The effects of short-term blood pressure variability and nighttime blood pressure levels on cognitive function

Nocturnal blood pressure dipping, blood pressure variability, and cognitive function in early and middle-aged adults

Higher nighttime blood pressure (BP), less BP dipping, and higher BP variability have been linked with worse cognitive function in the elderly. The goal of this study is to explore whether this relationship already exists in early and middle adulthood. We further examined whether ethnic differences between African Americans and European Americans in BP parameters can explain ethnic differences in cognitive function. 24-h ambulatory BP monitoring and cognitive function were obtained from 390 participants (average age: 37.2 years with a range of 25-50; 54.9% African Americans; 63.6% females). We observed that higher nighttime BP, decreased dipping, and higher variability were significantly associated with lower scores on the Picture Sequence Memory Test. Significant negative associations between variability and overall composite scores were also observed. No significant associations between average 24-h or daytime BP and cognitive function were observed. Ethnic differences in nighttime diastolic pressures and dipping can explain 6.81% to 10.8% of the ethnicity difference in the score of the Picture Sequence Memory Test (ps < .05). This study suggests that the associations of nighttime BP, dipping, and variability with cognitive function already exist in young and middle-aged adults. Ethnic differences in nighttime BP and dipping can at least partially explain ethnic differences in cognitive function. The stronger association of these parameters with cognitive function than daytime or average BP in this age range raises the importance of using ambulatory BP monitoring for more precise detection of abnormal BP patterns in young adulthood.

Blood Pressure Control in Elderly Chronic Kidney Disease Patients

In elderly chronic kidney disease (CKD) patients, isolated systolic hypertension is common, the rate of renal function decline is slow, and there is a high possibility of physical damage due to side effects such as drug use-related orthostatic hypotension. Therefore, there are still many questions about whether lowering blood pressure in elderly patients will actually improve prognosis. Since many blood pressure-related clinical studies exclude advanced CKD and the elderly, it is particularly difficult to define target blood pressure in these populations. A randomized controlled trial is needed to establish optimal blood pressure targets and treatment strategies in elderly patients with CKD. This review seeks to summarize the guidelines available at this time.

Abnormal circadian blood pressure regulation and cognitive impairment in α-synucleinopathies

Circadian blood pressure (BP) rhythm is important for the maintenance of healthy daily life, and its disruption is associated with poor outcomes. Cardiovascular autonomic failure is often observed in older populations but has a greater impact on neurodegenerative disorders such as α-synucleinopathies. These BP abnormalities include orthostatic hypotension (OH), supine hypertension (SH), and a loss of nocturnal BP fall. OH not only causes falls or syncope but is also related to cognitive impairment in α-synucleinopathies. For example, OH doubles or triples the risk for the development of cognitive impairment in Parkinson's disease (PD). The diffuse central and peripheral neuropathology of α-synuclein may contribute to both OH and cognitive impairment. Moreover, repeated cerebral hypoperfusion in OH is thought to be related to cerebrovascular and neuronal damage, which may cause cognitive impairment. SH, which often coexists with OH, is also associated with cognitive impairment through cerebrovascular damage, such as white matter lesions and cerebral microbleeds. The reverse-dipping (riser) pattern on ambulatory BP monitoring is commonly observed in PD (∼56%), regardless of disease duration and severity. It is also related to cognitive impairment and more pronounced when coexisting with OH. These abnormal circadian BP profiles may be synergistically associated with cognitive impairment and poor outcomes in α-synucleinopathies. Although evidence for aggressive control of BP dysregulation improving cognitive impairment and outcomes is limited, regular BP monitoring appears to be important for total management of α-synucleinopathies.

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

[Figure: see text].

Nocturnal blood pressure rise as a predictor of cognitive impairment among the elderly: a retrospective cohort study

Background

This study investigated the different blood pressure patterns that were evaluated by ambulatory blood pressure monitoring (ABPM) among elderly patients and explored the effect of pressure patterns on cognitive impairment and mortality.

Methods

A total of 305 elderly participants aged ≥65 years were divided into the cognitive impairment group (CI, n = 130) and the non-cognitive impairment group (NCI, n = 175) according to the MMSE score. All participants underwent ABPM to evaluate possible hypertensive disorder and cerebral MRI for the evaluation of cerebral small vessel disease. Follow-up was performed by telephone or medical records. The primary outcome was all-cause mortality. Secondary endpoints were major adverse cardiac and cerebrovascular events (MACCE).

Results

Among 305 participants, 130 (42.6%) were identified with cognitive impairment (CI), with average systolic blood pressure (BP) of 127 mmHg and diastolic BP of 66 mmHg. According to ABPM, only 13.1% had a dipper pattern, 45.6% had a nocturnal BP rise, while 41.3% had a non-dipper pattern. Compared with NCI patients, the CI group had significantly higher night-time systolic BP (130.0 ± 18.2 vs. 123.9 ± 15.1, p = 0.011), and more participants had nocturnal BP rise (52.3% vs. 40.6%, p = 0.042). Nocturnal BP rise was associated with greater white matter hyperintensities (WMH) (p = 0.013). After 2.03 years of follow-up, there were 35 all-cause deaths and 33 cases of major adverse cardiac and cerebrovascular events (MACCE). CI was independently associated with all-cause mortality during long-term observation (p < 0.01). Nocturnal BP rise had no significant predictive ability for all-cause mortality in elderly patients (p = 0.178).

Conclusions

Nocturnal BP rise contributed to greater cognitive impairment in elderly patients. Not nocturnal BP rise, but CI could significantly increase all-cause mortality. Controlling BP based on ABPM is critical for preventing the progression of cognitive dysfunction.

Childhood Hypertension and Effects on Cognitive Functions: Mechanisms and Future Perspectives

Pediatric hypertension is currently one of the most common health concerns in children, given its effects not only on cardiovascular but also cognitive functions. There is accumulating evidence suggesting neurocognitive dysfunction in hypertensive children that could persist even into adulthood. Identifying the precise mechanism(s) underlying the association between childhood hypertension and cognitive dysfunction is crucial as it could potentially lead to the discovery of "druggable" biological targets facilitating the development of treatments. Here, we discuss some of the proposed pathophysiological mechanisms underlying childhood hypertension and cognitive deficits and suggest strategies to address some of the current challenges in the field. The various research studies involving hypertensive adults indicate that long-term hypertension may produce abnormal cerebrovascular reactivity, chronic inflammation, autonomic dysfunction, or hyperinsulinemia and hypercholesterolemia, which could lead to alterations in the brain's structure and functions, resulting in cognitive dysfunction. In light of the current literature, we propose that dysregulation of the hypothalamus-pituitaryadrenal axis, modifications in endothelial brain-derived neurotrophic factor and the gut microbiome may also modulate cognitive functions in hypertensive individuals. Moreover, the above-mentioned pathological states may further intensify the detrimental effects of hypertension on cognitive functions. Thus, treatments that target not only hypertension but also its downstream effects may prove useful in ameliorating hypertension-induced cognitive deficits. Much remains to be clarified about the mechanisms and treatments of hypertension-induced cognitive outcomes in pediatric populations. Addressing the knowledge gaps in this field entails conducting not only clinical research but also rigorous basic and translational studies.

