression of ethanol-induced reduction in number of active neurons and microvessel constriction revealed a positive correlation (R = 0.981) in females. Together, these data demonstrate the feasibility of simultaneously evaluating neuronal and vascular components of alcohol actions in a deep brain area in freely moving mice, as well as the sexual dimorphism of hippocampal neurovascular responses to alcohol.

Cortical microvascular blood flow velocity mapping by combining dynamic light scattering optical coherence tomography and two-photon microscopy

Significance

The accurate large-scale mapping of cerebral microvascular blood flow velocity is crucial for a better understanding of cerebral blood flow (CBF) regulation. Although optical imaging techniques enable both high-resolution microvascular angiography and fast absolute CBF velocity measurements in the mouse cortex, they usually require different imaging techniques with independent system configurations to maximize their performances. Consequently, it is still a challenge to accurately combine functional and morphological measurements to co-register CBF speed distribution from hundreds of microvessels with high-resolution microvascular angiograms.

Aim

We propose a data acquisition and processing framework to co-register a large set of microvascular blood flow velocity measurements from dynamic light scattering optical coherence tomography (DLS-OCT) with the corresponding microvascular angiogram obtained using two-photon microscopy (2PM).

Approach

We used DLS-OCT to first rapidly acquire a large set of microvascular velocities through a sealed cranial window in mice and then to acquire high-resolution microvascular angiograms using 2PM. The acquired data were processed in three steps: (i) 2PM angiogram coregistration with the DLS-OCT angiogram, (ii) 2PM angiogram segmentation and graphing, and (iii) mapping of the CBF velocities to the graph representation of the 2PM angiogram.

Results

We implemented the developed framework on the three datasets acquired from the mice cortices to facilitate the coregistration of the large sets of DLS-OCT flow velocity measurements with 2PM angiograms. We retrieved the distributions of red blood cell velocities in arterioles, venules, and capillaries as a function of the branching order from precapillary arterioles and postcapillary venules from more than 1000 microvascular segments.

Conclusions

The proposed framework may serve as a useful tool for quantitative analysis of large microvascular datasets obtained by OCT and 2PM in studies involving normal brain functioning, progression of various diseases, and numerical modeling of the oxygen advection and diffusion in the realistic microvascular networks.

The effects and mechanisms of acupuncture for post-stroke cognitive impairment: progress and prospects

Stroke is one of the important causes of both disability and death worldwide, which is very common in older adults. Post-stroke cognitive impairment (PSCI) is a common secondary damage of stroke, which is the main cause of long-term disability and decreased quality of life in stroke patients, which brings a heavy burden to society and families. Acupuncture, as one of the oldest and widely used worldwide techniques in Chinese medicine, is recommended by the World Health Organization (WHO) as an alternative and complementary strategy for improving stroke care. This review comprehensively summarizes literature from the last 25 years, showing that acupuncture can exert strong beneficial effect on PSCI. The mechanisms of acupuncture on PSCI involves anti-neuronal apoptosis, promoting synaptic plasticity, alleviating central and peripheral inflammatory reactions, and regulating brain energy metabolism disorders (including improving cerebral blood flow, glucose utilization and mitochondrial structure and function, etc.), etc. The effects and mechanisms of acupuncture on PSCI reviewed in this study provides scientific and reliable evidence for acupuncture application for PSCI.

A single bout of passive exercise mitigates a mental fatigue-induced inhibitory control deficit

Sustained cognitive effort associated with the psychomotor vigilance task (PVT) increases objective and subjective measures of mental fatigue and elicits a post-PVT inhibitory control deficit. In contrast, passive exercise wherein an individual's limbs are moved via an external force (i.e., mechanically driven cycle ergometer flywheel) provides a postexercise inhibitory control benefit linked to an exercise-based increase in cerebral blood flow. Here, we examined whether passive exercise performed concurrently with the PVT 'blunts' an inhibitory control deficit. On separate days, participants (N = 27) completed a 20 min PVT protocol (control condition) and same duration PVT protocol paired with passive cycle ergometry (passive exercise condition). Prior to (i.e., baseline), immediately after and 30 min after each condition inhibitory control was assessed via the antisaccade task. Antisaccades require a goal-directed eye movement (i.e., saccade) mirror-symmetrical to a target and provide an ideal tool for evaluating task-based changes in inhibitory control. PVT results showed that vigilance (as assessed via reaction time: RT) during control and passive exercise conditions decreased from the first to last 5 min of the protocol and increased subjective ratings of mental fatigue. As well, in the control condition, immediate (but not 30-min) post-intervention antisaccade RTs were longer than their baseline counterparts-a result evincing a transient mental fatigue-based inhibitory control deficit. For the passive exercise condition, immediate and 30-min post-intervention antisaccade RTs were shorter than their baseline counterparts and this result was linked to decreased subjective ratings of mental fatigue. Thus, passive exercise ameliorated the selective inhibitory control deficit associated with PVT-induced mental fatigue and thus provides a potential framework to reduce executive dysfunction in vigilance-demanding occupations.

