Essential hypotension is accompanied by deficits in attention and working memory

The cardiac, vasomotor and myocardial branches of the baroreflex in hypotension: indications of reduced venous return to the heart

PURPOSE

Alterations of autonomic cardiovascular control are implicated in the origin of chronic low blood pressure (BP) (hypotension), but comprehensive analysis of baroreflex function is still lacking. This study explored baroreflex function in its cardiac, vascular and myocardial branches METHODS: Continuous BP was recorded at rest and during a mental arithmetic task in 40 hypotensive and 40 normotensive participants. Assessed cardiovascular variables included stroke volume (SV) (calculated by the Modelflow method), heart rate (HR), cardiac output (CO), total peripheral resistance (TPR) and heart rate variability (HRV). Baroreflex sensitivity (BRS) was calculated using the spontaneous sequence method.

RESULTS

Hypotensive participants exhibited greater BRS in the three baroreflex branches, in addition to lower SV, HR and CO and higher HRV and TPR. Reactivity for BP, HRV and CO during the stress task was reduced in hypotensive individuals. The greater cardiac BRS can explain the lower HR and higher HRV observed in hypotension, suggestive of increased vagal cardiac influences. The higher vasomotor BRS may contribute to the greater TPR observed in the hypotensive participants. Abnormal associations between myocardial BRS and SV arose, suggesting aberrant autonomic control of myocardial contractility in hypotension.

CONCLUSION

The results indicate that hemodynamic deficits in hypotension are related to preload factors, probably triggered by hypovolemia and reduced unstressed blood reserves, resulting in lower venous return, ventricular preload and SV. In contrast, afterload mechanisms seem to work appropriately.

A single bout of aerobic exercise does not alter inhibitory control preparatory set cerebral hemodynamics: Evidence from the antisaccade task

A single bout of exercise improves executive function (EF) and is a benefit - in part -attributed to an exercise-mediated increase in cerebral blood flow enhancing neural efficiency. Limited work has used an event-related protocol to examine postexercise changes in preparatory phase cerebral hemodynamics for an EF task. This is salient given the neural efficiency hypothesis' assertion that improved EF is related to decreased brain activity. Here, event-related transcranial Doppler ultrasound was used to measure pro- (saccade to target) and antisaccades (saccade mirror-symmetrical target) preparatory phase middle cerebral artery velocity (MCAv) prior to and immediately after 15-min of aerobic exercise. Antisaccades produced longer reaction times (RT) and an increased preparatory phase MCAv than prosaccades - a result attributed to greater EF neural activity for antisaccades. Antisaccades selectively produced a postexercise RT reduction (ps < 0.01); however, antisaccade preparatory phase MCAv did not vary from pre- to postexercise (p=0.53) and did not correlate with the antisaccade RT benefit (p = 0.31). Accordingly, results provide no evidence that improved neural efficiency indexed via functional hyperemia is linked to a postexercise EF behavioural benefit. Instead, results support an evolving view that an EF benefit represents the additive interplay between interdependent exercise-mediated neurophysiological changes.

Hypotension with neurovascular changes and cognitive dysfunction: An epidemiological, pathobiological, and treatment review

ABSTRACT

Hypotension is a leading cause of age-related cognitive impairment. The available literature evidences that vascular factors are associated with dementia and that hypotension alters cerebral perfusion flow and can aggravate the neurodegeneration of Alzheimer's disease (AD). Despite the discovery of biomarkers and the recent progress made in neurovascular biology, epidemiology, and brain imaging, some key issues remain largely unresolved: the potential mechanisms underlying the neural deterioration observed in AD, the effect of cerebrovascular alterations on cognitive deficits, and the positive effects of hypotension treatment on cognition. Therefore, further well-designed studies are needed to unravel the potential association between hypotension and cognitive dysfunction and reveal the potential benefits of hypotension treatment for AD patients. Here, we review the current epidemiological, pathobiological, and treatment-related literature on neurovascular changes and hypotension-related cognitive dysfunction and highlight the unsettled but imminent issues that warrant future research endeavors.

Relations of Metabolic Health and Obesity to Brain Aging in Young to Middle-Aged Adults

Background We aimed to evaluate the association between metabolic health and obesity and brain health measured via magnetic resonance imaging and neurocognitive testing in community dwelling adults. Methods and Results Framingham Heart Study Third Generation Cohort members (n=2170, 46±9 years of age, 54% women) without prevalent diabetes, stroke, dementia, or other neurologic conditions were grouped by metabolic unhealthiness (≥2 criteria for metabolic syndrome) and obesity (body mass index ≥30 kg/m2): metabolically healthy (MH) nonobese, MH obese, metabolically unhealthy (MU) nonobese, and MU obese. We evaluated the relationships of these groups with brain structure (magnetic resonance imaging) and function (neurocognitive tests). In multivariable-adjusted analyses, metabolically unhealthy individuals (MU nonobese and MU obese) had lower total cerebral brain volume compared with the MH nonobese referent group (both P<0.05). Additionally, the MU obese group had greater white matter hyperintensity volume (P=0.004), whereas no association was noted between white matter hyperintensity volume and either groups of metabolic health or obesity alone. Obese individuals had less favorable cognitive scores: MH obese had lower scores on global cognition, Logical Memory-Delayed Recall and Similarities tests, and MU obese had lower scores on Similarities and Visual Reproductions-Delayed tests (all P≤0.04). MU and obese groups had higher free water content and lower fractional anisotropy in several brain regions, consistent with loss of white matter integrity. Conclusions In this cross-sectional cohort study of younger to middle-aged adults, poor metabolic health and obesity were associated with structural and functional evidence of brain aging. Improvement in metabolic health and obesity may present opportunities to improve long-term brain health.

Blood Pressure and Risk of Cognitive Impairment: The Role of Vascular Disease in Neurodegeneration

(1) Background: Both cerebral vascular disorders and cognitive decline increase in incidence with age. The role of cerebral vascular disease and hemodynamic changes in the development of cognitive deficits is controversial. The objective of this study was to assess the cardiovascular response during cardiac stress testing in neurologically asymptomatic individuals who developed cognitive impairment several years after previous cardiac stress testing. (2) Methods: This was a retrospective cohort study of patients who underwent cardiac stress testing between January 2001 and December 2010. Patients were followed up until May 2015, and we selected those who developed cognitive dysfunction including dementia, mild cognitive impairment, and subjective cognitive decline, after the stress test. Heart rate and blood pressure both at rest and at peak exercise, and the mean R-R interval at rest were recorded. For each patient who developed cognitive impairment, we selected one matched control who did not show cognitive decline by the end of the follow-up period. (3) Results: From the cohort of 7224 patients, 371 developed cognitive impairment; of these, 186 (124 men) met the inclusion criteria, and 186 of the other patients were selected as matched controls. During follow-up, cognitive impairment appeared 6.2 ± 4.7 years after the cardiac stress test. These patients who had subsequently developed cognitive impairment had significantly lower at-rest systolic, diastolic, and mean blood pressure than controls (p < 0.05). Further, compared with controls, their maximum heart rate was significantly higher at peak exercise. (4) Conclusion: The results from this study suggest that differences in cardiovascular response to stress might be present in individuals who develop cognitive decline. These findings challenge the possibility of assessing blood pressure and heart rate variability at rest and during cardiac stress as potential risk factors associated with cognitive impairment.