Association of 24-Hour Ambulatory Blood Pressure Patterns with Cognitive Function and Physical Functioning in CKD

BACKGROUND AND OBJECTIVES

Hypertension is highly prevalent in patients with CKD as is cognitive impairment and frailty, but the link between them is understudied. Our objective was to determine the association between ambulatory BP patterns, cognitive function, physical function, and frailty among patients with nondialysis-dependent CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Ambulatory BP readings were obtained on 1502 participants of the Chronic Renal Insufficiency Cohort. We evaluated the following exposures: (1) BP patterns (white coat, masked, sustained versus controlled hypertension) and (2) dipping patterns (reverse, extreme, nondippers versus normal dippers). Outcomes included the following: (1) cognitive impairment scores from the Modified Mini Mental Status Examination of <85, <80, and <75 for participants <65, 65-79, and ≥80 years, respectively; (2) physical function, measured by the short physical performance battery (SPPB), with higher scores (0-12) indicating better functioning; and (3) frailty, measured by meeting three or more of the following criteria: slow gait speed, muscle weakness, low physical activity, exhaustion, and unintentional weight loss. Cognitive function and frailty were assessed at the time of ambulatory BP (baseline) and annually thereafter. SPPB was assessed at baseline logistic and linear regression and Cox discrete models assessed the cross-sectional and longitudinal relationship between dipping and BP patterns and outcomes.

RESULTS

Mean age of participants was 63±10 years, 56% were male, and 39% were black. At baseline, 129 participants had cognitive impairment, and 275 were frail. Median SPPB score was 9 (interquartile range, 7-10). At baseline, participants with masked hypertension had 0.41 (95% CI, -0.78 to -0.05) lower SPPB scores compared with those with controlled hypertension in the fully adjusted model. Over 4 years of follow-up, 529 participants had incident frailty, and 207 had incident cognitive impairment. After multivariable adjustment, there was no association between BP or dipping patterns and incident frailty or cognitive impairment.

CONCLUSIONS

In patients with CKD, dipping and BP patterns are not associated with incident or prevalent cognitive impairment or prevalent frailty.

Smart Baroreceptor Activation Therapy Strikingly Attenuates Blood Pressure Variability in Hypertensive Rats With Impaired Baroreceptor

Increased blood pressure (BP) variability (BPV) is an independent risk factor of cardiovascular events among hypertensive patients. The arterial baroreceptor reflex is a powerful regulator of BP and attenuates BPV via a sympathetic negative feedback control. Conventional baroreceptor activation therapy (cBAT) electrically stimulates the carotid baroreceptors with constant stimulation parameters. While cBAT lowers BP, it does not mount a pressure feedback mechanism. We hypothesized that baroreceptor activation therapy with a pressure feedback system (smart BAT [sBAT]) is able to reduce BPV as well as lower BP. We developed sBAT that electrically stimulated baroreceptors at a frequency proportional to the difference between instantaneous BP and a preset reference pressure, and compared its performance with cBAT. In 14-week-old spontaneously hypertensive rats (n=6), we implanted BP telemeter and created impaired arterial baroreceptors by modified sino-aortic denervation. One week after surgical preparation, we administered sBAT, cBAT or no stimulation (sham) for 15 minutes and compared BP and BPV under freely moving condition. Both cBAT and sBAT significantly lowered mean BP (sham, 141.3±12.8; cBAT, 114.3±11.4; and sBAT, 112.0±7.3 mm Hg). Conventional BAT did not affect BPV at all, while sBAT significantly reduced BPV (sham, 15.4±2.6; cBAT, 16.0±5.2; and sBAT, 9.7±3.3 mm Hg). sBAT also prevented transient excessive BP rise and fall. In conclusion, sBAT was capable of reducing BP and attenuating BPV in hypertensive rats with impaired baroreceptor. sBAT is a novel treatment option for hypertensive patients with increased BPV.

Long-Term Blood Pressure Variability Across the Clinical and Biomarker Spectrum of Alzheimer's Disease

BACKGROUND

Elevated blood pressure is linked to cognitive impairment and Alzheimer's disease (AD) biomarker abnormality. However, blood pressure levels vary over time. Less is known about the role of long-term blood pressure variability in cognitive impairment and AD pathophysiology.

OBJECTIVE

Determine whether long-term blood pressure variability is elevated across the clinical and biomarker spectrum of AD.

METHODS

Alzheimer's Disease Neuroimaging Initiative participants (cognitively normal, mild cognitive impairment, AD [n = 1,421]) underwent baseline exam, including blood pressure measurement at 0, 6, and 12 months. A subset (n = 318) underwent baseline lumbar puncture to determine cerebrospinal fluid amyloid-β and phosphorylated tau levels. Clinical groups and biomarker-confirmed AD groups were compared on blood pressure variability over 12 months.

RESULTS

Systolic blood pressure variability was elevated in clinically diagnosed AD dementia (VIM: F2,1195 = 6.657, p = 0.001, η2 = 0.01) compared to cognitively normal participants (p = 0.001), and in mild cognitive impairment relative to cognitively normal participants (p = 0.01). Findings were maintained in biomarker-confirmed AD (VIM: F2,850 = 5.216, p = 0.006, η2 = 0.01), such that systolic blood pressure variability was elevated in biomarker-confirmed dementia due to AD relative to cognitively normal participants (p = 0.005) and in biomarker-confirmed mild cognitive impairment due to AD compared to cognitively normal participants (p = 0.04).

CONCLUSION

Long-term systolic blood pressure variability is elevated in cognitive impairment due to AD. Blood pressure variability may represent an understudied aspect of vascular dysfunction in AD with potential clinical implications.

Relationship between blood pressure variability and cognitive function in geriatric hypertensive patients with well-controlled blood pressure

BACKGROUND

Hypertension is an important risk factor for cardiovascular diseases and cognitive function. Blood pressure (BP) variability has been associated with cognitive dysfunction, but data are sparse regarding the relationship between BP variability and cognitive function in geriatric patients with well-controlled BP.

AIM

The aim of this study was to demonstrate the relationship between blood pressure variability and cognitive functions in geriatric hypertensive patients with well-controlled BP.

METHOD

We analyzed 435 hypertensive patients (167 male, 74.9 ± 8.3; 268 female, 76.1 ± 8.6) treated at least with one antihypertensive drug. All patients underwent ambulatory BP monitoring and the standardized mini mental test (sMMT).

RESULTS

We divided the weighted standard deviation (SD) of systolic BP (SBP) as a measure of BP variability into quartiles. The top quartile group (≥ 18.5 mmHg) had a significantly lower total sMMT score (23.3 ± 3.2, p < 0.001). According to the results of multivariate logistic regression analysis for sMMT, the SD of 24-h SBP was related to sMMT (p = 0.007, 95% confidence interval - 0.301 [- 0.370 to - 0.049]).

DISCUSSION

Although there are some inconsistencies among the studies investigating the relationship between blood pressure variability and cognitive functions in elderly patients, we demonstrated the relationship between increased 24-h blood pressure variability and cognitive functions assessed with sMMT in geriatric population with well-controlled BP.