Water intake, hydration status and 2-year changes in cognitive performance: a prospective cohort study

BACKGROUND

Water intake and hydration status have been suggested to impact cognition; however, longitudinal evidence is limited and often inconsistent. This study aimed to longitudinally assess the association between hydration status and water intake based on current recommendations, with changes in cognition in an older Spanish population at high cardiovascular disease risk.

METHODS

A prospective analysis was conducted of a cohort of 1957 adults (aged 55-75) with overweight/obesity (BMI between ≥ 27 and < 40 kg/m2) and metabolic syndrome from the PREDIMED-Plus study. Participants had completed bloodwork and validated, semiquantitative beverage and food frequency questionnaires at baseline, as well as an extensive neuropsychological battery of 8 validated tests at baseline and 2 years of follow-up. Hydration status was determined by serum osmolarity calculation and categorized as < 295 mmol/L (hydrated), 295-299.9 mmol/L (impending dehydration), and ≥ 300 mmol/L (dehydrated). Water intake was assessed as total drinking water intake and total water intake from food and beverages and according to EFSA recommendations. Global cognitive function was determined as a composite z-score summarizing individual participant results from all neuropsychological tests. Multivariable linear regression models were fitted to assess the associations between baseline hydration status and fluid intake, continuously and categorically, with 2-year changes in cognitive performance.

RESULTS

The mean baseline daily total water intake was 2871 ± 676 mL/day (2889 ± 677 mL/day in men; 2854 ± 674 mL/day in women), and 80.2% of participants met the ESFA reference values for an adequate intake. Serum osmolarity (mean 298 ± 24 mmol/L, range 263 to 347 mmol/L) indicated that 56% of participants were physiologically dehydrated. Lower physiological hydration status (i.e., greater serum osmolarity) was associated with a greater decline in global cognitive function z-score over a 2-year period (β: - 0.010; 95% CI - 0.017 to - 0.004, p-value = 0.002). No significant associations were observed between water intake from beverages and/or foods with 2-year changes in global cognitive function.

CONCLUSIONS

Reduced physiological hydration status was associated with greater reductions in global cognitive function over a 2-year period in older adults with metabolic syndrome and overweight or obesity. Future research assessing the impact of hydration on cognitive performance over a longer duration is needed.

TRIAL REGISTRATION

International Standard Randomized Controlled Trial Registry, ISRCTN89898870. Retrospectively registered on 24 July 2014.

Recent advances in arterial spin labeling perfusion MRI in patients with vascular cognitive impairment

Cognitive impairment (CI) is a major health concern in aging populations. It impairs patients' independent life and may progress to dementia. Vascular cognitive impairment (VCI) encompasses all cerebrovascular pathologies that contribute to cognitive impairment (CI). Moreover, the majority of CI subtypes involve various aspects of vascular dysfunction. Recent research highlights the critical role of reduced cerebral blood flow (CBF) in the progress of VCI, and the detection of altered CBF may help to detect or even predict the onset of VCI. Arterial spin labeling (ASL) is a non-invasive, non-ionizing perfusion MRI technique for assessing CBF qualitatively and quantitatively. Recent methodological advances enabling improved signal-to-noise ratio (SNR) and data acquisition have led to an increase in the use of ASL to assess CBF in VCI patients. Combined with other imaging modalities and biomarkers, ASL has great potential for identifying early VCI and guiding prediction and prevention strategies. This review focuses on recent advances in ASL-based perfusion MRI for identifying patients at high risk of VCI.

Effect of simultaneous exercise and cognitive training on executive functions, baroreflex sensitivity, and pre-frontal cortex oxygenation in healthy older adults: a pilot study

Aging is characterized by cognitive decline affecting daily functioning. To manage this socio-economic challenge, several non-pharmacological methods such as physical, cognitive, and combined training are proposed. Although there is an important interest in this subject, the literature is still heterogeneous. The superiority of simultaneous training compared to passive control and physical training alone seems clear but very few studies compared simultaneous training to cognitive training alone. The aim of this pilot study was to investigate the effect of simultaneous exercise and cognitive training on several cognitive domains in healthy older adults, in comparison with either training alone. Thirty-five healthy older adults were randomized into one of three experimental groups: exercise training, cognitive training, and simultaneous exercise and cognitive training. The protocol involved two 30-min sessions per week for 24 weeks. Cognitive performance in several domains, pre-frontal cortex oxygenation, and baroreflex sensitivity were assessed before and after the intervention. All groups improved executive performance, including flexibility or working memory. We found a group by time interaction for inhibition cost (F(2,28) = 6.44; p < 0.01) and baroreflex sensitivity during controlled breathing (F(2,25) = 4.22; p = 0.01), the magnitude of improvement of each variable being associated (r = -0.39; p = 0.03). We also found a decrease in left and right pre-frontal cortex oxygenation in all groups during the trail making test B. A simultaneous exercise and cognitive training are more efficient than either training alone to improve executive function and baroreflex sensitivity. The results of this study may have important clinical repercussions by allowing to optimize the interventions designed to maintain the physical and cognitive health of older adults.

