Impact of nocturnal heart rate variability on cerebral small-vessel disease progression: a longitudinal study in community-dwelling elderly Japanese

Implication of heart rate variability on cerebral small vessel disease: A potential therapeutic target

OBJECTIVE

This study aimed to investigate the relationships of heart rate variability (HRV) with the presence, severity, and individual neuroimaging markers of cerebral small vessel disease (CSVD).

METHOD

A total of 4676 participants from the Third China National Stroke Registry (CNSR-III) study were included in this cross-sectional analysis. CSVD and its markers, including white matter hyperintensity (WMH), lacunes, enlarged perivascular spaces (EPVS), cerebral microbleeds (CMBs), and brain atrophy (BA), were evaluated. Two common HRV parameters, including the square root of the mean of the sum of the squares of differences between adjacent N-N intervals (RMSSD) and the standard deviation of all N-N intervals (SDNN), were used to evaluate the function of the autonomic nervous system (ANS). Binary or ordinal logistic regression analyses were performed to investigate the association between HRV and CSVD. In addition, two-sample mendelian randomization (MR) analyses were performed to investigate the causality of HRV with CSVD.

RESULTS

RMSSD was significantly associated with total burden of CSVD (Wardlaw's scale, common odds ratio [cOR] 0.80, 95% confidence interval [CI] 0.67-0.96, p = 0.02; Rothwell's scale, cOR 0.75, 95% CI 0.60-0.93, p = 0.008) and the presence of CSVD (Rothwell, OR 0.75, 95% CI 0.60-0.93, p = 0.008). However, no significant associations between SDNN and the presence or total burden of CSVD were observed. Moreover, RMSSD was related to WMH burden (OR 0.80, 95% CI 0.66-0.96, p = 0.02), modified WMH burden (cOR 0.82, 95% CI 0.69-0.97, p = 0.02), and Deep-WMH (OR 0.75, 95% CI 0.62-0.91, p = 0.003), while SDNN was related to Deep-WMH (OR 0.80, 95% CI 0.66-0.96, p = 0.02) and BA (cOR 0.80, 95% CI 0.68-0.95, p = 0.009). Furthermore, adding HRV to the conventional model based on vascualr risk factors enhanced the predictive performance for CSVD, as validated by the integrated discrimination index (p < 0.05). In addition, no causality between HRV and CSVD was observed in two-sample MR analyses.

CONCLUSION

Decreased HRV may be a potential risk factor of CSVD, implying the possible role of the ANS in the pathogenesis of CSVD.

The combination of nondipper pulse rate pattern and nighttime high pulse rate variability is associated with an increase of brain natriuretic peptide: the J-HOP study

The association between pulse rate (PR) and short-term PR variability and hypertensive organ damage has not been clarified. We enrolled 1439 patients from the J-HOP study. We calculated the standard deviation (SD) of PR in the nighttime using nighttime PR measurements at 30-min intervals. The SDs of PR (PR-SD) at nighttime were divided into quartiles (Q1-Q4). Nondipper PR was defined as (awake PR-sleep PR) < 0.1. Brain natriuretic peptide (BNP) levels were higher in patients with nondipper PR status in Q4 of PR-SD (nondipper PR/PR-SD Q4) than those with nondipper PR/PR-SD Q1-Q3 (37.8 vs 21.9 pg/mL, p = 0.041). The percentage of BNP > 100 pg/mL for patients with dipper PR/PR-SD Q1-Q3 was 5.2%, that for dipper PR/PR-SD Q4 was 4.8%, that for nondipper PR/PR-SD Q1-Q3 was 13.0%, and that for nondipper PR/PR-SD Q4 was 20.0% (ANOVA p < 0.001). In conclusion, BNP was high in patients having nondipper PR and high nocturnal PR-SD. Conceptual figure of subclinical heart failure and nondipper PR, PR variability. PR: pulse rate.

Heart rate variability is associated with cerebral small vessel disease in patients with diabetes

OBJECTIVE

Low heart rate variability (HRV), an indicator of autonomic nervous system dysfunction, has been associated with increased all-cause and cardiovascular mortality and incident stroke. However, the relationship between HRV and cerebral small vessel disease (CSVD) showed contradictory results. We aimed to examine the relationship of HRV and total burden of CSVD and each of the magnetic resonance imaging (MRI) markers of CSVD.