CONCLUSION

The increased blood pressure variability was associated with poorer cognitive functions in geriatric hypertensive patients with well-controlled blood pressure.

Hypertension and Cognitive Decline: Implications of Obstructive Sleep Apnea

Hypertension and dementia are highly prevalent in the general population. Hypertension has been shown to be a risk factor for Alzheimer's dementia and vascular dementia. Sleep apnea, another common disorder, is strongly associated with hypertension and recent evidence suggests that it may also be linked with cognitive decline and dementia. It is possible that sleep apnea is the final common pathway linking hypertension to the development of dementia. This hypothesis merits further exploration as sleep apnea is readily treatable and such therapy could foreseeably delay or prevent the onset of dementia. At present, there is a paucity of therapeutic modalities that can prevent or arrest cognitive decline. In this review, we describe the associations between hypertension, dementia and sleep apnea, the pathophysiologic mechanisms underlying these associations, and the literature examining the impact of treatment of hypertension and sleep apnea on cognition. Potential areas of future investigation that may help advance our understanding of the magnitude and direction of the interaction between these conditions and the effects of treatment of high blood pressure and sleep apnea on cognition are highlighted.

Blood Pressure Circadian Variation, Cognition and Brain Imaging in 90+ Year-Olds

Purpose: To analyze the relationship between blood pressure (BP) variables, including circadian pattern, and cognition in 90+ year-olds.

Methods: Twenty-four hour ambulatory BP monitoring was completed on 121 participants drawn from a longitudinal study of aging and dementia in the oldest-old. Various measures of BP and its variability, including nocturnal dipping, were calculated. Each person was given both a neuropsychological test battery covering different cognitive domains and a neurological examination to determine cognitive status. Seventy-one participants had a brain magnetic resonance imaging (MRI) scan.

Results: Participants ranged in age from 90 to 102 years (mean = 93), about two-thirds were female, and nearly 80% had at least some college education. Mean nocturnal dips differed significantly between cognitively normal (n = 97) and impaired individuals (n = 24), with cognitively normal participants having on average greater nocturnal dips [6.6% vs. 1.3%, p = 0.006 for systolic BP (SBP); 11% vs. 4.4%, p = 0.002 for diastolic BP (DBP)]. Nocturnal dips were also related to performance on select cognitive test scores (especially those related to language, recent memory and visual-spatial ability), with individuals who performed below previously established median norms having significantly smaller nocturnal dips (both SBP and DBP) than those above the median. DBP reverse dippers had larger mean white matter hyperintensities (WMH as percent of total brain volume; 1.7% vs. 1.2%, 1.1% and 1.0% in extreme dippers, dippers, non-dippers) and a greater proportion had lobar cerebral microbleeds (CMBs; 44% vs. 0%, 7%, 16%, p < 0.05). Impaired participants had higher mean WMH than those with normal cognition (1.6% vs. 1.0% p = 0.03) and more tended to have CMB (31% vs. 20%, p = n.s.).

Conclusion: These findings suggest that cognitive dysfunction is associated with dysregulation in the normal circadian BP pattern. Further study is warranted of the potential role of WHM and CMB as mediators of this association.

Ambulatory blood pressure monitoring and neurocognitive function in children with primary hypertension

BACKGROUND

Children with primary hypertension have been reported to have diminished scores in measures of cognition. However, little is known about the relative correlation between office and ambulatory blood pressure (BP) and neurocognitive test performance, and whether short-term BP variability is associated with decreased neurocognitive function. We sought to determine whether ambulatory BP monitoring (ABPM) was more strongly associated with neurocognitive test performance compared with office BP, and whether increased short-term BP variability was associated with lower neurocognitive scores.

METHODS

Seventy-five subjects ages 10-18 years, with untreated primary hypertension, and 75 matched normotensive controls completed neurocognitive testing. All subjects had office BP and ABPM prior to neurocognitive testing.

RESULTS

On multivariate analyses, there was no significant association between office BP and neurocognitive tests. However, several ABPM parameters were significantly associated with neurocognitive test scores in the lower quartile, in particular 24 h SBP load and wake systolic blood pressure (SBP) index [Rey Auditory Verbal learning Test (RAVLT) List A Trial 1, 24 h SBP load, odds ratio (OR) = 1.02, wake SBP index, OR = 1.06; List A Total, 24 h SBP load, OR = 1.02, wake SBP index, OR = 1.06; Short Delay Recall, wake SBP index, OR = 1.06; CogState Maze delayed recall, 24 h SBP load, OR = 1.03, wake SBP index, OR = 1.08; Grooved Pegboard, 24 h SBP load, OR = 1.02; all p < 0.05]. In contrast, short-term BP variability measures were not associated with neurocognitive test performance.

CONCLUSIONS

ABPM is superior to office BP in distinguishing hypertensive youth with lower neurocognitive test performance.

[Cognitive functions, emotional status, MRI measurements in treatment-naïve middle-aged patients with uncomplicated essential arterial hypertension]

AIM

To study cognitive functions, anxiety and depression levels, 24-hour blood pressure (BP) profile, cerebral blood flow (CBF) perfusion in treatment-naive middle-aged patients with uncomplicated essential arterial hypertension (EAH) depending on the white matter hyperintensities (WMH) burden.

MATERIAL AND METHODS

Forty-one hypertensive patients (mean age 46.2±4.6 years) and 41 healthy volunteers (mean age 50.3±6.7 years) were enrolled to the study. All subjects underwent brain MRI (MAGNETOM Skyra 3.0T, T1, T2 FSE, T2 FLAIR, T1 MPRAGE, ASL), Montreal cognitive assessment (MoCa), 10-word learning task, verbal fluency test, trail making test, Stroop color and word test, anxiety and depression assessment with Hamilton rating scales, 24-hour blood pressure monitoring (ABPM).

RESULTS

WMH were found in 22 (53.7%) hypertensive patients and in 3 (7.3%) healthy volunteers (p=0.0002). Hypertensive patients had the significantly lower CBF compared to controls (p<0.001).

CONCLUSION

WMH were identified in treatment-naive middle-aged patients with uncomplicated mild to moderate EAH. There was an association between WMH and lower CBF in the cortical plate of frontal lobes, SBP variability and worse cognition. Cerebral hypoperfusion can cause cognitive impairment even in the earliest stages of EAH, which increases due to emotional disorders.

Early differentiation of dementia with Lewy bodies and Alzheimer's disease: Heart rate variability at mild cognitive impairment stage

OBJECTIVE

Our study aimed to investigate whether heart rate variability (HRV) could be a useful diagnostic screening tool at MCI (mild cognitive impairment) stage of Dementia with Lewy bodies (DLB) from Alzheimer's disease (AD).

METHODS

This retrospective study used a selected sample from Ajou neurological registry. We identified MCI patients who underwent HRV testing at baseline, and who developed probable DLB (MCI-DLB: n = 23) or AD (MCI-AD: n = 32).

RESULTS

The MCI-DLB group exhibited significantly lower levels of almost all HRV parameters compared with the MCI-AD group. Fronto-executive function and visuospatial abilities were poorer in the MCI-DLB group, whereas the extent of verbal memory impairment was greater in the MCI-AD. Verbal memory score was negatively correlated with overall HRV parameters, and visuospatial function was positively correlated with the frequency domain of HRV. Receiver operating curve area under the curve (AUC) analysis revealed that the low frequency component was the best potential diagnostic marker (AUC = 0.88).