Factors influencing functional near-infrared spectroscopy in postpartum depression: A cross-sectional study

OBJECTIVE

To explore whether functional near-infrared spectroscopy (fNIRS) can aid in the early detection and diagnosis of postpartum depression.

METHODS

The study was a cross-sectional survey that invited all women who sought postpartum health examination 42 days after childbirth between August 2020 and January 2021. Personal information, Edinburgh Postnatal Depression Scale (EPDS), and well as fNIRS results were collected.

RESULTS

In all, 109 individuals agreed to participate and completed the examination in its entirety. The variance in integral and centroid values was not statistically significant across different subgroups of depression (P > 0.05). The difference in diagnosis of postpartum major depression between EPDS and fNIRS was statistically significant (P < 0.001). fNIRS results in postpartum depression diagnosis were substantially associated with gestational diabetes mellitus (P = 0.027), the number of pregnancies (P = 0.001), and postpartum body mass index (P = 0.035).

CONCLUSION

fNIRS can provide an objective method for early detection and diagnosis of postpartum depression. Certain clinical conditions can have an effect on brain activity, which may result in postpartum depression. Additional high-quality study is required to establish strong evidence on the subject.

Effects of chronic consumption of specific fruit (berries, cherries and citrus) on cognitive health: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVES

The cognitive-protective effects related to the consumption of a variety of fruits are supported by several intervention studies. This systematic review and meta-analysis compared the magnitude of effects following chronic (≥1 week) consumption of frozen, freeze-dried powder including extracts and juices of fruits, covering berries, cherries and citrus, on cognition and mood in adults.

METHODS

PubMed, Web of Science, Scopus, and psycARTICLES were searched from inception until February, 2021. Inclusion criteria were randomised controlled trials assessing memory, executive function, psychomotor speed, mood and mini mental state examination in adult participants ≥18 years of age. Cognition was tested by global or domain specific tasks.

RESULTS

Out of 13,861 articles identified, 16 papers were included; 11 studies provided suitable data for meta-analysis. Fourteen studies reported improvement or trend for improvement in cognition, five studies assessed mood and one study supplementing grape juice found trend for mood improvement. From the meta-analysis, cherry juice supplementation was suggested to improve psychomotor speed by -0.37 of standardised mean difference (95% CI [-0.74, 0.01]) in reaction time (P = 0.05).

CONCLUSIONS

The meta-analysis did not sufficiently support a role for fruits or fruit forms to improve cognition and mood.

Intense long-term training impairs brain health compared with moderate exercise: Experimental evidence and mechanisms

The consequences of extremely intense long-term exercise for brain health remain unknown. We studied the effects of strenuous exercise on brain structure and function, its dose-response relationship, and mechanisms in a rat model of endurance training. Five-week-old male Wistar rats were assigned to moderate (MOD) or intense (INT) exercise or a sedentary (SED) group for 16 weeks. MOD rats showed the highest motivation and learning capacity in operant conditioning experiments; SED and INT presented similar results. In vivo MRI demonstrated enhanced global and regional connectivity efficiency and clustering as well as a higher cerebral blood flow (CBF) in MOD but not INT rats compared with SED. In the cortex, downregulation of oxidative phosphorylation complex IV and AMPK activation denoted mitochondrial dysfunction in INT rats. An imbalance in cortical antioxidant capacity was found between MOD and INT rats. The MOD group showed the lowest hippocampal brain-derived neurotrophic factor levels. The mRNA and protein levels of inflammatory markers were similar in all groups. In conclusion, strenuous long-term exercise yields a lesser improvement in learning ability than moderate exercise. Blunting of MOD-induced improvements in CBF and connectivity efficiency, accompanied by impaired mitochondrial energetics and, possibly, transient local oxidative stress, may underlie the findings in intensively trained rats.

Cerebral Blood Flow in Predator Stress-Resilient and -Susceptible Rats and Mechanisms of Resilience

Stress-induced conditions are associated with impaired cerebral blood flow (CBF) and increased risk of dementia and stroke. However, these conditions do not develop in resilient humans and animals. Here the effects of predator stress (PS, cat urine scent, ten days) on CBF and mechanisms of CBF regulation were compared in PS-susceptible (PSs) and PS-resilient (PSr) rats. Fourteen days post-stress, the rats were segregated into PSs and PSr groups based on a behavior-related anxiety index (AI). CBF and its endothelium-dependent changes were measured in the parietal cortex by laser Doppler flowmetry. The major findings are: (1) PS susceptibility was associated with reduced basal CBF and endothelial dysfunction. In PSr rats, the basal CBF was higher, and endothelial dysfunction was attenuated. (2) CBF was inversely correlated with the AI of PS-exposed rats. (3) Endothelial dysfunction was associated with a decrease in eNOS mRNA in PSs rats compared to the PSr and control rats. (4) Brain dopamine was reduced in PSs rats and increased in PSr rats. (5) Plasma corticosterone of PSs was reduced compared to PSr and control rats. (6) A hypercoagulation state was present in PSs rats but not in PSr rats. Thus, potential stress resilience mechanisms that are protective for CBF were identified.