METHODS

We recruited 435 patients who attended our hospital for physical examination between June 2020 and August 2021. All underwent 24-h Holter monitoring and MRI scan. The standard deviation of normal-to-normal intervals (SDNN) was selected as the method for HRV assessment. The presence of severe white matter hyperintensity, lacunes, and >10 enlarged basal ganglia perivascular spaces, and cerebral microbleeds were added for estimating the CSVD score (0-4). Multivariate logistic analyses was performed to assess whether HRV was independently associated with the burden of CSVD and each of the MRI markers of CSVD, with and without stratification by prevalent diabetes.

RESULTS

This study included 435 subjects with a mean age of 64.0 (57.0-70.0) years; 49.4% of the patients were male, and 122 (28.0%) had a history of diabetes. In multivariate analyses, lower SDNN was independently associated with total burden of CSVD and the presence of enlarged perivascular spaces in all subjects. According to diabetes stratification, lower SDNN was independently associated with total burden of CSVD and each MRI markers of CSVD separately only in the diabetic group.

CONCLUSIONS

Lower HRV was associated with total burden of CSVD and each MRI markers of CSVD separately among diabetic patients, but not among non-diabetic patients.

Relationship between heart rate variability and cognitive function in patients with enlarged perivascular space

Objective

To explore the relationship between heart rate variability (HRV), the brain distribution of enlarged perivascular space (EPVS), and cognitive impairment in patients with EPVS.

Materials and methods

The clinical and imaging data of 199 patients with EPVS were retrospectively analyzed. EPVS load in the basal ganglia (BG) and centrum semiovale (CS) regions were assessed using the Potter’s method. Cognitive function was evaluated using the Montreal Cognitive Assessment Scale. A logistic regression model was used to analyze the relationship between HRV, the brain distribution of EPVS and cognitive function in patients with EPVS. A receiver operating characteristic curve was used to assess the predictive value of HRV for cognitive function in patients with EPVS.

Results

Of the 199 patients, 27 and 42 presented with severe BG-EPVS and cognitive impairment, respectively. Significant differences were observed in the root mean square of successive differences of normal-normal (NN) intervals for period of interest (rMSSD), the percentage of adjacent NN intervals greater than 50 ms (PNN50), and the ratio of low-frequency power (LF) to high-frequency power (HF) between the mild and severe BG-EPVS groups (P &lt; 0.05). Patients who presented with and without cognitive impairment differed significantly in the standard deviation of NN intervals (SDNN), rMSSD, PNN50, total power, LF, and LF/HF (P &lt; 0.05). rMSSD (odds ratio [OR] 0.871, 95% confidence interval [CI] 0.768–0.988) and LF/HF (OR 3.854, 95% CI 1.196–12.419) were independent influencing factors of BG-EPVS, and rMSSD (OR 0.936, 95% CI 0.898–0.976) was an independent influencing factor of cognitive impairment in patients with EPVS. The optimal cut-off point was 0.312, with an area under the curve of 0.795 (95% CI 0.719–0.872) for predicting cognitive impairment in patients with EPVS by rMSSD.

Conclusion

Reduced HRV is involved in the pathophysiological mechanisms of the formation and development of BG-EPVS and is associated with cognitive impairment in patients with EPVS, independent of CS-EPVS. For patients with HRV changes but without autonomic nervous system symptoms, positive intervention may slow the occurrence or progression of EPVS and cognitive impairment in patients with EPVS.

Decreased nighttime heart rate variability and progression of white matter hyperintensities of presumed vascular origin. A prospective study in community-dwelling older adults

OBJECTIVES

Evidence on the role of autonomic dysfunction on white matter hyperintensities (WMH) progression is limited. This study aims to assess the impact of a low nighttime heart rate variability (HRV) on WMH progression in community-dwelling older adults.