CONCLUSION

MCI-DLB patients exhibited greater cardiac autonomic dysfunction (as measured by HRV) and greater fronto-executive and visuospatial deficit compared with MCI-AD patients.

SIGNIFICANCE

HRV may be useful method to differentiate DLB from AD in patients with MCI; this would facilitate early disease-specific intervention.

Exaggerated blood pressure variability is associated with memory impairment in very elderly patients

We investigated the association between working memory (WM) impairment and blood pressure variability (BPV) in very elderly patients. Japanese outpatients ≥80 years who engaged in normal activities of daily living were the study cohort. WM function was evaluated by a simple visual WM test consisting of 3 figures. We considered the number of figures recalled by the patient his/her test score. We defined the patients with a score of 0 or 1 as those with WM impairment and those with scores of 2 or 3 as those without. To investigate the relative risk of WM impairment, we evaluated each patient's 24 hour ambulatory systolic blood pressure (SBP) and its weighted standard deviation (SD_SBP ), office SBP, and the visit-to-visit SD_SBP during the 1 year period from the patient's enrollment. A total of 66 patients (mean 84 ± 3.6 years) showed WM impairment, and 431 patients (mean 83 ± 3.1 years) showed no WM impairment. There were no significant differences in 24 hour ambulatory SBP or office SBP between these two groups. However, the WM impairment patients showed significantly higher weighted SD_SBP and visit-to-visit SD_SBP values compared to the no-impairment group even after adjusting for age. Among these ≥80-year-old patients, those with the highest quartile of both weighted SD_SBP (≥21.4 mm Hg) and visit-to-visit SD_SBP (≥14.5 mm Hg) showed the highest relative risk (odds ratio 3.52, 95% confidence interval 1.42-8.72) for WM impairment. Exaggerated blood pressure variability parameters were significantly associated with working memory impairment in very elderly individuals.

Blood Pressure Variability and Cognitive Function Among Older African Americans: Introducing a New Blood Pressure Variability Measure

BACKGROUND

Although blood pressure (BP) variability has been reported to be associated with cognitive impairment, whether this relationship affects African Americans has been unclear. We sought correlations between systolic and diastolic BP variability and cognitive function in community-dwelling older African Americans, and introduced a new BP variability measure that can be applied to BP data collected in clinical practice.

METHODS

We assessed cognitive function in 94 cognitively normal older African Americans using the Mini-Mental State Examination (MMSE) and the Computer Assessment of Mild Cognitive Impairment (CAMCI). We used BP measurements taken at the patients' three most recent primary care clinic visits to generate three traditional BP variability indices, range, standard deviation, and coefficient of variation, plus a new index, random slope, which accounts for unequal BP measurement intervals within and across patients.

RESULTS

MMSE scores did not correlate with any of the BP variability indices. Patients with greater diastolic BP variability were less accurate on the CAMCI verbal memory and incidental memory tasks. Results were similar across the four BP variability indices.

CONCLUSIONS

In a sample of cognitively intact older African American adults, BP variability did not correlate with global cognitive function, as measured by the MMSE. However, higher diastolic BP variability correlated with poorer verbal and incidental memory. By accounting for differences in BP measurement intervals, our new BP variability index may help alert primary care physicians to patients at particular risk for cognitive decline.

Relationship Between Blood Pressure Variability and Cognitive Function in Elderly Patients With Good Blood Pressure Control

BACKGROUND

Although higher blood pressure (BP) levels and BP variability have been associated with cognitive impairment, data are sparse regarding the relationship between BP variability and cognitive function in elderly patients with well BP control.

METHODS

We analyzed 232 ambulatory patients with one or more cardiovascular risk factors. All patients underwent ambulatory BP monitoring and the Japanese version of the Montreal Cognitive Assessment (MoCA-J).

RESULTS

The mean age was 77.7 ± 8.3 years; 33.6% were male, and 85.3% were taking antihypertensive drugs. The average 24-hour BP level was 118.7 ± 10.0/68.3 ± 6.4 mm Hg. When we divided the weighted SD of systolic BP (SBP) as a measure of BP variability into quartiles, the top quartile group (≥19.6 mm Hg) had a significantly lower total MoCA-J score (15.4 [95% confidence interval 14.2-16.7] vs. 17.9 [17.2-18.6], P = 0.001) and lower scores on several domains, visuoexecutive (2.2 [1.9-2.6] vs. 2.8 [2.6-2.9], P = 0.012), abstraction (1.0 [0.7-1.2] vs. 1.3 [1.1-1.4], P = 0.015), attention (2.8 [2.4-3.1] vs. 3.6 [3.4-3.8], P = 0.001), and naming (2.1 [1.9-2.3] vs. 2.5 [2.4-2.6], P = 0.001) than quartiles 1 through 3 combined, after adjustment for age and 24-hour SBP. These associations were not found in the quartiles of 24-hour SBP.

CONCLUSIONS

In elderly patients with well ambulatory BP control, higher BP variability but not average ambulatory BP level was associated with cognitive impairment.

Heart Rate Variability and Cognitive Function In Middle-Age Adults: The Coronary Artery Risk Development in Young Adults

BACKGROUND

Low heart rate variability (HRV), a marker of cardiac autonomic dysfunction, has been associated with major risk factors of cognitive impairment. Yet, the direct association of HRV with cognitive function remains relatively unexplored, particularly in midlife.

METHODS

In 2005, 2 measures of short-term HRV, the SD of normal-to-normal intervals (SDNN) and the root mean square of successive differences (RMSSD), were calculated for participants of the Coronary Artery Risk Development in Young Adults study, and then categorized into quartiles. Five years later, 3 cognitive tests were administered for verbal memory ("Rey Auditory-Verbal Learning Test", RAVLT, range 0-15), processing speed ("Digit Symbol Substitution Test", DSST, range 0-133), and executive function ("Stroop interference").

RESULTS

Two thousand one hundred and eighteen participants (57.7% female, 42.2% Black) with a mean baseline age of 45.3 years were included in this analysis. In demographic-adjusted models, compared to participants with quartile 1 SDNN (lowest quartile), participants in the upper quartiles of SDNN scored better on the DSST (quartile 4: β = 1.83 points better, P = 0.03; and quartile 3: β = 1.95 points better, P = 0.03) and on the stroop (quartile 3: β = 1.19 points better, P < 0.05; and quartile2: β = 1.44 points better, P = 0.02). After adjusting for behavioral and cardiovascular risk factors, higher quartile SDNN remained significantly associated with better stroop score (quartile 3: β = 1.21 points better, P = 0.04; and quartile 2: β = 1.72 points better, P < 0.01) but not with DSST. There was no association between quartile of RMSSD and cognitive function, from fully adjusted models.

CONCLUSIONS

Our findings suggest that higher quartile SDDN is associated with better executive function in midlife, above, and beyond cardiovascular risk factors.