Efficacy and safety of 3-n-butylphthalide for the treatment of cognitive impairment: A systematic review and meta-analysis

BACKGROUND

Current evidence for the efficacy of pharmacological treatment in improving cognitive function is absent. Recent studies have reported that 3-n-butylphthalide (NBP) has a positive effect on improving cognitive impairment; however, its clinical efficacy and safety is unclear. Therefore, we conducted a meta-analysis to assess its efficacy and safety for cognitive impairment.

METHODS

We systematically searched the PubMed, EMBASE, Cochrane Library, Web of Science, and Scopus databases, and two reviewers independently screened and extracted the data from included studies. We synthesized the data using the Review Manager Software version 5.3.

RESULTS

We included six randomized clinical trials (RCTs), encompassing 851 patients with cognitive impairment. The results showed that NBP improved cognitive impairment. Specifically, the clinical efficacy was better than that in the control group, with better performance in improving the Mini-Mental State Examination and the Montreal Cognitive Assessment scores, while decreasing the Alzheimer's Disease Assessment Scale-Cognitive subscale and the Clinician's Interview-Based Impression of Change plus caregiver input scores. There was no significant difference in the incidence of adverse events between both groups.

CONCLUSION

The NBP is effective and safe in improving cognitive impairment; however, more high-quality RCTs are needed to confirm these findings.

A Bibliometric and Visual Analysis of Exercise Intervention Publications for Alzheimer’s Disease (1998–2021)

Alzheimer’s disease (AD) is the most common cause of dementia worldwide, posing a considerable economic burden to patients and society as a whole. Exercise has been confirmed as a non-drug intervention method in the related literature on AD. However, at present, there are still few bibliometric studies on AD exercise research. In order to fill the gap, this paper aims to intuitively analyze the growth in AD exercise literature published from 1998 to 2021 using bibliometrics, providing historical insights for scientific research circles. The main source of literature retrieval is the Web of Science database. Using the Boolean operator tools “OR” and “AND” combined with keywords related to “exercise” and “Alzheimer’s disease”, we conducted a title search and obtained 247 documents. Using Microsoft Excel, Datawrapper, and Biblioshiny, this study carried out a bibliometric analysis of countries, institutions, categories, journals, documents, authors, and keyword plus terms. The study found that the number of papers published from 2016 to 2021 had the greatest increase, which may have been influenced by the Global Dementia Report 2015 and COVID-19. Interdisciplinary cooperation and the research results published in high-scoring journals actively promoted research and development in the AD exercise field. The United States and the University of Minnesota system play a central role in this field. In future, it will be necessary to explore the effectiveness and feasibility of multi-mode interventions on an active lifestyle, including exercise, in different groups and environments worldwide. This study may provide a direction and path for future research by showing the global overview, theme evolution, and future trends of research results in the AD exercise field.

Cognitive decline in heart failure: Biomolecular mechanisms and benefits of exercise

By definition, heart failure (HF) is a human pathological condition affecting the structure and function of all organs in the body, and the brain is not an exception to that. Failure of the heart to pump enough blood centrally and peripherally is at the foundation of HF patients' inability to attend even the most ordinary daily activities and progressive deterioration of their cognitive capacity. What is more, between heart and brain exists a bidirectional relationship that goes well beyond hemodynamics and concerns bioelectric and endocrine signaling. This increasingly consolidated evidence makes the scenario even more complex. Studies have mainly chased how HF impairs cognition without focusing much on preventive measures, notably cardio-cerebral health proxies. Here, we aim to provide a brief account of known and hypothetical factors that may explain how exercise can help obviate cognitive dysfunction associated with HF in its different forms. As we shall see, there is a stringent need for a deeper grasp of such mechanisms. Indeed, gaining this new knowledge will automatically shed new light on the inner workings of HF itself, thus resulting in more effective prevention and treatment of this escalating syndrome.

Dementia risk and dynamic response to exercise: A non-randomized clinical trial

Background

Physical exercise may support brain health and cognition over the course of typical aging. The goal of this nonrandomized clinical trial was to examine the effect of an acute bout of aerobic exercise on brain blood flow and blood neurotrophic factors associated with exercise response and brain function in older adults with and without possession of the Apolipoprotein epsilon 4 (APOE4) allele, a genetic risk factor for developing Alzheimer’s. We hypothesized that older adult APOE4 carriers would have lower cerebral blood flow regulation and would demonstrate blunted neurotrophic response to exercise compared to noncarriers.