MATERIALS AND METHODS

Following a prospective longitudinal study design, all individuals aged ≥60 years enrolled in the Atahualpa Project Cohort from 2012 to 2019 were invited to receive baseline HRV determinations through 24-h Holter monitoring, together with clinical interviews and brain MRIs. These individuals were periodically followed by means of annual door-to-door surveys, and those who also received brain MRIs at the end of the study (May 2021) were included in the analysis. Poisson regression models, adjusted for relevant confounders, were fitted to assess the incidence rate ratio (IRR) of WMH progression according to nighttime standard deviation of normal-to-normal R-R intervals (SDNN).

RESULTS

This study included 254 individuals aged ≥60 years (mean age: 65.4 ± 5.9 years; 55% women). The mean nighttime SDNN was 116.8 ± 36.3 ms. Follow-up MRIs showed WMH progression in 103 (41%) individuals after a median follow-up of 6.5 years. In unadjusted analyses, nighttime SDNN was lower among participants who developed WMH progression than in those who did not (p < 0.001). A Poisson regression model, adjusted for relevant covariates, disclosed a significantly inverse association between nighttime SDNN and WMH progression (IRR: 0.99; 95% C.I.: 0.98-0.99; p = 0.014).

CONCLUSIONS

Study results show an inverse association between decreased nighttime SDNN and WMH progression, and provide support for the role of sympathetic overactivity in this relationship.

The Association Between the Prevalence, Medication Adherence and Control of Hypertension and the Prevalence of Mild Cognitive Impairment in Rural Northern China: A Cross-Sectional Study

INTRODUCTION

High blood pressure is one of the main modifiable risk factors for dementia. However, it remains unclear whether lowering the blood pressure effectively prevents cognitive impairment. Our objective was to explore the association between the prevalence, medication adherence and control of hypertension and mild cognitive impairment (MCI) among elderly individuals in northern China.

METHODS

A two-stage clustering sampling method was used, and 9036 participants aged ≥65 years were included in the analysis. The Mini-Mental State Examination and activities of daily living were used to assess participants' cognitive function. Demographic characteristics (gender, age, marital status, education level, occupation), history and duration of hypertension, use of antihypertensive medications (AHMs) and its control effect were obtained.

RESULTS

The prevalence of MCI in all participants was 18.1%, and the prevalence of MCI was significantly higher in hypertensive subjects than in normotensive subjects (19.7% vs 16.2%, P < 0.01). Furthermore, in hypertensive patients, the prevalence of MCI was lower in those with good adherence (17.3%) than in those with poor adherence (23.7%, P < 0.01) and lower in those controlled (16.5%) than in those with uncontrolled adherence (20.8%, P < 0.01). In univariate analyses, being female gender, increased age, agriculture occupation, unmarried and widow, less than primary school and middle school were associated with MCI prevalence. The assessment of the hypertensive patients revealed the adjusted OR (95% CI) of having MCI in those with poor adherence to AHMs was 1.32 (1.14-1.54) compared with those having good adherence.

CONCLUSION

There is an association between the prevalence of hypertension, adherence to AHMs and MCI, suggesting that hypertensives should be screened for MCI to provide improved diagnoses and optimal therapeutics for cognitive decline prevention, especially in poor AHM adherence.

Night-Time Non-dipping Blood Pressure and Heart Rate: An Association With the Risk of Silent Small Vessel Disease in Patients Presenting With Acute Ischemic Stroke

Background and Purpose: Nocturnal non-dipping blood pressure and heart rate are associated with an increased risk of cardiovascular disease. The effects of such variance on cerebrovascular disease have not been well studied.

Methods: The 24-h ambulatory blood pressure (ABPM) and heart rate were monitored with B-pro in patients with acute stroke within the initial week of hospital admission. The risk factor profiles, clinical presentation, imaging, and short-term prognosis were compared in nocturnal dippers and non-dippers (more than 10% nocturnal decrease) of blood pressure and heart rate.

Results: We enrolled 234 patients in whom ABPM and MRI data were available. Heart rate data were available in 180 patients. Lacunar sub-cortical stroke was the most common acute lesion (58.9%), while hypertension (74%) and diabetes (41.5%) were the most common associated risk factors. ABPM revealed non-dipping in 69% of patients. On univariate analysis, Small Vessel Disease (SVD) was significantly more frequent in non-dippers vs. dippers (BP: 56.8 vs. 40.3% p = 0.02; heart rate: 57.9 vs. 40.7% p = 0.03). Silent strokes were also more frequent in non-dippers vs. dippers (BP: 40.7 vs. 26.4% p = 0.35; heart rate: 44.6 vs. 25.4% p = 0.01). Multivariate analysis revealed SVD to be significantly related to age, hypertension, blood pressure non-dipping, and severity of symptoms at index event.