Associations of Nocturnal Blood Pressure With Cognition by Self-Identified Race in Middle-Aged and Older Adults: The GENOA (Genetic Epidemiology Network of Arteriopathy) Study

Background

Whether the association of blood pressure (BP) during sleep (nocturnal BP) with cognition differs by race is unknown.

Methods and Results

Participants in the GENOA (Genetic Epidemiology Network of Arteriopathy) Study underwent ambulatory BP measurements, brain magnetic resonance imaging, and cognitive function testing (the Rey Auditory Verbal Learning Test, the Digit Symbol Substitution Task, and the Trail Making Test Part B) between 2000 and 2007. We examined multivariable linear regression models of the nocturnal BP‐cognition association. Among 755 participants (mean age, 63 years; 64% women; 42% self‐identified black race; 76% taking antihypertensive medication), mean nocturnal systolic BP (SBP)/diastolic BP was 126/69 mm Hg, daytime SBP/diastolic BP level was 139/82 mm Hg, and mean reduction in SBP from day to night (dipping) was 9%. Among the entire sample, a race interaction was observed in Digit Symbol Substitution Task and Trail Making Test Part B (both P<0.15). Race‐stratified analyses showed that a 1‐SD increase in nocturnal SBP levels was associated with poorer Digit Symbol Substitution Task and log‐transformed Trail Making Test Part B scores (unstandardized regression coefficient [95% confidence interval]: −1.98 [−3.28 to −0.69] and 0.06 [0.004–0.12]; both P<0.05) in black but not white individuals. Additional adjustments for white matter hyperintensity volumes or brain atrophy, measured via brain magnetic resonance imaging, did not change the results. Results were similar when nocturnal SBP dipping was assessed as the exposure, yet daytime SBP levels yielded no association with cognition.

Conclusions

Nocturnal SBP measurements may be useful in assessing the potential risk for lower cognitive function in middle‐aged and older adults, particularly in black individuals.

Blood pressure variability and cognitive decline in older people: a 5-year longitudinal study

BACKGROUND

Cognitive impairment is common in later life. Identifying potential modifiable risk factors for cognitive decline may ameliorate the burden of disease. Cross-sectional studies show an association between blood pressure (BP) variability and impaired cognitive function in patients with hypertension and/or dementia. However, research examining the association between BP variability and cognitive function in the general older population is scarce.

OBJECTIVE

In this study, we examined the association between BP variability and cognitive function over 5-year follow-up in an unselected community-dwelling cohort.

METHODS

Ambulatory BP monitoring was performed in 353 community-dwelling people aged at least 65 years. Cognitive assessment, using the Mini Mental State Examination (MMSE) and Cambridge Cognitive Examination (CAMCOG), was performed at baseline and at 5-year follow-up. BP variability was calculated using the coefficient of variation. Cognitive change over 5 years was defined as baseline score minus follow-up score.

RESULTS

Increased daytime systolic variability was associated with poorer performance on the CAMCOG total score and subscores. Daytime diastolic variability was associated with poorer performance on total CAMCOG, CAMCOG executive score, and MMSE. These findings were independent of demographic and cardiovascular risk factors. Daytime systolic variability was also independently associated with greater decline in total CAMCOG and MMSE scores over 5-year follow-up.

CONCLUSION

Increased BP variability is associated with poorer cognitive function in older people and may represent a novel modifiable risk factor for cognitive decline.

Defining the Relationship Between Hypertension, Cognitive Decline, and Dementia: a Review

Hypertension is a highly prevalent condition which has been established as a risk factor for cardiovascular and cerebrovascular disease. Although the understanding of the relationship between cardiocirculatory dysfunction and brain health has improved significantly over the last several decades, it is still unclear whether hypertension constitutes a potentially treatable risk factor for cognitive decline and dementia. While it is clear that hypertension can affect brain structure and function, recent findings suggest that the associations between blood pressure and brain health are complex and, in many cases, dependent on factors such as age, hypertension chronicity, and antihypertensive medication use. Whereas large epidemiological studies have demonstrated a consistent association between high midlife BP and late-life cognitive decline and incident dementia, associations between late-life blood pressure and cognition have been less consistent. Recent evidence suggests that hypertension may promote alterations in brain structure and function through a process of cerebral vessel remodeling, which can lead to disruptions in cerebral autoregulation, reductions in cerebral perfusion, and limit the brain's ability to clear potentially harmful proteins such as β-amyloid. The purpose of the current review is to synthesize recent findings from epidemiological, neuroimaging, physiological, genetic, and translational research to provide an overview of what is currently known about the association between blood pressure and cognitive function across the lifespan. In doing so, the current review also discusses the results of recent randomized controlled trials of antihypertensive therapy to reduce cognitive decline, highlights several methodological limitations, and provides recommendations for future clinical trial design.

"Do it-yourself": Home blood pressure as a predictor of traditional and everyday cognition in older adults

BACKGROUND

Hypertension guidelines recommend home blood pressure (HBP) monitoring in adjunct to office blood pressure (OBP) for its greater reproducibility and prognostic utility in the prevention of cardiovascular outcomes, especially stroke. To date, the relationship between HBP and cognitive function remains unexplored.

METHODS

We examined HBP as a cognitive predictor in a multi-ethnic group of community-dwelling adults aged 60 and over (N = 133) using neuropsychological measures and analyzed the data using multiple regression analyses. We also employed "everyday cognition" measures that have been found to have higher prognostic utility for real-world functioning than traditional cognitive tasks.

RESULTS

Good to perfect HBP monitoring compliance over seven days was achieved by 88.7% of the participants with superior reliability (ICC≥.96) to office readings. Higher home systolic BP and pulse pressure predicted worse processing speed, executive function, and everyday cognitive function, whereas lower home diastolic BP predicted worse everyday cognition. Office readings were similarly associated with everyday cognitive function but with no other cognitive measures.

CONCLUSION

Our findings are the first to validate HBP as a predictor of neuropsychological function in older adults beyond cognitive screening. Differential relationships among blood pressure variables and specific cognitive domains were observed. With proper standardization and training, we demonstrated that HBP can be obtained in a multi-ethnic community-dwelling older adult cohort. Our findings emphasize the importance of employing blood pressure and cognitive measures that are adequately sensitive to detect vascular-related cognitive impairment in a relatively healthy population. Implications regarding proper HBP measurement for hypertension management, cognitive health, and everyday function are discussed.

Relationship Between 24-Hour Ambulatory Blood Pressure and Cognitive Function in Community-Living Older Adults: The UCSD Ambulatory Blood Pressure Study

BACKGROUND

Twenty-four-hour ambulatory blood pressure (BP) patterns have been associated with diminished cognitive function in hypertensive and very elderly populations. The relationship between ambulatory BP patterns and cognitive function in community-living older adults is unknown.

METHODS

We conducted a cross-sectional study in which 24-hour ambulatory BP, in-clinic BP, and cognitive function measures were obtained from 319 community-living older adults.

RESULTS

The mean age was 72 years, 66% were female, and 13% were African-American. We performed linear regression with performance on the Montreal Cognitive Assessment (MoCA) as the primary outcome and 24-hour BP patterns as the independent variable, adjusting for age, sex, race/ethnicity, education, and comorbidities. Greater nighttime systolic dipping (P = 0.046) and higher 24-hour diastolic BP (DBP; P = 0.015) were both significantly associated with better cognitive function, whereas 24-hour systolic BP (SBP), average real variability, and ambulatory arterial stiffness were not.