Methods

Sixty-two older adults (73±5 years old, 41 female [67%]) consented to this prospectively enrolling clinical trial, utilizing a single arm, single visit, experimental design, with post-hoc assessment of difference in outcomes based on APOE4 carriership. All participants completed a single 15-minute bout of moderate-intensity aerobic exercise. The primary outcome measure was change in cortical gray matter cerebral blood flow in cortical gray matter measured by magnetic resonance imaging (MRI) arterial spin labeling (ASL), defined as the total perfusion (area under the curve, AUC) following exercise. Secondary outcomes were changes in blood neurotrophin concentrations of insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), and brain derived neurotrophic factor (BDNF).

Results

Genotyping failed in one individual (n = 23 APOE4 carriers and n = 38 APOE4 non-carriers) and two participants could not complete primary outcome testing. Cerebral blood flow AUC increased immediately following exercise, regardless of APOE4 carrier status. In an exploratory regional analyses, we found that cerebral blood flow increased in hippocampal brain regions, while showing no change in cerebellum across both groups. Among high inter-individual variability, there were no significant changes in any of the 3 neurotrophic factors for either group immediately following exercise.

Conclusions

Our findings show that both APOE4 carriers and non-carriers show similar effects of exercise-induced increases in cerebral blood flow and neurotrophic response to acute aerobic exercise. Our results provide further evidence that acute exercise-induced increases in cerebral blood flow may be regional specific, and that exercise-induced neurotrophin release may show a differential effect in the aging cardiovascular system. Results from this study provide an initial characterization of the acute brain blood flow and neurotrophin responses to a bout of exercise in older adults with and without this known risk allele for cardiovascular disease and Alzheimer’s disease.

Trial registration

Dementia Risk and Dynamic Response to Exercise (DYNAMIC); Identifier: NCT04009629.

Effect of macular pigment carotenoids on cognitive functions: A systematic review

Lutein and zeaxanthin-xanthophyll carotenoids with antioxidant and anti-inflammatory characteristics-are present in the retina and the brain. High concentrations of these carotenoids have been positively related to cognitive performance. Therefore, this systematic review analyses the relationship between macular pigment density and cognitive functions. Most relevant databases were scoured for studies on healthy people relating cognitive functions to macular pigment optical density (MPOD). There were no age, sex, or race limitations. PROSPERO registration: CRD42021254833. Nineteen studies were included, seven randomized controlled trials (RCT) and eleven observational studies. The general aim of the studies was to examine the association between carotenoids (lutein, meso‑zeaxanthin and zeaxanthin) and cognitive function. Most observational studies correlates MPOD levels with cognitive function or brain activity. Besides, RCTs compared the cognitive function and/or brain activity after increasing lutein and zeaxanthin intake though dietary supplementation or avocado consumption. Dietary lutein and zeaxanthin intake increased MPOD in six of the seven clinical trials and significantly improved most of the cognitive functions studied. A wide variety of test and methodologies for measuring cognitive functions were observed. Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults. Brain activity also was related to MPOD, but the results were inconsistent. Only four of the eleven observational studies were based on young people and all studies showed a significant relationship between MPOD and cognitive functions. This systematic review showed a direct relationship among cognitive functions, macular pigment and the intake of lutein and zeaxanthin.

The Relationship Between Resting Cerebral Blood Flow, Neurometabolites, Cardio-Respiratory Fitness and Aging-Related Cognitive Decline

Older adults typically experience a decline in cognitive function, but improvements in physical health and lifestyle can be neuroprotective across the human lifespan. The primary objective of this study is to advance our basic understanding of how cardiorespiratory fitness and neurophysiological attributes relate to cognitive decline. While cerebral blood flow (CBF) is critical for the supply of nutrients to the tissue, the brain's major neurotransmitters (i.e., gamma-aminobutyric acid, GABA, and glutamate-glutamine complex, Glx) are closely linked to oxidative metabolism. Within the context of flow-metabolism coupling, the critical question is how these neurophysiological parameters interplay, resulting in cognitive decline. Further, how cardiorespiratory fitness may impact aging neurophysiology and cognition is not well understood. To address these questions, we recruited 10 younger and 12 older cognitively intact participants to collect GABA and Glx using magnetic resonance spectroscopy (MRS), CBF using pseudo-continuous arterial spin labeling Magnetic Resonance Imaging (MRI), VO2max as a measure of cardiorespiratory fitness using the YMCA submax test, and cognitive and motor-cognitive measures using a battery of behavioral assessments. We observed expected differences in GABA+, Glx, and CBF between younger and older participants in pre-SMA, a frontal domain-general region. When GABA+ and Glx were related to CBF via multiple linear regression, Glx was identified as the main contributor to the model. For higher-order executive function (i.e., inhibition versus color naming), GABA*Glx*CBF interaction was critical in younger, while only Glx was involved in older participants. For unimanual motor dexterity, GABA*Glx interaction was the common denominator across both groups, but younger participants' brain also engages CBF. In terms of selective motor inhibition, CBF from younger participants was the only major neurophysiological factor. In terms of fitness, cardiorespiratory fitness was significantly related to GABA, Glx, and motor performance when combining cohorts, but no group-specific relationships were observed. Taken together, our results indicate that Glx and CBF coupling decreases with aging, perhaps due to altered glial oxidative metabolism. Our data suggest that GABA, Glx, and CBF are engaged and weighted differently for different cognitive measures sensitized to aging, and higher fitness allows for a more efficient metabolic shift that facilitates improved performance on cognitive-motor tasks.