Baroreceptor Modulation of the Cardiovascular System, Pain, Consciousness, and Cognition

Baroreceptors are mechanosensitive elements of the peripheral nervous system that maintain cardiovascular homeostasis by coordinating the responses to external and internal environmental stressors. While it is well known that carotid and cardiopulmonary baroreceptors modulate sympathetic vasomotor and parasympathetic cardiac neural autonomic drive, to avoid excessive fluctuations in vascular tone and maintain intravascular volume, there is increasing recognition that baroreceptors also modulate a wide range of non-cardiovascular physiological responses via projections from the nucleus of the solitary tract to regions of the central nervous system, including the spinal cord. These projections regulate pain perception, sleep, consciousness, and cognition. In this article, we summarize the physiology of baroreceptor pathways and responses to baroreceptor activation with an emphasis on the mechanisms influencing cardiovascular function, pain perception, consciousness, and cognition. Understanding baroreceptor-mediated effects on cardiac and extra-cardiac autonomic activities will further our understanding of the pathophysiology of multiple common clinical conditions, such as chronic pain, disorders of consciousness (e.g., abnormalities in sleep-wake), and cognitive impairment, which may result in the identification and implementation of novel treatment modalities. © 2021 American Physiological Society. Compr Physiol 11:1373-1423, 2021.

Multidimensional review of cognitive impairment after spinal cord injury

Cognitive impairment is highly prevalent in the population with spinal cord injury (SCI) and exerts a significant impact on functional independence and quality of life in this population. A number of neuroscientists have conducted preliminary investigations of cognitive deficits after SCI, but achieved marginally contradictory results due to some limitations such as the heterogeneity in the sample population, sample size, types of tests utilized, study design, and time since SCI. Therefore, this review mainly focuses on the characteristics, assessments, potential causality and treatment of cognitive impairment for better understanding such deficits in the SCI population.

Association between the variability of cerebral oxygen saturation during cardiopulmonary bypass and delayed postoperative neurocognitive recovery in cardiac valve surgical patients: A pilot study

AIMS OF THE STUDY

The association between regional cerebral oxygen saturation (rSO2) and postoperative cognitive decline is controversial. In this study, we investigated the association between the real variability of regional cerebral oxygen saturation during cardiopulmonary bypass (CPB) and postoperative delayed neurocognitive recovery in patients undergoing heart valve surgery.

METHODS USED TO CONDUCT THE STUDY

A total of 71 patients who underwent cardiac valve surgery were enrolled in this study. Patients were assessed for cognitive function using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment Scale (MOCA) on the day before surgery and the 7th day after surgery. The real variability of regional cerebral oxygen saturation (rSO2), real variability of the brain bispectral index of EEG (BIS), real variability of mean arterial pressure (MAP) and body temperature were monitored during CPB. Patients were divided into two groups according to neural cognitive function scores to explore the relationship between postoperative delayed neurocognitive recovery and the real variability of cerebral oxygen saturation, BIS, MAP, and body temperature during CPB.

RESULTS OF THE STUDY

Twenty-seven patients were diagnosed with postoperative delayed neurocognitive recovery. The occurrence of postoperative delayed neurocognitive recovery after surgery was closely related to the large variability of rSO2 during the rewarming phase of CPB (P < .05). Logistic analysis showed that preoperative arrhythmia, a lower level of serum albumin after surgery and greater rSO2 variability during the rewarming phase were risk factors for postoperative delayed neurocognitive recovery (P < .05). In this study, there was no correlation between postoperative delayed neurocognitive recovery and BIS, MAP or body temperature variability (P > .05).

CONCLUSIONS DRAWN FROM THE STUDY AND CLINICAL IMPLICATIONS

The real variability of rSO2 during the CPB rewarming phase was related to postoperative delayed neurocognitive recovery in patients who underwent cardiac surgery.

CHA2DS2-VASc scores and Intermountain Mortality Risk Scores for the joint risk stratification of dementia among patients with atrial fibrillation

BACKGROUND

High CHA₂DS₂-VASc scores in atrial fibrillation (AF) patients are generally associated with increased risks of stroke and dementia. At lower CHA₂DS₂-VASc scores, there remains an unquantifiable cranial injury risk, necessitating an improved risk assessment method within these lower-risk groups.

OBJECTIVE

The purpose of this study was to determine whether sex-specific Intermountain Mortality Risk Scores (IMRS), a dynamic measures of systemic health that comprises commonly performed blood tests, can stratify dementia risk overall and among CHA₂DS₂-VASc score strata in AF patients.

METHODS

Female (n = 34,083) and male (n = 39,998) AF patients with no history of dementia were studied. CHA₂DS₂-VASc scores were assessed at the time of AF diagnosis and were stratified into scores of 0-1, 2, and ≥3. Within each CHA₂DS₂-VASc score stratum, patients were further stratified by IMRS categories of low, moderate, and high. Multivariable Cox hazard regression was used to determine dementia risk.

RESULTS

High-risk IMRS patients were generally older and had higher rates of hypertension, diabetes, heart failure, and prior stroke. Higher CHA₂DS₂-VASc score strata (≥3 vs ≤1: women, hazard ratio [HR] 7.77, 95% confidence interval [CI] 5.94-10.17, P < .001; men: HR 4.75, 95% CI 4.15-5.44, P < .001) and IMRS categories (high vs low: women, HR 3.09, 95% CI 2.71-3.51, P < .001; men, HR 2.70, 95% CI 2.39-3.06, P < .001) were predictive of dementia. When stratified by CHA₂DS₂-VASc scores, IMRS further identified risk in each stratum.

CONCLUSION

Both CHA₂DS₂-VASc scores and IMRS were independently associated with dementia incidence among AF patients. IMRS further stratified dementia risk among CHA₂DS₂-VASc score strata, particularly among those with lower CHA₂DS₂-VASc scores.

Features of autonomic cardiovascular control during cognition in major depressive disorder

Previous research has suggested reduced parasympathetic cardiac regulation during cognitive activity in major depressive disorder (MDD). However, little is known about possible abnormalities in sympathetic control and cardiovascular reactivity. This study aimed to provide a comprehensive analysis of autonomic cardiovascular control in the context of executive functions in MDD. Thirty six MDD patients and 39 healthy controls participated. Parameters of sympathetic (pre-ejection period, PEP) and parasympathetic control (high and low frequency heart rate variability, HF HRV, LF HRV; and baroreflex sensitivity, BRS) as well as RR interval were obtained at rest and during performance of executive function tasks (number-letter task, n-back task, continuous performance test, and Stroop task). Patients, as compared to controls, exhibited lower HF HRV and LF HRV during task execution and smaller shortenings in PEP and RR interval between baseline and tasks. They displayed longer reaction times during all conditions of the tasks and more omission errors and false alarms on the continuous performance test. In the total sample, on-task HF HRV, LF HRV and BRS, and reactivity in HF HRV, LF HRV, and PEP, were positively associated with task performance. As performance reduction arose independent of executive function load of the tasks, the behavioral results reflect impairments in attention and processing speed rather than executive dysfunctions in MDD. Abnormalities in cardiovascular control during cognition in MDD appear to involve both divisions of the autonomic nervous system. Low tonic parasympathetic control and blunted sympathetic reactivity imply reduced physiological adjustment resources and, by extension, provide suboptimal conditions for cognitive performance.