Conclusions: The presence of nocturnal non-dipping of blood pressure and heart rate are associated with an increased risk of silent stroke and SVD. Increased use of ABPM may allow for improved diagnosis of non-dippers.

Association Between Blood Pressure Variability With Dementia and Cognitive Impairment: A Systematic Review and Meta-Analysis

[Figure: see text].

Decreased nocturnal heart rate variability and potentially related brain regions in arteriosclerotic cerebral small vessel disease

Background

To assess heart rate variability (HRV) among patients with arteriosclerotic cerebral small vessel disease (CSVD) by comparing with control subjects, and to determine whether HRV parameters were related to structural alterations in brain regions involved in autonomic regulation among CSVD patients.

Methods

We consecutively recruited subjects aged between 50 and 80 years who visited the Stroke Prevention Clinic of our hospital and have completed brain magnetic resonance imaging examination from September 1, 2018 to August 31, 2019. Polysomnography and synchronous analyses of HRV were then performed in all participants. Multivariable binary logistic regression was used to identify the relationship between HRV parameters and CSVD. Participants were invited to further undergo three-dimensional brain volume scan, and the voxel based morphometry (VBM) analysis was used to identify gray matter atrophy.

Results

Among 109 participants enrolled in this study, 63 were assigned to the arteriosclerotic CSVD group and 46 to the control group. Lower standard deviation of normal-to-normal intervals (SDNN, OR = 0.943, 95% CI 0.903 to 0.985, P = 0.009) and higher ratio of low to high frequency power (LF/HF, OR = 4.372, 95% CI 1.033 to 18.508, P = 0.045) during the sleep period were associated with CSVD, independent of traditional cerebrovascular risk factors and sleep disordered breathing. A number of 24 CSVD patients and 21 controls further underwent three-dimensional brain volume scan and VBM analysis. Based on VBM results, SDNN during the awake time (β = 0.544, 95% CI 0.211 to 0.877, P = 0.001) and the sleep period (β = 0.532, 95% CI 0.202 to 0.862, P = 0.001) were both positively related with gray matter volume within the right inferior frontal gyrus only among CSVD patients.

Conclusions

Decreased nocturnal HRV is associated with arteriosclerotic CSVD independent of traditional cerebrovascular risk factors and sleep disordered breathing. The structural atrophy of some brain regions associated with cardiac autonomic regulation sheds light on the potential relationship.

Trial registration

Trial registration number: ChiCTR1800017902. Date of registration: 20 Aug 2018.

A two-sample Mendelian randomization analysis of heart rate variability and cerebral small vessel disease

Cerebral small vessel disease (cSVD) is correlated with a high risk of stroke and cognitive impairment. Previous studies between heart rate variability (HRV) and cSVD revealed paradoxical results. The authors aimed to investigate the relationship between HRV and cSVD using Mendelian randomization analysis. Genetic instruments for HRV were obtained from previous genome‐wide association studies. They applied inverse variance‐weighted analysis, weighted median analysis, simple median analysis, and Mendelian randomization–Egger regression to evaluate the associations of HRV with white matter hyperintensity (WMH) and small vessel stroke (SVS) in the UK Biobank neuroimaging dataset and the MEGASTROKE genome‐wide association study dataset. Two genetically predicted traits of HRV (the root mean square of the successive differences of inter beat intervals [RMSSD] and the peak‐valley respiratory sinus arrhythmia or high frequency power [pvRSA/HF]) were suggestively associated with WMH (β 0.26, 95% confidence interval [CI] 0.04–0.49, p = .02; β 0.14, 95% CI 0.02–0.27, p = .03, respectively). Genetically predicted traits of HRV were not significantly associated with SVS. This study provides genetic support for a suggestive causal effect of HRV (RMSSD, pvRSA/HF) on WMH but not SVS.