CONCLUSIONS

Higher 24-hour DBP and greater nighttime systolic dipping were significantly associated with improved cognitive function. Future studies should examine whether low 24-hour DBP and lack of nighttime systolic dipping predict future cognitive impairment.

Spectral analyses of systolic blood pressure and heart rate variability and their association with cognitive performance in elderly hypertensive subjects

Systolic hypertension is associated with cognitive decline in the elderly. Altered blood pressure (BP) variability is a possible mechanism of reduced cognitive performance in elderly hypertensives. We hypothesized that altered beat-to-beat systolic BP variability is associated with reduced global cognitive performance in elderly hypertensive subjects. In exploratory analyses, we also studied the correlation between diverse discrete cognitive domains and indices of systolic BP and heart rate variability. Disproving our initial hypothesis, we have shown that hypertension and low education, but not indices of systolic BP and heart rate variability, were independent predictors of lower global cognitive performance. However, exploratory analyses showed that the systolic BP variability in semi-upright position was an independent predictor of matrix reasoning (B = 0.08 ± .03, P-value = 0.005), whereas heart rate variability in semi-upright position was an independent predictor of the executive function score (B = -6.36 ± 2.55, P-value = 0.02). We conclude that myogenic vascular and sympathetic modulation of systolic BP do not contribute to reduced global cognitive performance in treated hypertensive subjects. Nevertheless, our results suggest that both systolic BP and heart rate variability might be associated with modulation of frontal lobe cognitive domains, such as executive function and matrix reasoning.

Ambulatory blood pressure in stroke and cognitive dysfunction

We have reviewed the most relevant data regarding ABPM and brain damage, with specific reference to first and recurrent stroke, silent structural brain lesions such as lacunar infarcts and white matter lesions, and cognitive impairment. Only two large studies have evaluated the usefulness of ABPM in relation to antihypertensive treatment in primary stroke prevention. In the Syst-Eur trial, drug treatment reduced ABPM and office BP more than placebo in patients with sustained isolated systolic hypertension (ISH). In contrast, in those patients with white-coat hypertension (WCH) changes in ABPM between the treatment groups were not significantly different. Patients with WCH had a lower incidence of stroke (p < 0.05) during follow-up than patients with sustained ISH, suggesting that WCH is a benign condition. In the HYVET trial 50 % of the very elderly patients included with office systolic BP > 160 mmHg had WCH. However, a significant 30 % stroke reduction was observed in treated patients including those with WCH, indicating that WCH may not be a benign condition in the elderly. In the acute stroke setting, where treatment of hypertension is not routinely recommended due to the lack of evidence and the differing results of the very few available trials, ABPM data shows that sustained high BP during the first 24 h after acute stroke is related to the formation of cerebral edema and a poorer functional status. On the other hand, even when nondipping status was initially related to a poorer prognosis, data indicate that patients with very-large nocturnal dipping, the so-called "extreme dippers", are those with the worse outcomes after stroke. The association between different ABPM parameters (circadian pattern, short-term variability) and poorer performance scores in cognitive function tests have been reported, especially in elderly hypertensives. Unfortunately most of these studies were cross-sectional and the associations do not establish causality.

The evidence for treating hypertension in older people with dementia: a systematic review

Hypertension and dementia commonly co-exist in older people, yet guidance is lacking on how to manage these co-existing conditions. The aim of this systematic review was to assess the evidence for the treatment of hypertension in older people with dementia. Medline, EMBASE, Cochrane Library and the national research register archives were searched. Inclusion criteria were: randomised controlled trial of hypertension treatment, included participants aged 65+ years, participants had a diagnosis of dementia (global cognitive decline for at least 6 months affecting daily function), and the study assessed cognitive outcomes using validated tools. Dementia prevention studies and poor quality studies were excluded. The initial search revealed 1178 papers of potential interest, of which 24 were selected for review and six met the full inclusion criteria. Trials included people with mild-to-moderate but not severe dementia; exclusion criteria for the trials were extensive. Four trials were placebo-controlled RCTs; the remaining two compared different antihypertensives. All trials reported MMSE scores at baseline and follow-up; four reported blood pressure changes at follow-up; and only three reported cardiovascular morbidity or mortality at follow-up. Only one of four placebo-controlled studies showed evidence of blood pressure reduction, but no clear evidence for benefit (or harm) from antihypertensives on cognition, physical function or other cardiovascular outcomes. We found no evidence to confirm or refute the hypothesis that treatment of hypertension in people with dementia leads to overall health benefit.

Reduced heart rate variability is associated with worse cognitive performance in elderly Mexican Americans

Reduced heart rate variability is a strong predictor of cardiovascular risk factors, cardiovascular events, and mortality and thus may be associated with cognitive neurodegeneration. Yet, this has been relatively unexplored, particularly in minority populations with high cardiovascular burden. We used data from the Sacramento Area Latino Study on Aging to examine the cross-sectional association of reduced heart rate variability with cognitive function among elderly Mexican Americans. A total of 869 participants (mean age, 75 years; 59% women) had their 6-minute heart rate variability measured using an ECG monitor and respiration pacer in response to deep breathing. We used the mean circular resultant, known as R bar, as a measure of heart rate variability and categorized it into quartiles (Q1 to Q4 of R bar: reduced to high heart rate variability). Cognitive function was assessed using the modified Mini-Mental State Examination, a 100-point test of global cognitive function, and the Spanish and English verbal learning test, a 15-point test of verbal memory recall. In fully adjusted linear regression models, participants in quartile 1 had a 4-point lower modified Mini-Mental State Examination score (P<0.01), those in quartile 2 had a 2-point lower score (P=0.04), and those in quartile 3 had a 1-point lower score (P=0.35) compared with those in the highest quartile of R bar. Reduced R bar was not associated with verbal memory. Our results suggest that reduced heart rate variability is associated with worse performance on the test of global cognitive function, above and beyond traditional cardiovascular risk factors.

Midlife hypertensive status and cognitive function 20 years later: the Southall and Brent revisited study

Objectives: To investigate long-term prospective associations between a range of measurements of hypertensive status in midlife and cognitive impairment 20 years later.

Design: Cohort study.

Setting: Two areas (Southall and Brent) of northwest London.

Participants: Survey samples of a multiethnic population (European, African Caribbean, South Asian) aged 40 to 67 were followed up 20 years later.

Measurements: Comprehensive cardiovascular assessments were performed at baseline, including measurements of resting blood pressure (BP) and, in a subsample, ambulatory BP. At follow-up, a battery of cognitive assessments was administered, and a composite outcome was derived, with impairment defined as the lowest 10% within each ethnic group. Logistic regression models were used to investigate associations with prior measures of hypertensive status.

Results: In 1,484 participants at follow-up, cognitive impairment showed significant U-shaped associations with baseline diastolic BP (DBP) and mean arterial pressure (MAP; strongest for those aged ≥50 at baseline), independent of a range of covariates, but no associations were found with systolic BP or pulse pressure. Cognitive impairment was also associated with antihypertensive medication use and higher evening ambulatory DBP at baseline. No substantial differences in strengths of association were found between ethnic groups.