Depressive Symptoms and Blood Pressure

Abstract. In the present investigation it is hypothesized that depressive symptoms and antidepressant therapy are associated with systolic and diastolic blood pressure. Moreover, in additional analyses, the interaction effects of age, gender, and depressive symptoms are estimated, and discussed in the context of previous findings. Data from the German Health Interview and Examination Survey for Adults (DEGS1) were analyzed ( N = 7,987) by means of multi-response Bayesian hierarchical regression models. Missing data were imputed by the method of chain equations. Independent variables included depressive symptoms, antidepressant medication, gender, age, smoking, physical activity, family history of hypertension, body mass index, and antihypertensive medication. The estimates obtained in the multi-response model revealed that depressive symptoms were negatively associated with arterial blood pressure (−0.09, 99% CI [−0.147; −0.040]). Antidepressant therapy was found to be positively associated with increased blood pressure (1.035, 99% CI [0.333; 1.990]). There were negative interaction effects of depressive symptoms and age among women only (−0.006 99% CI [−0.010; −0.001]). The results agree with previous findings reporting a negative association between depressive symptoms and blood pressure. In addition, regarding the trajectory of blood pressure across the lifespan, interaction effects of depressive symptoms and age were found among females. The results indicate a linear increase in blood pressure with increasing age which, however, tends to flatten and decrease by around age 55 in both males and females. Potential physiological mechanisms may be related to affect regulation taking place at higher levels of cognitive processing and affecting blood pressure regulation, and/or cardiovascular mechanisms related to cerebral blood flow, arterial blood pressure, and depressive symptoms which have not been sufficiently explained so far.

Diverse cognitive impairment after spinal cord injury is associated with orthostatic hypotension symptom burden

This study: 1) compared cognitive functioning between individuals with chronic (>1 year) spinal cord injury (SCI) and non-injured controls and, 2) assessed associations between symptoms of autonomic dysreflexia and orthostatic hypotension with cognitive functioning in SCI participants with a history of unstable blood pressure (BP). Thirty-two individuals with SCI (C4-L2, American Spinal Injury Association Impairment Scale A-D) and thirty age, sex-matched non-injured controls participated in this study. Participants completed a motor-free neuropsychological test battery assessing 1) memory, 2) attention/concentration/psychomotor speed and, 3) executive function. Nineteen participants with SCI who had injuries ≥T6 and a history of unstable BP also completed the Autonomic Dysfunction Following Spinal Cord Injury (ADFSCI) questionnaire. Cognitive function was significantly lower in people with SCI across measures of memory and executive function compared to non-injured controls. Significant, moderate-to-large associations were observed between cumulative (frequency x severity) orthostatic hypotension and total BP instability symptoms scores, with measures of attention/concentration/psychomotor speed and executive function. These data demonstrate a 10 - 65% reduced performance across specific realms of cognitive functioning in individuals with SCI relative to non-injured controls. Furthermore, cumulative subjective scores for symptoms of unstable BP were associated with diverse cognitive deficits. These findings, in individuals without co-occurring traumatic brain injury, imply cardiovascular dysregulation plays a role in cognitive deficits observed in this population.

Cardiovascular autonomic profile in women with constitutional hypotension

BACKGROUND

Constitutional hypotension (CHT) is defined as a SBP below 105 mmHg. As autonomic-related symptoms are frequently reported in CHT, these symptoms suggest that the cardiovascular autonomic control is perturbed in individuals with CHT.

METHODS

We investigated the autonomic cardiovascular control of 15 women with CHT and 12 women with NBP (SBP >110 mmHg). We monitored BP and ECG for autonomic function test. Supine and head up tilt (HUT) spectral analysis of RR interval and BP variability, baroreflex sensitivity and plasma levels of plasma renin activity and aldosterone were determined. M-mode echocardiogram was used to determine the left ventricle mass.

RESULTS

SBP and DBP were lower in CHT (97 ± 1.5 and 54 ± 1.5 mmHg) than in NBP (126 ± 3 and 70 ± 4 mmHg, P < 0.001 for both), whereas heart rate was comparable (65 ± 1.5 and 63 ± 3 bpm). CHT compared with NBP had lower Valsalva's ratio and BP phase IV overshooting, 1.7 ± 0.07 vs. 2 ± 0.07 (P < 0.05) and 19 ± 2.4, and 28 ± 3 mmHg (P < 0.05), respectively. BRSseq, alpha LF and LFRR/HFRR were greater in CHT (29.2 ± 0.7 and 39.1 ± 4.7 ms/mmHg and 1.4 ± 0.2) compared with NBP (25 ± 1.6 and 20.1 ± 2.5 ms/mmHg and 0.7 ± 01, [P < 05, for all]). LFSAP was lower in CHT (0.8 ± 0.2) than in NBP (1.5 ± 0.3 mmHg, P < 0.02). HUT data were similar. Supine and HUT aldosterone and PRA were higher in CHT. Left ventricle mass was lower in CHT.

CONCLUSION

We conclude that the cardiovascular autonomic control in women with CHT is characterized by a low sympathetic vascular tone and increased baroreceptor sensitivity. Also, it seems that these women have a compensated primary hypovolemia, which warrants further investigation.

The Blood Pressure Pendulum following Spinal Cord Injury: Implications for Vascular Cognitive Impairment

Cognitive impairment following spinal cord injury (SCI) has received considerable attention in recent years. Among the various systemic effects of SCI that contribute towards cognitive decline in this population, cardiovascular dysfunction is arguably one of the most significant. The majority of individuals with a cervical or upper-thoracic SCI commonly experience conditions called orthostatic hypotension and autonomic dysreflexia, which are characterized by dangerous fluctuations in systemic blood pressure (BP). Herein, we review the potential impact of extreme BP lability on vascular cognitive impairment (VCI) in individuals with SCI. Albeit preliminary in the SCI population, there is convincing evidence that chronic hypotension and hypertension in able-bodied individuals results in devastating impairments in cerebrovascular health, leading to VCI. We discuss the pertinent literature, and while drawing mechanistic comparisons between able-bodied cohorts and individuals with SCI, we emphasize the need for additional research to elucidate the mechanisms of cognitive impairment specific to the SCI population. Lastly, we highlight the current and potential future therapies to manage and treat BP instability, thereby possibly mitigating VCI in the SCI population.

Autonomic Cardiovascular Dysregulation at Rest and During Stress in Chronically Low Blood Pressure

Abstract. Chronic low blood pressure (hypotension) is accompanied by symptoms such as fatigue, reduced drive, faintness, dizziness, cold limbs, and concentration difficulties. The study explored the involvement of aberrances in autonomic cardiovascular control in the origin of this condition. In 40 hypotensive and 40 normotensive subjects, impedance cardiography, electrocardiography, and continuous blood pressure recordings were performed at rest and during stress induced by mental calculation. Parameters of cardiac sympathetic control (i.e., stroke volume, cardiac output, pre-ejection period, total peripheral resistance), parasympathetic control (i.e., heart rate variability), and baroreflex function (i.e., baroreflex sensitivity) were obtained. The hypotensive group exhibited markedly lower stroke volume, heart rate, and cardiac output, as well as higher pre-ejection period and baroreflex sensitivity than the control group. Hypotension was furthermore associated with a smaller blood pressure response during stress. No group differences arose in total peripheral resistance and heart rate variability. While reduced beta-adrenergic myocardial drive seems to constitute the principal feature of the autonomic impairment that characterizes chronic hypotension, baroreflex-related mechanisms may also contribute to this state. Insufficient organ perfusion due to reduced cardiac output and deficient cardiovascular adjustment to situational requirements may be involved in the manifestation of bodily and mental symptoms.