Propionate ameliorates diabetes-induced neurological dysfunction through regulating the PI3K/Akt/eNOS signaling pathway

A large body of research has established diabetes-related cognitive deterioration, sometimes known as "diabetic encephalopathy". Current evidence supports that oxidative stress, neuronal apoptosis, and cerebral microcirculation weakness are associated with cognition deficits induced by diabetes. The present study explores the effect of propionate on neurological deficits, cerebral blood flow, and oxidative stress in diabetic mice. Propionate in different doses (37.5, 75 and 150 mg/kg) was orally administrated daily. Here, we show that propionate can markedly improve neurological function, which is correlated with its capabilities of stimulating nitrogen monoxide (NO) production, increasing cerebral microcirculation, suppressing oxidative stress, and reducing neuron loss in the hippocampus. In addition, the results of Western Blotting indicated that the brain-protective function of propionate in streptozocin (STZ)-induced type 1 diabetes mellitus (T1DM) mice is related to phosphoinositide 3-kinase (PI3K)/serine-threonine protein kinase (Akt)/endothelial nitrogen monoxide synthase (eNOS) signaling pathway. In a diabetic mouse model, propionate reduces cerebral microcirculation, hippocampus apoptosis, and neurological impairment. Thus, propionate, now employed as a food preservative, may also help slow diabetes-induced cognitive loss.

Cognition impairment of rat in undersea environment

This study was designed to examine the cognitive responses of rat simulation model of the undersea environment. Rats were randomized into five groups: control, restraint, hyperbaric air, restraint with hyperbaric air, and restraint with hyperbaric air and immersion The cognition functions were assessed by Morris water maze test and forced swimming test. The cerebral blood flow (CBF) was monitored. The parameters examined were total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-px), glutathione (GSH), glutathione reductase (GR), and malondialdehyde (MDA). It was observed that the rats in the experimental groups had impaired learning and memory and behavioral despair accompanied by increase in CBF and MDA levels but decrease of TAC, SOD, CAT, GSH-px, GSH, and GR levels. These indicated that the simulated underwater conditions might cause immediate and transient cognition impairment in the rat models. The simulated environment induced oxidative stress led to the negative cognitive changes.

Transcranial Doppler studies in Type 2 diabetes mellitus: A systematic review

BACKGROUND

Type II Diabetes mellitus (T2DM) patients are at the risk of developing cerebrovascular diseases, often contributed by altered cerebral haemodynamics. We present a systematic review of studies on cerebral haemodynamics assessment using transcranial Doppler (TCD) in T2DM.

REVIEW METHOD

A systematic review of the published articles in the English language between 1991 to 2021.

DATA SOURCES

Articles were retrieved via Pubmed and Cochrane library. We included Cross-sectional, prospective, retrospective, randomized controlled, and cross-over studies for this review.

RESULTS

A total of 25 articles met the inclusion criteria, which provided data for 3212 patients.

CONCLUSION

Cerebral autoregulation is often impaired among patients with T2DM. The risk increased with the duration of T2DM, related complications and presence of comorbidities.

The relationship between cardiovascular risk and lifestyle activities on hippocampal volumes in normative aging

Background

Despite the life-course perspective of popular aging models, few studies on healthy aging to date have examined both younger and older adulthood. The current study examined how cumulative vascular risk factors and self-reported levels of physical, social, and cognitive activity are associated with differences in hippocampal volumes in healthy younger and older adults.

Methods

34 neurologically healthy participants were separated into two age cohorts: a younger adult group (age 25-35, n = 17) and an older adult group (age 65-82, n = 17). Participants underwent a 3 T T1 MRI and completed a series of questionnaires. Voxel-based morphometry examined whole-brain grey matter density differences between groups. Hippocampal volumes were computed. Analyses examined the association between hippocampal volumes, cumulative vascular risk, and self-reported levels of physical, social, and cognitive activity, both within and across groups.

Results

Between-group comparisons revealed greater cortical atrophy in older relative to young adults in regions including the left and right hippocampus and temporal fusiform cortex. Across-group analyses revealed a significant negative association between cardiovascular risk scores and bilateral hippocampal volumes across age groups. A significant negative association was identified between frequency of social activities and bilateral hippocampal volumes in older adults only. No significant associations were found between left or right hippocampal volumes and total, cognitive, or physical activities in both within- and across-group analyses.