Conclusion: Low and high DBP and MAP were associated with cognitive impairment 20 years later. Higher evening DBP on ambulatory monitoring was also associated with greater risk.

Hypertension and mild cognitive impairment

The brain is an early target for organ damage due to high blood pressure. Hypertension is the major modifiable risk factor for stroke and small vessel disease. It has been suggested that cerebral microvascular disease contributes to vascular cognitive impairment. The mechanisms underlying hypertension-related cognitive changes are complex and not yet fully understood. Both high and, especially in the elderly, low blood pressure (BP) have been linked to cognitive decline and dementia. There is some evidence that antihypertensive drug treatment could play a role in the prevention of cognitive impairment through BP control. The BP levels that should be targeted to achieve optimal perfusion while preventing cognitive decline are still under debate.

Ambulatory blood pressure monitoring in the elderly

The incidence of hypertension is high in the elderly and is present in 2/3 of the patients older than 65 years. Prevalence can reach 90% in patients older than 80 years. The presence of isolated systolic hypertension (ISH) is characteristic of this population. However, the prevalence of hypertension by ambulatory blood pressure monitoring (ABPM) is not well known. In this study, we analyzed the special characteristics of hypertension in this population, giving special emphasis on ABPM readings.

Does blood pressure variability modulate cardiovascular risk?

Exactly how hypertension causes end organ damage and vascular events is poorly understood. Yet the concept that underlying "usual" blood pressure (BP) accounts for all BP-related risk of vascular events and for the benefits of BP-lowering drugs has come to underpin clinical guidelines on the diagnosis and treatment of hypertension. This article reviews evidence that variability in BP also predicts risk of stroke and other vascular events independently of mean BP and evidence that drug-class effects on variability in BP explain differences in the effectiveness of BP-lowering drugs in preventing stroke.

Associations between self-assessed masticatory ability and higher brain function among the elderly

Among the elderly, the quality of higher brain function is a contributing factor in performing activities of daily living. The aim of the study is to elucidate, epidemiologically, associations between mastication and higher brain function. A total of 208 community-dwelling elderly persons, aged 70-74 years, were enrolled. Self-assessed masticatory ability (masticatory ability) was classified into one of three categories: ability to chew all kinds of food, ability to chew only slightly hard food, or ability to chew only soft or pureed food. Brain function was assessed by four neuropsychological tests: Raven's Colored Progressive Matrices (RCPM) test, the Verbal Paired Associates 1 (VerPA) task and the Visual Paired Associates 1 task (from the Wechsler Memory Scale Revised Edition), and the Block Design subtest (from the Wechsler Adult Intelligence Scales-Third Edition). Correlations between masticatory ability and each test were examined using Spearman rank correlation coefficients. Multinominal logistic regression models were conducted with the neuropsychological tests as the dependent variables and masticatory ability as the principal independent variable to adjust for age, gender, educational background, social activity, drinking/smoking habits, chronic medical conditions and dental status. Significant correlations were found between the RCPM test, the VerPA task, the Block Design test and masticatory ability. In multinominal logistic regression models, poor masticatory ability was significantly and independently related to the categories under the mean-s.d. points compared with those of the mean ± s.d. ranges for RCPM test and the VerPA task. Significant associations may exist between mastication and higher brain function among the elderly.

Nondipping phenomenon and quality of life: are they related in essential hypertensive patients?

Hypertensive patients report lower general well-being, more severe psychological distress, poorer perceived health status, more physical symptoms, and functional disability when compared to normotensive patients. Nondipping of blood pressure (BP) is related to increased target organ damage in essential hypertension. However, the specific relationship between nocturnal nondipping and quality of life has not been extensively investigated. Patients with essential hypertension underwent the following procedures: anamnesis, office BP measurement, physical examination, routine biochemistry, and 24-hour ambulatory BP monitoring. To determine renal function, 24-hour urine specimens were collected. Quality of life was assessed by a short form of medical outcomes study (SF-36). Totally, 132 patients (male/female: 55/75) were included. Fifty-five of the patients were nondippers. The dippers and nondippers were not statistically different in terms of socio-demographic parameters. Dippers had higher physical functioning (P- 0.004), bodily pain (P- 0.008), and PCS (P - 0.003) than nondippers. PCS of SF-36 was independently associated with age (P - 0.029), body mass index (P - 0.022), presence of coronary artery disease (P - 0.01), gender (P - 0.009), and dipping phenomenon (P - 0.006). A mental component summary score of SF-36 was not associated with dipping phenomenon. Nocturnal nondipping, apart from having important prognostic implications for cardiovascular complications in essential hypertensive patients, is also related to quality of life, especially in its physical aspects.

Hypertension and dementia

Although hypertension is well known as a cause of vascular dementia (VaD), recent findings highlight the role of hypertension in the pathogenesis of Alzheimer's disease (AD) as well as mild cognitive impairment (MCI). Recent studies have shown that disruption of diurnal blood pressure (BP) variation is closely associated with cognitive impairment via injury of the small cerebral arteries indicating that long-standing hypertension constitutes a risk of brain matter atrophy or white matter lesions (WMLs). In several clinical trials, BP-lowering with antihypertensive agents was suggested to reduce the risk of dementia or cognitive decline. This review paper focuses on the role of hypertension as a risk factor for cognitive impairment, and summarizes current knowledge on the relationships between ambulatory BP monitoring (ABPM) and cognitive impairment. Finally, an overview of the impact of antihypertensive therapy on dementia prevention is provided.

Blood pressure and cognitive function in older adults with cardiovascular disease

BACKGROUND

Past studies link elevated blood pressure (BP) and BP variability to adverse neurocognitive changes in community samples. However, little is known about the relationship between BP indices and cognitive function in older CVD patients.

METHODS

A total of 99 older adults with CVD completed a comprehensive neuropsychological test battery. Resting BP measurements were collected every 10 min for 2 hr during a separate cardiac assessment. Five BP indices were generated: average and standard deviation of systolic blood pressure (SBP), average and standard deviation of diastolic blood pressure (DBP), and a function of systolic variability and average diastolic pressure. We examined the relationship between these BP indices and cognitive function.

RESULTS

Partial correlation adjusting for age and education revealed that the function of systolic variability and average diastolic pressure (SBP standard deviation divided by the average DBP) was most closely related to test performance, showing significant associations to both Learning/Memory (r = 0.25) and Language functioning (r = 0.22). SBP indices were also related to Language functioning (SBP avg., r = 0.22; SBP SD, r = 0.25), though DBP indices were unrelated to performance in any cognitive domain.

CONCLUSIONS

The current findings indicate that BP is modestly related to cognitive function in older CVD patients. Contrary to expectations, greater BP variability was associated with better, not poorer, cognitive test performance. Such findings suggest that the relationship between BP and cognitive function is more complicated than typically believed and requires further examination.