Diurnal Blood Pressure and Heart Rate Variability in Hypertensive Patients with Cerebral Small Vessel Disease: A Case-Control Study

BACKGROUND

Whether autonomic dysfunction contributes to cerebral small vessel disease (CSVD) remains unclear. This study aimed to explore the relationship between CSVD and blood pressure variability (BPV) and heart rate variability (HRV).

METHODS

This case-control study recruited 50 patients with CSVD and 50 non-CSVD hypertensive age- and gender-matched controls. All participants completed a 24-h ambulatory electrocardiogram recording and ambulatory BP monitoring (ABPM). Differences in HRV and BPV between the two groups were examined. BPV indices assessed by ABPM included mean systolic BP (SBP), mean diastolic BP (DBP), coefficient of variation and weighted standard deviation of SBP and DBP.

RESULTS

CSVD patients had significant higher 24-h mean systolic BP (SBP), 24-h mean diastolic BP (DBP), daytime mean SBP, nocturnal mean SBP, and nocturnal mean DBP (P < .05 for all). CSVD patients had a significant lower nocturnal SBP fall rate compared with controls (median: 1.0 versus 6.2, respectively; P < .001) and were more likely to be non-dippers and reverse dippers. There were no differences in HRV variables between the two groups. Five logistic models were built to explore the correlations between BPV indices and CSVD. BPV indices were separately entered into the logistic regression models, together with hyperlipidemia, ischemic stroke history, current use of anti-hypertensive agents, and serum blood urea nitrogen. In models 1-3, 24-h mean SBP and nocturnal mean SBP and DBP were significantly correlated with CSVD (r² = 0.308-0.340). In model 4, the nocturnal SBP fall rate was negatively correlated with CSVD (odds ratio [OR] = 0.871, 95% confidence interval [CI] = 0.804-0.943; P = .001), with r² = 0.415 fitting the model. In model 5, the pattern of SBP dipping was significantly associated with CSVD, with non-dipper (OR = 8.389, 95%CI = 1.489-47.254; P = .016) and reverse dipper (OR = 27.008, 95%CI = 3.709-196.660; P = .001) having the highest risks of CSVD (r² = 0.413).

CONCLUSIONS

Lower nocturnal SBP fall rate is associated with CSVD. Non-dipper and reverse dipper hypertensive patients have a higher risk of CSVD.

Increased nocturnal arterial pulsation frequencies of obstructive sleep apnoea patients is associated with an increased number of lapses in a psychomotor vigilance task

Objectives

Besides hypoxaemia severity, heart rate variability has been linked to cognitive decline in obstructive sleep apnoea (OSA) patients. Thus, our aim was to examine whether the frequency domain features of a nocturnal photoplethysmogram (PPG) can be linked to poor performance in the psychomotor vigilance task (PVT).

Methods

PPG signals from 567 suspected OSA patients, extracted from Type 1 diagnostic polysomnography, and corresponding results of PVT were retrospectively examined. The frequency content of complete PPGs was determined, and analyses were conducted separately for men (n=327) and women (n=240). Patients were grouped into PVT performance quartiles based on the number of lapses (reaction times ≥500 ms) and within-test variation in reaction times. The best-performing (Q1) and worst-performing (Q4) quartiles were compared due the lack of clinical thresholds in PVT.

Results

We found that the increase in arterial pulsation frequency (APF) in both men and women was associated with a higher number of lapses. Higher APF was also associated with higher within-test variation in men, but not in women. Median APF (β=0.27, p=0.01), time spent under 90% saturation (β=0.05, p<0.01), female sex (β=1.29, p<0.01), older age (β=0.03, p<0.01) and subjective sleepiness (β=0.07, p<0.01) were significant predictors of belonging to Q4 based on lapses. Only female sex (β=0.75, p<0.01) and depression (β=0.91, p<0.02) were significant predictors of belonging to Q4 based on the within-test variation.

Conclusions

In conclusion, increased APF in PPG provides a possible polysomnography indicator for deteriorated vigilance especially in male OSA patients. This finding highlights the connection between cardiorespiratory regulation, vigilance and OSA. However, our results indicate substantial sex-dependent differences that warrant further prospective studies.