Cerebral blood flow modulations during antisaccade preparation in chronic hypotension

In addition to symptoms including fatigue, dizziness, reduced drive, or mood disturbance, individuals with chronic low blood pressure (hypotension) frequently report cognitive complaints. While attentional deficits have been empirically confirmed, it is still unknown whether the impairments also encompass executive functions. This study investigated cerebral blood flow modulations in hypotension during a precued antisaccade/prosaccade task requiring the executive function of proactive inhibition in addition to preparatory attention. Using functional transcranial Doppler sonography, bilateral blood flow velocities in the middle cerebral arteries (MCA) were recorded in 39 hypotensive and 40 normotensive participants. In the task, a stimulus appeared left or right of a fixation point 5 s after a cuing stimulus; subjects had to move their gaze to the mirror image position of the stimulus (antisaccade) or toward it (prosaccade control condition). Video-based eye tracking was used for ocular recording. A right dominant MCA blood flow increase arose during task preparation, which was smaller in hypotensive than normotensive participants. In addition, hypotensive participants exhibited lower peak velocity of the saccadic response. The extent of the reductions in blood flow and task performance in hypotension did not differ between antisaccade and prosaccade conditions. The smaller MCA flow increase may reflect reduced activity in the dorsolateral prefrontal and inferior parietal cortices during proactive inhibition and preparatory attention in hypotension. Given that group differences in blood flow and performance arose independent of task complexity and executive function load, hypotension may be characterized by basic attentional impairments rather than particular executive function deficits.

Dysfunction of Cerebrovascular Endothelial Cells: Prelude to Vascular Dementia

Vascular dementia (VaD) is the second most common type of dementia after Alzheimer's disease (AD), characterized by progressive cognitive impairment, memory loss, and thinking or speech problems. VaD is usually caused by cerebrovascular disease, during which, cerebrovascular endothelial cells (CECs) are vulnerable. CEC dysfunction occurs before the onset of VaD and can eventually lead to dysregulation of cerebral blood flow and blood-brain barrier damage, followed by the activation of glia and inflammatory environment in the brain. White matter, neuronal axons, and synapses are compromised in this process, leading to cognitive impairment. The present review summarizes the mechanisms underlying CEC impairment during hypoperfusion and pathological role of CECs in VaD. Through the comprehensive examination and summarization, endothelial nitric oxide synthase (eNOS)/nitric oxide (NO) signaling pathway, Ras homolog gene family member A (RhoA) signaling pathway, and CEC-derived caveolin-1 (CAV-1) are proposed to serve as targets of new drugs for the treatment of VaD.

Cognitive function after spinal cord injury: A systematic review

OBJECTIVE

To systematically examine the incidence of cognitive impairment in individuals with spinal cord injury (SCI), as well as identify potential contributing and confounding factors.

METHODS

Studies quantitatively reporting cognitive ability after spinal cord injury were searched electronically via Medline, CINAHL, Embase, and PsycINFO. Manual screening for references within articles was also performed. A total of 2,481 studies were screened and a total of 70 were included in this review, 21 reporting cognitive function after SCI compared to an able-bodied control group and 49 with no able-bodied controls. Studies were analyzed for the incidence of impairment and the interactions with concomitant traumatic brain injury, psychological or somatic complaints, decentralized cardiovascular control, sleep apnea, neurologic level of injury, and age.

RESULTS

There is a high volume of evidence reporting substantial cognitive impairment in individuals with SCI. Potential co-contributors include concomitant brain injury, psychological or somatic comorbidities, decentralized cardiovascular control, and sleep apnea. Cognitive functioning was negatively correlated with age. No clear agreement was found for the incidence of cognitive impairment or its association with level of injury.

CONCLUSION

Current evidence suggests that individuals with SCI should be examined and addressed for cognitive impairment. Future studies aimed at identifying potential secondary causative factors should employ stringent controls for co-occurring brain trauma since it appears to be a major contributor and confounder to impaired cognition.

Cerebral blood flow modulations during proactive control in chronic hypotension

In addition to complaints including fatigue, mood disturbance, dizziness or cold limbs, chronic low blood pressure (hypotension) is associated with reduced cognitive performance. Deficiencies in cerebral blood flow regulation may contribute to this impairment. This study investigated cerebral blood flow modulations during proactive control in hypotension. Proactive control refers to cognitive processes during anticipation of a behaviourally relevant event that allow optimization of readiness to react. Using functional transcranial Doppler sonography, bilateral blood flow velocities in the middle cerebral arteries were recorded in 40 hypotensive and 40 normotensive participants during a precued Stroop task. Hypotensive participants exhibited smaller bilateral blood flow increases during response preparation and longer response time. The group differences in blood flow and response time did not vary by executive function load, i.e. congruent vs. incongruent trials. Over the total sample, the flow increase correlated negatively with response time in trials with a higher executive function load. The findings indicate reduced cerebral blood flow adjustment during both the basic and more complex requirements of proactive control in hypotension. They also suggest a general deficit in attentional function and processing speed due to low blood pressure and cerebral hemodynamic dysregulations rather than particular impairments in executive functions.

Atrial fibrillation incrementally increases dementia risk across all CHADS2 and CHA2DS2VASc strata in patients receiving long-term warfarin

BACKGROUND

Patients with atrial fibrillation (AF) are at higher risk for developing dementia. Warfarin is a common therapy for the prevention of thromboembolism in AF, valve replacement, and thrombosis patients. The extent to which AF itself increases dementia risk remains unknown.

METHODS

A total 6030 patients with no history of dementia and chronically anticoagulated with warfarin were studied. Warfarin management was provided through a Clinical Pharmacy Anticoagulation Service. Patients were stratified by warfarin indication of AF (n=3015) and non-AF (n=3015) and matched by propensity score (±0.01). Patients were stratified by the congestive heart failure, hypertension, age >75 years, diabetes, stroke (CHADS₂) score calculated at the time of warfarin initiation and followed for incident dementia.

RESULTS

The average age of the AF cohort was 69.3±11.2 years, and 52.7% were male; average age of non-AF cohort was 69.3±10.9 years, and 51.5% were male. Increasing CHADS₂ score was associated with increased dementia incidence, P trend=.004. When stratified by warfarin indication, AF patients had an increased risk of dementia incidence. After multivariable adjustment, AF patients continued to display a significantly increased risk of dementia when compared with non-AF patients across all CHADS₂ scores strata.

CONCLUSIONS

In patients receiving long-term warfarin therapy, dementia risk increased with increasing CHADS₂ scores. However, the presence of AF was associated with higher rates of dementia across all CHADS₂ score strata. These data suggest that AF contributes to the risk of dementia and that this risk is not solely attributable to anticoagulant use. Dementia may be an end manifestation of a systemic disease state, and AF likely contributes to its progression.

Cognitive impairment in COPD: should cognitive evaluation be part of respiratory assessment?

Cognitive impairment is highly prevalent in patients with COPD and demonstrates multiple detrimental effects on many aspects of patient state and therapeutic outcomes. It is attributed to several overlapping pathophysiological factors, with the most common being the low level of oxygen saturation due to respiratory insufficiency. Despite the impact of cognitive impairment on clinical outcomes, the screening for coexisting cognitive deficits which may interfere with the successful progress of respiratory treatment is yet neglected. There is a special consideration that cognitive deficits should be taken into account when developing respiratory therapy plans. Cognitively impaired patients are likely to require more support and have need of an individualised respiratory care plan which can also be beneficial for their cognitive deficits. Pulmonary rehabilitation as a multidisciplinary approach could be prioritised for COPD patients with cognitive impairment.