Conclusion

Greater cumulative vascular risk is associated with smaller hippocampal volumes across age cohorts. Findings suggest that social activities with low cognitive load may not be beneficial to structural brain outcomes in older age.

Effect of Paprika Xanthophyll Supplementation on Cognitive Improvement in a Multitasking Exercise: A Pilot Study for Middle-Aged and Older Adults

Ingestion of paprika xanthophyll supplement (PX), which has antioxidant effects, has been recently reported to maintain red blood cell deformability and improve oxygen delivery efficiency. Therefore, we hypothesized that the brain activation induced by multitasking exercise in middle-aged and older participants along with the improved erythrocyte oxygen-carrying efficiency induced by PX supplementation would show a synergistic effect, increasing oxygen supply to the brain and improving cognitive function more effectively. In study 1, cerebral blood flow measurements were conducted during the multitasking exercise and cognitive function tests to verify their effect on cognitive function. The results confirmed that cerebral blood flow increased during the exercise and cognitive function improved after the exercise. In study 2, we compared the effects of the multitasking exercise on cognitive function before and after PX supplementation in middle-aged and older participants to evaluate the effects of PX supplementation. The results suggested that PX supplementation enhanced the effects of active multitasking exercise on cognitive function. We speculate that the improvement of oxygen transport efficiency by PX resulted in more effective oxygen supply, allowing the multitasking exercise to occur more effectively, which was reflected as an improvement in the cognitive function.

Possible effects of short rest after lunch on hemodynamics in the afternoon

PURPOSE

Drowsiness is often experienced in the afternoon after lunch. Decreases in blood flow to the brain secondary to increases in blood flow to the digestive organs after food intake could represent an underlying cause. As various beneficial effects of short rests on mental activities have been reported, the present study investigated hemodynamics using Doppler sonography of the common carotid artery (CCA) and superior mesenteric artery (SMA) after lunch, comparing resting and non-resting cases.

METHODS

Subjects comprised 24 healthy young adults (10 men, 14 women; mean age 22 ± 1 years). Sonography was performed to measure blood flow before and after lunch on each day, with and without a 15-min lying rest with eyes closed after lunch in each subject.

RESULTS

The timing of the peak velocity-time integral in the SMA in resting cases was delayed to 1.5 h after lunch compared to 0.5 h in non-resting cases. Although end-diastolic velocity in the CCA decreased after lunch, this decrease was suppressed in resting cases compared to non-resting cases even 4.5 h after lunch (median 96%, interquartile range [IQR] 83-102% vs. median 87%, IQR 77-92%; P = 0.037). Mean velocity (MV) in the CCA maintained unchanged after lunch in resting cases (P = 0.318), whereas non-resting cases showed decreased MV after lunch (P < 0.001).

CONCLUSION

These findings suggest that a short lying rest with eyes closed suppresses increases in blood flow to the digestive organ and maintains blood flow to the brain after lunch. These hemodynamic changes might help explain the benefits of afternoon rests.

Effect of Exercise on Brain Health: The Potential Role of Lactate as a Myokine

It has been well established in epidemiological studies and randomized controlled trials that habitual exercise is beneficial for brain health, such as cognition and mental health. Generally, it may be reasonable to say that the physiological benefits of acute exercise can prevent brain disorders in late life if such exercise is habitually/chronically conducted. However, the mechanisms of improvement in brain function via chronic exercise remain incompletely understood because such mechanisms are assumed to be multifactorial, such as the adaptation of repeated acute exercise. This review postulates that cerebral metabolism may be an important physiological factor that determines brain function. Among metabolites, the provision of lactate to meet elevated neural activity and regulate the cerebrovascular system and redox states in response to exercise may be responsible for exercise-enhanced brain health. Here, we summarize the current knowledge regarding the influence of exercise on brain health, particularly cognitive performance, with the underlying mechanisms by means of lactate. Regarding the influence of chronic exercise on brain function, the relevance of exercise intensity and modality, particularly high-intensity interval exercise, is acknowledged to induce “metabolic myokine” (i.e., lactate) for brain health.

Are acute sitting-induced changes in inflammation and cerebrovascular function related to impaired mood and cognition?

Purpose

Sedentary behaviour is negatively associated with mood and cognition, yet how acute sitting contributes to these overall associations is unknown. Since sitting heightens inflammation and impairs cerebrovascular function, this study investigated the hypothesis that these sitting-induced changes are related to impaired mood and cognition.

Methods

Twenty-five healthy desk workers (18 male, 28.3 ± 7.5 years, BMI: 24.2 ± 3.3 kg∙m^-2) were recruited. During laboratory visit one, participants were familiarised with cognitive performance tests measuring executive function, attention and working memory. During laboratory visit two, participants completed 6 h of continuous, uninterrupted sitting. At baseline and after 6 h, serum markers of inflammation, middle cerebral artery blood flow velocity (MCAv), cerebrovascular carbon dioxide reactivity (CVR), dynamic cerebral autoregulation (CA), cognitive performance and mood (positive and negative affect, alert, contented and calm) were assessed. Data were analysed using paired-samples t tests and correlation analyses.