Prevalence of Psychiatric Morbidity and Cognitive Impairment among Patients Attending the Rural Noncommunicable Disease Clinic

Objective  This study aimed to assess the prevalence of cognitive impairment and psychiatric morbidity among the patients attending the rural noncommunicable disease clinic after controlling for various confounders (i.e., psychological morbidity, obesity, gender, level of education, duration of the illness and age).

Materials and Methods  One-hundred twenty-four patients were evaluated on the Hindi Mental State Examination for the cognitive function, Physical Health Questionnaire-9 for depression, and Generalized Anxiety Disorder-7 for anxiety disorders.

Results  About one-fourth (26.6%) of the participants had cognitive impairment. The prevalence of cognitive impairment was more among patients with hypertension (35.5%) as compared with the diabetes mellitus (13.6%) and those with comorbid hypertension and diabetes mellitus (26.6%). About one of the participants had depression (35.5%) and 29% of the patients had anxiety disorder. No significant difference was found in the level of cognitive deficits between those with hypertension and diabetes mellitus, when the confounding factors were not taken into account in the analysis. However, after controlling for psychiatric morbidity, obesity, gender, level of education, duration of the illness and age, those with hypertension were found to have significantly higher level of cognitive impairment compared with those with diabetes mellitus. A higher level of dysfunction was seen in the domains of orientation, registration, attention, recall, language, and visuospatial domains.

Conclusion  Present study suggests that patients of hypertension have higher level of cognitive impairment, when compared with those with diabetes mellitus, even after controlling for various confounders. Lack of difference between the two groups can be accounted by the confounding variables.

The Association of Autonomic Nervous System Function With Ischemic Stroke, and Treatment Strategies

Acute ischemic stroke, especially minor stroke, and transient ischemic attack have high risks of recurrence and exacerbation into severe ischemic strokes. It remains challenging to perform risk stratification and screen high-risk groups for initiation of early treatment in these patients. Moreover, with the growing population of patients with chronic small vessel disease, the mechanisms and clinical implications require further investigation. Traditional tools such as the ABCD2 score (age, blood pressure, clinical features, duration of symptoms, diabetes) have only moderate predictive value in patients with transient ischemic attack or minor stroke. By contrast, measurement of changes in heart rate variability (HRV) is an important and novel tool for risk stratification and outcome prediction in patients with cardiovascular diseases, as it reflects the overall level of autonomic nervous system dysfunction. Thus, abnormal HRV may be useful for prognosis and improve stratification of stroke patients with diverse risks. HRV may also partially explain autonomic nervous dysfunction and other manifestations during the process of chronic cerebral small vessel disease. In summary, measurement of HRV may contribute to early initiation of interventions in acute or chronic stroke patients using novel treatments involving rebalancing of autonomic nervous system function.

Effect of Heart Rate Variability on the Association Between the Apnea-Hypopnea Index and Cerebral Small Vessel Disease

Background and Purpose- The apnea-hypopnea index (AHI) is associated with cerebral small vessel disease (cSVD), but pathogenesis of this association is elusive. We aimed to assess the effect of nighttime heart rate variability (HRV)-as a proxy of sympathetic upregulation-on the aforementioned association. Methods- Atahualpa residents aged ≥60 years undergoing brain magnetic resonance imaging, polysomnography, and 24-hour Holter monitoring (N=176) were included. The presence of moderate-to-severe white matter hyperintensities, deep cerebral microbleeds, lacunar infarcts, and >10 enlarged basal ganglia perivascular spaces were added for estimating the cSVD score. Interaction models were fitted to assess the effect modification of nighttime HRV in the association between the AHI and the cSVD score, and mediation analysis was utilized to assess the proportion of total effect by nighttime HRV on this association. Results- Generalized linear models showed a significant association between the AHI and the cSVD score (P=0.025), as well as a significant inverse association between nighttime HRV and the cSVD score (P=0.002), but no association between daytime HRV and the cSVD score (P=0.097). Interaction models showed a significant interaction of nighttime HRV on the association between AHI and the cSVD score (P=0.001), and mediation analysis found that the percent of total effect between AHI and cSVD score mediated by HRV was 30.8%. Predictive marginal means of the cSVD score were highly significant when the 10th percentile of nighttime HRV was compared across categories of 10th and 90th percentiles of the AHI (cSVD score margins, 0.61 [95% CI, 0.37-0.86] versus 1.67 [95% CI, 1.26-2.09]). Contour plots showed the effect of nighttime (but not daytime) HRV on the association between AHI and the cSVD score. Conclusions- This study shows an important effect of nighttime HRV on the association between the AHI and the cSVD score and provides further support for the role of sympathetic overactivity on this association.