EDUCATIONAL AIMS

To illustrate the common signs of cognitive impairment and define potential associations between lung and cognitive dysfunction.To illustrate the potential influence of cognitive deficits on the optimal progress of respiratory therapy.To illustrate the importance of cognitive evaluation as part of a comprehensive clinical assessment for patients suspected of suffering cognitive impairment.

Affective impairment in chronic low blood pressure

OBJECTIVE

Physical complaints such as faintness, dizziness, cold limbs and headaches have been well-established in chronic low blood pressure (hypotension). This study investigated the occurrence of adverse emotional states and the symptoms of depression in this condition. As autonomic dysregulation, particularly diminished sympathetic tone, is believed to be involved in the etiology of hypotension, the impact of different facets of autonomic cardiovascular control on mood and depressive symptoms was also explored.

METHODS

Forty individuals with chronic hypotension and forty normotensive control persons were presented with the Mood Scale and Beck Depression Inventory. Stroke volume, cardiac output, pre-ejection period, Heather index and aortic peak blood flow velocity were recorded under resting conditions as indices of beta-adrenergic inotropic drive. Respiratory sinus arrhythmia and baroreflex sensitivity were additionally obtained.

RESULTS

Hypotensive individuals scored markedly higher on both questionnaire scales than controls, indicating an adversely affected emotional state and more severe depressive symptoms. In the entire sample, cardiac output, Heather index, and aortic peak blood flow velocity correlated negatively with the questionnaire scores; according to regression analysis, the Heather index explained the largest proportion of test score variance.

CONCLUSION

Although hypotension does not constitute a serious medical condition, the findings of an adverse affective state and increased burden with depressive symptoms corroborate the view that it can have a considerable impact on wellbeing and quality of life. The correlations of the beta-adrenergic indices with the questionnaire scales indicate that cardiac sympathetic regulation plays a key role in the psychophysiological mediation of hypotension-related mood impairment.

Fetal Alcohol Exposure Alters Blood Flow and Neurological Responses to Transient Cerebral Ischemia in Adult Mice

BACKGROUND

Prenatal alcohol exposure (PAE) can result in physical and neurocognitive deficits that are collectively termed "fetal alcohol spectrum disorders" (FASD). Although FASD is associated with lifelong intellectual disability, the mechanisms mediating the emergence of secondary mental health and physical disabilities are poorly understood. Based on our previous data showing that maternal ethanol (EtOH) exposure in mice resulted in an immediate reduction in cranially directed fetal blood flow, we hypothesized that such exposure would also result in persistent alterations in cranially directed blood flow in the prenatally alcohol-exposed (PAE) adult. We also hypothesized that PAE adults exposed to an acute cerebrovascular insult would exhibit more brain damage and neurobehavioral impairment compared to non-PAE adult controls.

METHODS

Pregnant C57BL/6 mice were exposed to EtOH, 3 g/kg, or water by intragastric gavage. Blood flow in carotid, renal, and femoral arteries was assessed by ultrasound imaging in PAE and control adults at 3, 6, and 12 months of age. To mimic ischemic stroke in young adult populations, 3-month-old PAE and control animals were subject to transient middle cerebral artery occlusion (MCAo) and subsequently assessed for behavioral recovery, stroke infarct volume, and brain cytokine profiles.

RESULTS

PAE resulted in a significant age-related decrease in blood acceleration in adult mice, specifically in the carotid artery. A unilateral transient MCAo resulted in equivalent cortico-striatal damage in both PAE and control adults. However, PAE adult mice exhibited significantly decreased poststroke behavioral recovery compared to controls.

CONCLUSIONS

Our data collectively show that PAE adult mice exhibit a persistent, long-term loss of cranially directed blood flow, and decreased capacity to compensate for brain trauma due to acute-onset adult diseases like ischemic stroke.

Drug-induced cognitive impairment: Effect of cardiovascular agents

INTRODUCTION

Cardiovascular agents can be associated with a negative effect on cognition, especially in older adults, critically ill people, and those with baseline cognitive impairment. Negative effect on cognition is commonly reported as uncomplicated acute confusion and delirium and, less commonly, chronic cognitive changes due to drug-induced depression and/or dementia.

METHODS

A literature review of case reports, case series, prospective cohort studies, clinical trials, and literature reviews were included in this study. Articles were located using online databases PubMed and Medline using the following keywords: antiarrhythmic agents, anticholinergic burden, antihypertensive agents, beta-blockers, cardiovascular agents, cognitive impairment, delirium, cognition, dementia, depression, digoxin, diuretics, and drug-induced cognitive impairment.

RESULTS

In general, use of all antihypertensives, especially in the case of polypharmacy or inappropriate dosing, can lead to hypotension and/or bradycardia, and thus lead to mental/cognitive status change due to decreased cerebral perfusion. Use of diuretics can be associated with fluid/electrolyte and/or acid-base imbalance, resulting in the onset of confusion and delirium. In addition, cardiovascular agents with central bioavailability, such digoxin and select antiarrhythmics, and antihypertensives may carry a risk for cognitive impairment due to various mechanisms proposed, such as antagonism of central muscarinic acetylcholine receptors, neurotransmission imbalance in the brain, and disruption of physiologic function of sodium/potassium ATPase in the neuronal cells.

DISCUSSION

When dealing with an individual who presents with acute, subacute, and chronic changes in cognitive function, one should perform a thorough medication history as the first step in order to aid in the identification of drug-induced cognitive impairment.

Age-Related Cognitive Impairment as a Sign of Geriatric Neurocardiovascular Interactions: May Polyphenols Play a Protective Role?

It is known that endothelial dysfunction plays an important role in the development and progression of cardiovascular diseases implicated also in cognitive decline. Experimental studies pointed to the fact that the modification of NO levels via NOS activity may affect the blood pressure level as well as several higher nervous functions—for example, learning and memory. There are emerging evidences from in vitro and animal studies suggesting that polyphenols may potentially have a protective effect on the development of neurodegenerative diseases and may improve cognitive function as well as positively affecting the blood pressure regulatory mechanisms. This review accentuates the need for precisely defined clinically controlled studies as well as for use of adequate experimental procedures discriminating between the human higher brain functions and the only overall activation of the brain cortex. The physiological neurocardiovascular interactions are implicated in the increased healthy life span as well.

An Exploratory Analysis of the Relationship between Cardiometabolic Risk Factors and Cognitive/Academic Performance among Adolescents

This exploratory study examines the relationship between cardiometabolic risk factors (blood pressure, waist circumference, BMI, and total cholesterol) and cognitive/academic performance. In this study, 1297 Taiwanese tenth-grade volunteers are recruited. Scores from the Basic Competency Test, an annual national competitive entrance examination, are used to evaluate academic performance. Cognitive abilities are accessed via the Multiple Aptitude Test Battery. The results indicate that systolic blood pressure is significantly, negatively associated with academic performance, both in male and female subjects. BMI and waist circumference are associated with verbal reasoning performance with an inverse U-shaped pattern, suggesting that both low and high BMI/waist circumference may be associated with lower verbal reasoning performance.

Prevalence of abnormal systemic hemodynamics in veterans with and without spinal cord injury

OBJECTIVE

Increased prevalence of heart rate and blood pressure abnormalities are evident in persons with spinal cord injury (SCI), but age, comorbid medical conditions, and prescription medication use may contribute. To determine differences in the prevalence of cardiac acceleration (heart rate ≥80 beats per minute), hypotension (blood pressure ≤110/70mmHg), orthostatic hypotension (OH) (-20/-10mmHg with upright positioning), and hypertension (HTN) (blood pressure ≥140/90mmHg) in veterans with and without SCI.