The relationship between nighttime dipping in blood pressure and cerebral hemodynamics in nonstroke patients

Inadequate dipping in nighttime blood pressure (BP) is associated with cerebrovascular disease. The authors aimed to determine whether inadequate nocturnal dipping was associated with abnormalities in cerebrovascular hemodynamics in individuals without stroke. Participants in this study underwent 24-hour ambulatory BP monitoring followed by morning transcranial Doppler measurements of blood flow velocities (BFVs) in the middle cerebral artery during supine rest, head-up tilt, hypocapnia, and hypercapnia. Nighttime BP decline by <10% was considered nondipping. Of the 102 nonstroke participants (mean age, 53.6 years), 35 (34%) were dippers. Although nondippers had similar BFV and cerebrovascular resistance (CVR) while supine, they had a lower BFV (P=.04) and greater CVR (P=.02) during head-up tilt compared with dippers. Moreover, greater nighttime dipping in both systolic BP (P=.006) and diastolic BP (P=.03) were associated with higher daytime BFV and lower CVR (P=.01 for systolic BP; P=.02 for diastolic BP). Inadequate nocturnal BP dipping is associated with lower daytime cerebral blood flow, especially during head-up tilt.

Blood Pressure Variability and Dementia Rating Scale Performance in Older Adults With Cardiovascular Disease

OBJECTIVE

The present study examined the relationship between multiple indices of blood pressure (BP) and cognitive function (as measured by the Dementia Rating Scale).

BACKGROUND

Cardiovascular disease (CVD) is associated with cognitive dysfunction and cerebrovascular pathology in the elderly and is a known risk factor for stroke and Alzheimer disease. Yet, the mechanisms for the effects of CVD on cognitive function are not well understood.

METHODS

Participants were 97 nondemented older adults with CVD who underwent neuropsychologic assessment, and a 2-hour cardiovascular laboratory protocol.

RESULTS

After controlling for age and years of education, results of hierarchical linear regression analyses indicate a significant positive relationship between a function of BP variability (SD of systolic BP divided by the average diastolic BP) and cognitive function (R change=0.042, F (1, 85)=5.434, P<0.05). No relationship emerged between any other BP index and cognitive function.

CONCLUSIONS

Contrary to expectations, greater BP variability was associated with better, not poorer, cognitive test performance. These findings suggest that the relationship between BP and cognitive function is more complicated than originally conceptualized and requires further investigation.

Association between reduced heart rate variability and cognitive impairment in older disabled women in the community: Women's Health and Aging Study I

OBJECTIVES

To examine the independent association between heart rate variability (HRV), a marker of cardiac autonomic function, and cognitive impairment.

DESIGN

Cross-sectional analysis of baseline data from Women's Health and Aging Study I.

SETTING

Urban community in Baltimore, Maryland.

PARTICIPANTS

A subset of 311 physically disabled, community-dwelling women aged 65 and older whose HRV data were obtained.

MEASUREMENTS

Reduced HRV was defined as the lowest quartile of each of several HRV measures exploring time and frequency domains and compared with the remaining three quartiles. Cognitive impairment was defined as a Mini-Mental State Examination score less than 24. Multiple logistic regression was used to model the independent relationship between reduced HRV and prevalent cognitive impairment.

RESULTS

The age-, education-, and race-adjusted prevalence of cognitive impairment was higher in those with reduced HRV than in those with nonreduced HRV. After adjusting for relevant demographic and clinical characteristics, participants with reduced HRV were significantly more likely than those with nonreduced HRV to have cognitive impairment; these findings were consistent across different HRV indices. In particular, reduced high-frequency power, indicative of decreased parasympathetic activity, was associated with 6.7 times greater odds of cognitive impairment (95% confidence interval = 2.27-20.0).

CONCLUSION

Cardiac autonomic dysfunction, particularly decreased parasympathetic activity, was independently associated with cognitive impairment in older disabled women in the community. This finding may improve understanding of the pathophysiological basis of cognitive impairment. The potential role of HRV as a cause or consequence of cognitive impairment needs to be elucidated in future studies.

Higher Plasma Homocysteine Concentration Is Associated with More Advanced Systemic Arterial Stiffness and Greater Blood Pressure Response to Stress in Hypertensive Patients

Hyperhomocysteinemia has been reported to be associated with both vascular structure alteration and increased cardiovascular risk. This study examined whether hyperhomocysteinemia causes increased systemic arterial stiffness, thereby enhancing blood pressure response to stress in hypertensive patients. In 50 treated hypertensive patients, we studied brachial-ankle pulse wave velocity (PWV), a new measure for arterial stiffness, blood pressure response to stress, and blood pressure recovery after stress. Autonomic nervous activities were examined by spectral analysis of blood pressure and RR interval variabilities. Total plasma homocysteine and neurohumoral parameters were determined from fasting blood. Brachial-ankle PWV correlated with age (r=0.64, p<0.001), plasma homocysteine concentration (r=0.35, p<0.05), and systolic blood pressure (SBP) (r=0.62, p<0.001). Higher plasma homocysteine concentration was independently associated with greater brachial-ankle PWV (beta=0.388, p=0.01). We classified the subjects into high homocysteine (7.3 nmol/ml or over) and low homocysteine (7.2 nmol/ml or below) groups. Baseline SBP, plasma renin activity, aldosterone, and norepinephrine concentrations were similar between the two groups. However, the SBP values during stress and the recovery periods were higher in the high homocysteine group than the low homocysteine group even after adjusting for sex and age. The behavior of sympathetic vasomotor activity did not differ between the two groups. These data suggest that higher plasma homocysteine concentration is associated with increased systemic arterial stiffness, which may enhance blood pressure reactivity to stress in hypertensive patients.

Cerebral white matter blood flow is constant during human non-rapid eye movement sleep: a positron emission tomographic study

This study aimed to identify brain regions with the least decreased cerebral blood flow (CBF) and their relationship to physiological parameters during human non-rapid eye movement (NREM) sleep. Using [15O]H2O positron emission tomography, CBF was measured for nine normal young adults during nighttime. As NREM sleep progressed, mean arterial blood pressure and whole brain mean CBF decreased significantly; arterial partial pressure of CO2 and, selectively, relative CBF of the cerebral white matter increased significantly. Absolute CBF remained constant in the cerebral white matter, registering 25.9 ± 3.8 during wakefulness, 25.8 ± 3.3 during light NREM sleep, and 26.9 ± 3.0 (ml·100 g−1·min−1) during deep NREM sleep ( P = 0.592), and in the occipital cortex ( P = 0.611). The regression slope of the absolute CBF significantly differed with respect to arterial partial pressure of CO2 between the cerebral white matter (slope 0.054, R = − 0.04) and frontoparietal association cortex (slope − 0.776, R = − 0.31) ( P = 0.005) or thalamus (slope − 1.933, R = − 0.47) ( P = 0.004) and between the occipital cortex (slope 0.084, R = 0.06) and frontoparietal association cortex ( P = 0.021) or thalamus ( P < 0.001), and, with respect to mean arterial blood pressure, between the cerebral white matter (slope − 0.067, R = − 0.10) and thalamus (slope 0.637, R = 0.31) ( P = 0.044). The cerebral white matter CBF keeps constant during NREM sleep as well as the occipital cortical CBF, and may be specifically regulated by both CO2 vasoreactivity and pressure autoregulation.