Strong and specific associations between cardiovascular risk factors and white matter micro- and macrostructure in healthy aging

Cardiovascular health declines with age, increasing the risk of hypertension and elevated heart rate in middle and old age. Here, we used multivariate techniques to investigate the associations between cardiovascular health (diastolic blood pressure, systolic blood pressure, and heart rate) and white matter macrostructure (lesion volume and number) and microstructure (as measured by diffusion-weighted imaging) in the cross-sectional, population-based Cam-CAN cohort (N = 667, aged 18–88). We found that cardiovascular health and age made approximately similar contributions to white matter health and explained up to 56% of variance therein. Lower diastolic blood pressure, higher systolic blood pressure, and higher heart rate were each strongly, and independently, associated with white matter abnormalities on all indices. Body mass and exercise were associated with white matter health, both directly and indirectly via cardiovascular health. These results highlight the importance of cardiovascular risk factors for white matter health across the adult lifespan and suggest that systolic blood pressure, diastolic blood pressure, and heart rate affect white matter health via separate mechanisms.

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Cardiovascular health is related to white matter lesion burden and diffusivity.

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Low diastolic pressure, high systolic pressure, and higher heart rate contribute independently.

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Cardiovascular health and age explain up to 56% of variance in white matter health.

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The uncinate fasciculus, inferior fronto-occipital fasciculus, and forceps minor show most sensitivity.

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Lower BMI and more exercise may have protective effects.

Sympathetic Overactivity Based on Heart-Rate Variability in Patients with Obstructive Sleep Apnea and Cerebral Small-Vessel Disease

Background and Purpose

Obstructive sleep apnea (OSA) is associated with cerebral white-matter changes (WMC), but the underlying mechanisms are not completely understood. Our aim was to identify the cardiovascular autonomic characteristics during sleep that are associated with cerebral WMC in OSA patients.

Methods

We recruited subjects from our sleep-center database who underwent both polysomnography and brain MRI within a 1-year period. Sixty patients who had OSA with WMC (OSA+WMC), 44 patients who had OSA without WMC (OSA−WMC), and 31 control subjects who had neither OSA nor WMC were analyzed. Linear and nonlinear indices of heart-rate variability (HRV) were analyzed in each group according to different sleep stages and also over the entire sleeping period.

Results

Among the nonlinear HRV indices, the Poincaré ratio (SD12) during the entire sleep period was significantly increased in the OSA+WMC group, even after age adjustment. Meanwhile, detrended fluctuation analysis 1 during non-rapid-eye-movement sleep tended to be lowest in the OSA+WMC group. These indices were altered regardless of the presence of hypertension or diabetes. In the subgroup analysis of middle-aged OSA patients, approximate entropy during rapid-eye-movement sleep was significantly lower in OSA+WMC patients than in OSA−WMC patients. Overall, the nonlinear HRV indices suggest that sympathetic activity was higher in the OSA+WMC group than in the OSA−WMC and control groups.

Conclusions

Our findings suggest that dysregulation of HRV, especially overactivation of sympathetic tone, could be a pathophysiologic mechanism underlying the development of WMC in OSA patients.

Arterial pressure lability is improved by sodium-glucose cotransporter 2 inhibitor in streptozotocin-induced diabetic rats