DESIGN

Observational trial.

SETTING

Medical center.

PARTICIPANTS

Subjects included veterans with SCI (n=62; cervical: tetraplegia, C3-8; high thoracic, T1-5; low thoracic, T7-L2) and veterans without SCI (n=160).

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

We assessed medical history, prescription medication use, and heart rate and blood pressure during a routine clinical visit. Prevalence rates of cardiac acceleration, hypotension, OH, and HTN were calculated using binary logistic regression analysis with 95% confidence intervals. The influence of SCI status, age, smoking status, cardiovascular diagnoses, and use of prescribed antihypertensive medications on the prevalence of abnormal heart rate and blood pressure recordings was determined.

RESULTS

The diagnosis of HTN was reduced in the high thoracic and tetraplegia groups compared with the non-SCI and low thoracic groups. Use of antihypertensive medications was increased in the low thoracic group compared with the other 3 groups and was increased in the non-SCI group compared with the tetraplegia group. The prevalence of cardiac acceleration was reduced, and the prevalence of systolic hypotension was increased in the tetraplegia group. The prevalence of diastolic hypotension was increased in all SCI groups compared with the non-SCI group. For all analyses, increased prevalence of abnormal heart rate and blood pressure recordings was not further explained by the covariates, with the exception of age, cardiovascular diagnoses, and antihypertensive medications in the cardiac acceleration model; however, SCI status remained significant and was the dominant predictor variable.

CONCLUSIONS

Our data suggest that SCI status contributes to the prevalence of cardiac acceleration and systolic and diastolic hypotension regardless of cardiovascular medical conditions or prescription antihypertensive medication use.

Diagnosing and treating neurogenic orthostatic hypotension in primary care

In response to a change in posture from supine or sitting to standing, autonomic reflexes normally maintain blood pressure (BP) by selective increases in arteriovenous resistance and by increased cardiac output, ensuring continued perfusion of the central nervous system. In neurogenic orthostatic hypotension (NOH), inadequate vasoconstriction and cardiac output cause BP to drop excessively, resulting in inadequate perfusion, with predictable symptoms such as dizziness, lightheadedness and falls. The condition may represent a central failure of baroreceptor signals to modulate cardiovascular function, a peripheral failure of norepinephrine release from cardiovascular sympathetic nerve endings, or both. Symptomatic patients may benefit from both non-pharmacologic and pharmacologic interventions. Among the latter, two pressor agents have been approved by the US Food and Drug Administration: the sympathomimetic prodrug midodrine, approved in 1996 for symptomatic orthostatic hypotension, and the norepinephrine prodrug droxidopa, approved in 2014, which is indicated for the treatment of symptomatic neurogenic orthostatic hypotension caused by primary autonomic failure (Parkinson's disease, multiple system atrophy and pure autonomic failure). A wide variety of off-label options also have been described (e.g. the synthetic mineralocorticoid fludrocortisone). Because pressor agents may promote supine hypertension, NOH management requires monitoring of supine BP and also lifestyle measures to minimize supine BP increases (e.g. head-of-bed elevation). However, NOH has been associated with cognitive impairment and increases a patient's risk of syncope and falls, with the potential for serious consequences. Hence, concerns about supine hypertension - for which the long-term prognosis in patients with NOH is yet to be established - must sometimes be balanced by the need to address a patient's immediate risks.

Orthostatic responses to anticholinesterase inhibition in spinal cord injury

INTRODUCTION

Acetylcholine (Ach) is the pre-synaptic neurotransmitter of the sympathetic nervous system. Increased pre-synaptic Ach may augment post-synaptic release of norepinephrine, thereby increasing systemic blood pressure (BP).

OBJECTIVES

The primary objective of this investigation was to determine the hemodynamic effect of pyridostigmine bromide (PYRIDO: 60 mg), an Ach inhibitor (AchI), compared to no-drug (NO-D) during head-up tilt (HUT) in individuals with spinal cord injury (SCI). Secondarily, we aimed to determine the effects of PYRIDO compared to NO-D on symptoms of orthostatic intolerance (OI) and adverse event reporting (AE).

METHODS

Ten individuals with SCI (C4-C7) were studied on two occasions: visit (1) NO-D and visit (2) PYRIDO. On each visit subjects underwent a progressive HUT maneuver to 15°, 25°, 35° for 5 min at each angle and 45 min at 45°. Supine and orthostatic heart rate (HR), systolic and diastolic BP (SBP and DBP), as well as monitored and symptoms of OI and AE were monitored and recorded.

RESULTS

Supine hemodynamics did not differ between the trials. The significant fall in SBP during the NO-D trial was diminished with PYRIDO, and five subjects had an increased DBP during HUT with PYRIDO compared to the NO-D trial. Individuals that responded to PYRIDO with an increase in orthostatic BP had significantly lower resting HR than non-responders (p < 0.01), which suggests increased levels of pre-synaptic Ach. Subjective symptoms of OI and AE reporting did not differ between the two trials.

CONCLUSIONS

These preliminary data suggest that PYRIDO is safe and may be effective at ameliorating the orthostatic fall in BP in select individuals with SCI.

Reduced cerebral and cardiovascular hemodynamics during sustained affective stimulation in young women with chronic low blood pressure

Although low blood pressure has been associated with lower affect and higher depressive symptoms in the elderly, the presence of possible impairment in emotional reactivity in chronic hypotensive individuals in early adulthood remains largely unexplored. Using a combination of transcranial Doppler sonography, beat-to-beat blood pressure recording and impedance cardiography we assessed central and peripheral hemodynamic changes in 15 undergraduate women with chronic hypotension (Age: 23.9 ± 2.7 years) and 15 normotensive controls (Age: 23.7 ± 3.1 years) during sustained exposure to pleasant, unpleasant and neutral pictures. Overall, systolic blood pressure (SBP) increased in normotensives and decreased in hypotensives during picture viewing as compared to baseline. Also, compared to normotensives, in hypotensives mean cerebral blood flow velocity increased to a lesser extent during the viewing of pleasant pictures and the magnitude of this increase was negatively associated with subjective emotional arousal. In addition, in hypotensives screening SBP was positively associated with valence rating of pleasant contents. These findings indicate a close association between chronic low blood pressure and reduced processing of pleasant stimuli in young adulthood.

Ambulatory blood pressure monitoring in spinal cord injury: clinical practicability

Trauma to the spinal cord often results not only in sensorimotor but also autonomic impairments. The loss of autonomic control over the cardiovascular system can cause profound blood pressure (BP) derangements in subjects with spinal cord injury (SCI) and may therefore lead to increased cardiovascular disease (CVD) risk in this population. The use of ambulatory blood pressure monitoring (ABPM) allows insights into circadian BP profiles, which have been shown to be of good prognostic value for cardiovascular morbidity and mortality in able-bodied subjects. Past studies in SCI subjects using ABPM have shown that alterations in circadian BP patterns are dependent on the spinal lesion level. Tetraplegic subjects with sensorimotor complete lesions have a decreased daytime arterial BP, loss of the physiological nocturnal BP dip, and higher circadian BP variability, including potentially life-threatening hypertensive episodes known as autonomic dysreflexia (AD), compared with paraplegic and able-bodied subjects. The proposed underlying mechanisms of these adverse BP alterations mainly are attributed to a lost or decreased central drive to sympathetic spinal preganglionic neurons controlling the heart and blood vessels. In addition, several maladaptive anatomical changes within the spinal cord and the periphery, as well as the general decrease of physical daily activity in SCI subjects, account for adverse BP changes. ABPM enables the identification of adverse BP profiles and the associated increased risk for CVD in SCI subjects. Concurrently, it also might provide a useful clinical tool to monitor improvements of AD and lost nocturnal dip after appropriate treatments in the SCI population.