Results

Following sitting, C-reactive protein (∆-1.0 µg/ml) and tissue plasminogen activator (∆-360.4 pg/ml) decreased (p < 0.05), MCAv reduced (∆-2.9 cm∙s^-1, p = 0.012) and normalised gain increased in the very low frequency range, indicating impaired CA (∆ + 0.22%·mmHg^-1, p = 0.016). Positive affect (∆-4.6, p < 0.001), and alert (∆-10.6 p = 0.002) and contented (∆-7.4, p = 0.006) mood states also decreased following sitting. No significant changes in interleukin-6, tumour necrosis factor-alpha, von Willebrand factor, CVR or cognitive performance were observed (p > 0.05). The observed changes in inflammation and cerebrovascular function were not related to changes in mood (p > 0.05).

Conclusion

Alterations in inflammation or cerebrovascular function following six hours of prolonged, uninterrupted sitting are not related to the observed reductions in mood, indicating other mechanisms underlie the relationship between acute sitting and mood disturbances.

Digoxin Ameliorates Glymphatic Transport and Cognitive Impairment in a Mouse Model of Chronic Cerebral Hypoperfusion

The glymphatic system plays a pivotal role in maintaining cerebral homeostasis. Chronic cerebral hypoperfusion, arising from small vessel disease or carotid stenosis, results in cerebrometabolic disturbances ultimately manifesting in white matter injury and cognitive dysfunction. However, whether the glymphatic system serves as a potential therapeutic target for white matter injury and cognitive decline during hypoperfusion remains unknown. Here, we established a mouse model of chronic cerebral hypoperfusion via bilateral common carotid artery stenosis. We found that the hypoperfusion model was associated with significant white matter injury and initial cognitive impairment in conjunction with impaired glymphatic system function. The glymphatic dysfunction was associated with altered cerebral perfusion and loss of aquaporin 4 polarization. Treatment of digoxin rescued changes in glymphatic transport, white matter structure, and cognitive function. Suppression of glymphatic functions by treatment with the AQP4 inhibitor TGN-020 abolished this protective effect of digoxin from hypoperfusion injury. Our research yields new insight into the relationship between hemodynamics, glymphatic transport, white matter injury, and cognitive changes after chronic cerebral hypoperfusion.

Polyphenols and neuroprotection: Therapeutic implications for cognitive decline

Dietary polyphenols have been the focus of major interest for their potential benefits on human health. Several preclinical studies have been conducted to provide a rationale for their potential use as therapeutic agents in preventing or ameliorating cognitive decline. However, results from human studies are scarce and poorly documented. The aim of this review was to discuss the potential mechanisms involved in age-related cognitive decline or early stage cognitive impairment and current evidence from clinical human studies conducted on polyphenols and the aforementioned outcomes. The evidence published so far is encouraging but contrasting findings are to be taken into account. Most studies on anthocyanins showed a consistent positive effect on various cognitive aspects related to aging or early stages of cognitive impairment. Studies on cocoa flavanols, resveratrol, and isoflavones provided substantial contrasting results and further research is needed to clarify the therapeutic potential of these compounds. Results from other studies on quercetin, green tea flavanols, hydroxycinnamic acids (such as chlorogenic acid), curcumin, and olive oil tyrosol and derivatives are rather promising but still too few to provide any real conclusions. Future translational studies are needed to address issues related to dosage, optimal formulations to improve bioavailability, as well as better control for the overall diet, and correct target population.

Blood pressure, frailty and dementia

High blood pressure (BP) affects 75% of people aged over 70. Ageing alters BP homeostasis, resulting in postural hypotension and increased BP variability. Co-morbidity and frailty add complexity to understanding BP changes in later life. Longitudinal BP declines are likely driven by accumulating co-morbidity and are accelerated in both frailty and dementia. This narrative review summarises what is known about the association between BP and frailty, the clinical management of BP in frailty and the association between BP, cognitive decline and dementia.

Atherosclerosis: The Culprit and Co-victim of Vascular Dementia

Vascular dementia (VD), a cerebrovascular disease which causes cognitive impairment, is one of the significant factors that affects the quality of senectitude. Atherosclerosis (AS) is a chronic inflammatory syndrome and closely associated with VD. Analyzing the role of AS in VD contribute greatly to its early detection and prevention, but their relationship has not been integrated into a complete network. This review summarizes AS biomarkers as VD predictors for the first time and describes the direct mechanisms of AS causing VD from five aspects: vascular morphogenesis, hemodynamic change, neurovascular unit damage (NVU), oxidative stress, and microRNA (miRNA). Finally, it discriminates the relationship between AS and VD in common risk factors which can be disease or some molecules. In particular, these data imply that the role of AS in VD is not only a pathogenic factor but also a comorbidity in VD. This review aims to bring new ideas for the prediction and treatment of VD.