To prevent cardiovascular events in patients with diabetes mellitus (DM), it is essential to reduce arterial pressure (AP). Sodium-glucose cotransporter 2 inhibitor (SGLT2i) prevents cardiovascular events via the depressor response in patients with DM. In the present study, we examined whether SGLT2i ameliorates AP lability in DM rats. Ten-week-old male Sprague-Dawley rats were administered a single intravenous injection of streptozotocin (50 mg kg^-1) and were divided into three groups treated with low-dose SGLT2i, vehicle (VEH) or subcutaneously implanted insulin pellets (SGLT2i, VEH and Insulin group, respectively) for 14 days. SGLT2i reduced blood glucose, but its effect was lower than that of insulin. The telemetered mean AP at the end of the experiment did not differ among the SGLT2i, Insulin and VEH groups (83±7 vs. 98±9 vs. 90±8 mm Hg, respectively, n=5 for each). The standard deviation of AP as the index of lability was significantly smaller during the active period in the SGLT2i group than in the VEH group (5.6±0.5 vs. 7.0±0.7 mm Hg, n=5 for each, P<0.05). Sympathetic nerve activity during the active period was significantly lower in the SGLT2i group than in the VEH group. Baroreflex sensitivity (BRS) was significantly higher in the SGLT2i group than in the VEH group. The standard deviation of AP and sympathoexcitation did not differ between the Insulin and VEH groups. In conclusion, SGLT2i at a non-depressor dose ameliorated the AP lability associated with sympathoinhibition during the active period and improved the BRS in streptozotocin-induced DM rats.

Relationships between 24-h blood pressure variability and 24-h central arterial pressure, pulse wave velocity and augmentation index in hypertensive patients

Twenty-four-h blood pressure variability (BPV) predicts cardiovascular complications in hypertension, but its association with pulse wave indices (central arterial pressure, pulse wave velocity (PWV) and augmentation index (AIx)) is poorly understood. In the present study, we assessed the degree of the effect of 24-h BPV on 24-h pulse wave indices. Brachial blood pressure was measured non-invasively over the 24 h with an electronic, oscillometric, automated device (BPLab) in 661 uncomplicated treated or untreated hypertensive patients. Digitalized oscillometric waveforms were analyzed with a validated algorithm to obtain pulse wave indices. Twenty-four-h BPV was calculated as the unweighted (SDu) or weighted s.d. (SDw) of the mean blood pressure or as the average real variability (ARV). Twenty-four-h systolic BPV showed a direct and significant relationship with the central arterial systolic pressure (r=0.28 SDu, r=0.40 SDw, r=0.34 ARV), PWV (r=0.10 SDu, r=0.21 SDw, r=0.19 ARV) and AIx (r=0.17 SDu, r=0.27 SDw, r=0.23 ARV). After adjustment for age, sex, body mass index, antihypertensive treatment and 24-h systolic blood pressure, the relationship lost some power but was still significant for all measures, except for the AIx. Pulse wave indices were higher in patients with high BPV than in those with low BPV: after adjustment, these differences were abolished for the AIx. The diastolic BPV showed a weak association with the pulse wave indices. In conclusion, in hypertensive patients, 24-h systolic BPV is moderately and independently associated with 24-h central arterial pressure and stiffness.

The association between the prevalence, treatment and control of hypertension and the risk of mild cognitive impairment in an elderly urban population in China

It remains unclear whether lowering the blood pressure effectively prevents cognitive impairment. The aim of the current study was to explore the association between the prevalence, treatment and control of hypertension and the risk of mild cognitive impairment (MCI) among elderly Chinese people. This is a cross-sectional study conducted in Beijing, China. A two-stage stratified clustering sampling method was used, and 2065 participants, aged ⩾60 years, were included in the analysis. The Mini-Mental State Examination was used to assess participants' cognitive function. The prevalence of MCI was higher in hypertensive (16.5%) than in normotensive individuals (13.1% P=0.043). Furthermore, in those hypertensive patients, the prevalence of MCI was lower in those treated (14.9%) than in those not treated (19.9% P=0.019) and lower in those controlled (13.4%) than in those uncontrolled (17.9% P=0.042). The adjusted odds ratio (OR; 95% confidence interval (CI)) of having MCI was 1.59 (1.07–2.35) in those with hypertension compared with those normotensive individuals. The assessment of the hypertensive patients revealed the adjusted OR (95% CI) of having MCI in those with treated hypertension was 0.60 (0.42–0.86) compared with those untreated hypertension, and in those with controlled hypertension was 0.64 (0.43–0.93) compared with those non-controlled hypertension (regardless of treatment). However, among the treated hypertensive patients, there was no difference in the prevalence of MCI between the patients who reached and those who did not reach their treatment goal. We suggest that improved diagnoses and optimal therapeutics are needed to achieve the aim of cognitive decline prevention.