A retrospective chart review of heart rate and blood pressure abnormalities in veterans with spinal cord injury

OBJECTIVE

Autonomic impairment may lead to increased prevalence of heart rate (HR) and blood pressure (BP) abnormalities in veterans with spinal cord injury (SCI). In addition, comorbid medical conditions and prescription medication use may influence these abnormalities, including bradycardia, and tachycardia, hypotension, hypertension as well as autonomic dysreflexia (AD), and orthostatic hypotension (OH).

DESIGN

A retrospective review of clinical and administrative datasets in veterans with SCI and compared the prevalence rates between clinical values and ICD-9 diagnostic codes in individuals with tetraplegia (T: C1-C8), high paraplegia (HP: T1-T6), and low paraplegia (LP: T7 and below).

RESULTS

The prevalence of clinical values indicative of a HR ≥ 80 beats per minute was higher in the HP compared to the LP and T groups. A systolic BP (SBP) ≤ 110 mmHg was more common in the T compared to the HP and LP groups, whereas the prevalence of a SBP ≥ 140 mmHg was increased in the LP compared to the HP and T groups. Diagnosis of hypertension was 39-60% whereas the diagnosis of hypotension was less than 1%. Diagnosis of AD and OH was highest in the T group, but remained below 10%, regardless of categorical lesion level. Antihypertensive medications were commonly prescribed (55%), and patients on these medications were less likely to have high BP. The odds ratio of higher SBP and DBP increased with age and body mass index (BMI).

CONCLUSION

In veterans with SCI, the prevalence of HR and BP abnormalities varied depending on level of lesion, age, BMI, and prescription medication use.

A prospective report on the prevalence of heart rate and blood pressure abnormalities in veterans with spinal cord injuries

OBJECTIVE

Decentralized autonomic cardiovascular regulation may lead to increased prevalence of heart rate (HR) and blood pressure (BP) abnormalities in veterans with SCI. In addition, comorbid medical conditions and prescription medication use may increase HR and BP abnormalities. These abnormalities include bradycardia, and tachycardia, hypotension, hypertension as well as autonomic dysreflexia and orthostatic hypotension; the prevalence of which is unknown.

DESIGN

HR and BP data were measured during a routine annual physical examination in 64 veterans with SCI. Measurements of HR and BP were recorded in the seated and supine positions to document the influence of body position and to document intra-subject variability in these assessments.

RESULTS

All subjects were chronically injured (20 ± 14 years), 33 subjects were tetraplegic (T: C3-C8), nine had high paraplegia (HP: T1-T6), and 22 had low paraplegia (LP: T7-L2). Regardless of position, the prevalence of bradycardia was increased in the T group, whereas prevalence of tachycardia was increased in the HP and LP groups. Systolic hypotension was more common in the T and HP groups than the LP group and positional effects were most evident in the T group. Systolic hypertension was comparable in the T and HP groups but was twice as prevalent in the LP group. Increased prevalence of individuals with three or more medical conditions and prescribed three or more medications which might influence HR and BP was observed.

CONCLUSION

Decentralized autonomic regulation, comorbid medical conditions, and prescription medication use in veterans with SCI result in HR and BP abnormalities; our data suggest that these abnormalities vary depending on the level of injury and orthostatic positioning.

Regulation of cerebral blood flow after spinal cord injury

Significant cardiovascular and autonomic dysfunction occurs after era spinal cord injury (SCI). Two major conditions arising from autonomic dysfunction are orthostatic hypotension and autonomic dysreflexia (i.e., severe acute hypertension). Effective regulation of cerebral blood flow (CBF) is essential to offset these drastic changes in cerebral perfusion pressure. In the context of orthostatic hypotension and autonomic dysreflexia, the purpose of this review is to critically examine the mechanisms underlying effective CBF after an SCI and propose future avenues for research. Although only 16 studies have examined CBF control in those with high-level SCI (above the sixth thoracic spinal segment), it appears that CBF regulation is markedly altered in this population. Cerebrovascular function comprises three major mechanisms: (1) cerebral autoregulation, (i.e., ΔCBF/Δ blood pressure); (2) cerebrovascular reactivity to changes in PaCO2 (i.e. ΔCBF/arterial gas concentration); and (3) neurovascular coupling (i.e., ΔCBF/Δ metabolic demand). While static cerebral autoregulation appears to be well maintained in high-level SCI, dynamic cerebral autoregulation, cerebrovascular reactivity, and neurovascular coupling appear to be markedly altered. Several adverse complications after high-level SCI may mediate the changes in CBF regulation including: systemic endothelial dysfunction, sleep apnea, dyslipidemia, decentralization of sympathetic control, and dominant parasympathetic activity. Future studies are needed to describe whether altered CBF responses after SCI aid or impede orthostatic tolerance. Further, simultaneous evaluation of extracranial and intracranial CBF, combined with modern structural and functional imaging, would allow for a more comprehensive evaluation of CBF regulatory processes. We are only beginning to understand the functional effects of dysfunctional CBF regulation on brain function on persons with SCI, which are likely to include increased risk of transient ischemic attacks, stroke, and cognitive dysfunction.

Blood pressure regulation IX: cerebral autoregulation under blood pressure challenges

Cerebral autoregulation (CA) is integral to the delicate process of maintaining stable cerebral perfusion and brain tissue oxygenation against changes in arterial blood pressure. The last four decades has seen dramatic advances in understanding CA physiology, and the role that CA might play in the causation and progression of disease processes that affect the cerebral circulation such as stroke. However, the translation of these basic scientific advances into clinical practice has been limited by the maintenance of old constructs and because there are persistent gaps in our understanding of how this vital vascular mechanism should be quantified. In this review, we re-evaluate relevant studies that challenge established paradigms about how the cerebral perfusion pressure and blood flow are related. In the context of blood pressure being a major haemodynamic challenge to the cerebral circulation, we conclude that: (1) the physiological properties of CA remain inconclusive, (2) many extant methods for CA characterisation are based on simplistic assumptions that can give rise to misleading interpretations, and (3) robust evaluation of CA requires thorough consideration not only of active vasomotor function, but also the unique properties of the intracranial environment.

Blood pressure regulation IX: cerebral autoregulation under blood pressure challenges

Cerebral autoregulation (CA) is integral to the delicate process of maintaining stable cerebral perfusion and brain tissue oxygenation against changes in arterial blood pressure. The last four decades has seen dramatic advances in understanding CA physiology, and the role that CA might play in the causation and progression of disease processes that affect the cerebral circulation such as stroke. However, the translation of these basic scientific advances into clinical practice has been limited by the maintenance of old constructs and because there are persistent gaps in our understanding of how this vital vascular mechanism should be quantified. In this review, we re-evaluate relevant studies that challenge established paradigms about how the cerebral perfusion pressure and blood flow are related. In the context of blood pressure being a major haemodynamic challenge to the cerebral circulation, we conclude that: (1) the physiological properties of CA remain inconclusive, (2) many extant methods for CA characterisation are based on simplistic assumptions that can give rise to misleading interpretations, and (3) robust evaluation of CA requires thorough consideration not only of active vasomotor function, but also the unique properties of the intracranial environment.

Hemodynamic effects of L-threo-3,4-dihydroxyphenylserine (Droxidopa) in hypotensive individuals with spinal cord injury

OBJECTIVES

To determine the effect of an escalating dose of droxidopa (100, 200, and 400 mg) compared with placebo on seated blood pressure (BP) in hypotensive individuals with spinal cord injury (SCI). Secondarily, we aimed to determine the effect of droxidopa on (1) supine BP and heart rate, (2) the change in BP and heart rate when these individuals were transferred from the supine to the seated position, and (3) adverse event (AE) reporting.

DESIGN

Open-label dose titration trial.

SETTING

A Veterans Administration Medical Center.

PARTICIPANTS

Participants with SCI (C3-T12) (N=10) were studied during 4 laboratory visits. Subjects visited the laboratory for about 5 hours on each visit, which incorporated a 30-minute seated baseline, a 30- to 60-minute supine, and a 4-hour seated postdrug observation.

INTERVENTIONS

Placebo on visit 1, droxidopa 100 mg on visit 2, droxidopa 200 mg on visit 3, and droxidopa 400 mg on visit 4.

MAIN OUTCOME MEASURES

BP and heart rate changes from baseline to the postdrug period, orthostatic heart rate and BP responses, and subjective AE reporting.

RESULTS

Seated BP was significantly elevated with 400 mg droxidopa compared with placebo and 100 mg droxidopa for 3 hours and was elevated for 2 hours compared with 200 mg droxidopa. Increase in supine BP was not worsened following droxidopa, and the expected fall in BP when transferred to the seated position was prevented with droxidopa 200 and 400 mg. There were no significant differences in the heart rate response or AE reporting among the study visits.

CONCLUSIONS

Our preliminary findings suggest that droxidopa, at the doses tested, does not cause excessive increases in supine BP and the 400-mg dose appears to be effective at increasing seated BP for up to 3 hours in persons with SCI.

Impact of blood pressure dysregulation on health-related quality of life in persons with spinal cord injury: development of a conceptual model

OBJECTIVES

To identify medically relevant aspects of blood pressure dysregulation (BPD) related to quality of life in individuals with spinal cord injury (SCI), and to propose an integrated conceptual framework based on input from both individuals with SCI and their clinical providers. This framework will serve as a guide for the development of a patient-reported outcome (PRO) measure specifically related to BPD.

DESIGN

Three focus groups with individuals with SCI and 3 groups with SCI providers were analyzed using grounded-theory based qualitative analysis to ascertain how blood pressure impacts health-related quality of life (HRQOL) in individuals with SCI.

SETTING

Focus groups were conducted at 2 Veterans Affairs medical centers and a research center.

PARTICIPANTS

Individuals with SCI (n=27) in 3 focus groups and clinical providers (n=25) in 3 focus groups.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Not applicable.

RESULTS

Qualitative analysis indicated that all focus groups spent the highest percentage of time discussing symptoms of BPD (39%), followed by precipitators/causes of BPD (16%), preventative actions (15%), corrective actions (12%), and the impact that BPD has on social or emotional functioning (8%). While patient/consumer focus groups and provider focus groups raised similar issues, providers spent more time discussing precipitators/causes of BPD and preventative actions (38%) than patient/consumer groups (24%).

CONCLUSIONS

These results suggest that BPD uniquely and adversely impacts HRQOL in persons with SCI. While both individuals with SCI and their providers highlighted the relevant symptoms of BPD, the SCI providers offered additional detailed information regarding the precipitators/causes and what can be done to prevent/treat BPD. Further, the results suggest that persons with SCI are aware of how BPD impacts their HRQOL and are able to distinguish between subtle signs and symptoms. These findings exemplify the need for a validated and sensitive clinical measurement tool that can assess the extent to which BPD impacts HRQOL in patients with SCI.

Decentralized cardiovascular autonomic control and cognitive deficits in persons with spinal cord injury

Spinal cord injury (SCI) results in motor and sensory impairments that can be identified with the American Spinal Injury Association (ASIA) Impairment Scale (AIS). Although, SCI may disrupt autonomic neural transmission, less is understood regarding the clinical impact of decentralized autonomic control. Cardiovascular regulation may be altered following SCI and the degree of impairment may or may not relate to the level of AIS injury classification. In general, persons with lesions above T1 present with bradycardia, hypotension, and orthostatic hypotension; functional changes which may interfere with rehabilitation efforts. Although many individuals with SCI above T1 remain overtly asymptomatic to hypotension, we have documented deficits in memory and attention processing speed in hypotensive individuals with SCI compared to a normotensive SCI cohort. Reduced resting cerebral blood flow (CBF) and diminished CBF responses to cognitive testing relate to test performance in hypotensive non-SCI, and preliminary evidence suggests a similar association in individuals with SCI. Persons with paraplegia below T7 generally present with a normal cardiovascular profile; however, our group and others have documented persistently elevated heart rate and increased arterial stiffness. In the non-SCI literature there is evidence supporting a link between increased arterial stiffness and cognitive deficits. Preliminary evidence suggests increased incidence of cognitive impairment in individuals with paraplegia, which we believe may relate to adverse cardiovascular changes. This report reviews relevant literature and discusses findings related to the possible association between decentralized cardiovascular autonomic control and cognitive dysfunction in persons with SCI.

Cardiovascular risk factors promote brain hypoperfusion leading to cognitive decline and dementia

Heart disease is the major leading cause of death and disability in the world. Mainly affecting the elderly population, heart disease and its main outcome, cardiovascular disease, have become an important risk factor in the development of cognitive decline and Alzheimer's disease (AD). This paper examines the evidence linking chronic brain hypoperfusion induced by a variety of cardiovascular deficits in the development of cognitive impairment preceding AD. The evidence indicates a strong association between AD and cardiovascular risk factors, including ApoE(4), atrial fibrillation, thrombotic events, hypertension, hypotension, heart failure, high serum markers of inflammation, coronary artery disease, low cardiac index, and valvular pathology. In elderly people whose cerebral perfusion is already diminished by their advanced age, additional reduction of cerebral blood flow stemming from abnormalities in the heart-brain vascular loop ostensibly increases the probability of developing AD. Evidence also suggests that a neuronal energy crisis brought on by relentless brain hypoperfusion may be responsible for protein synthesis abnormalities that later result in the classic neurodegenerative lesions involving the formation of amyloid-beta plaques and neurofibrillary tangles. Insight into how cardiovascular risk factors can induce progressive cognitive impairment offers an enhanced understanding of the multifactorial pathophysiology characterizing AD and ways at preventing or managing the cardiovascular precursors of this dementia.

Cognitive and MRI correlates of orthostatic hypotension in Parkinson's disease

Orthostatic hypotension (OH) is a frequent nonmotor feature of Parkinson's disease (PD), and its occurrence has been associated with cognitive impairment. The underlying mechanism could be mediated by development of cerebrovascular disease induced by chronic or episodic hypoperfusion, but the extent of brain vascular load in PD patients with OH has never been investigated. This study aimed to assess the relationship between OH and cognitive function in PD patients and to investigate the contribution of brain vascular lesions. Forty-eight PD patients underwent a tilt table test (TT) to assess supine and orthostatic blood pressure as well as an extensive neuropsychological evaluation to evaluate cognitive function. Brain magnetic resonance imaging was acquired in 44/48 patients and analyzed by a visual semiquantitative scale. Twenty-three patients presented OH at TT (13/23 were symptomatic), and 25 did not. There were no differences in motor severity or disease duration between patients with and without OH. In patients with OH we found significantly worse cognitive performance in specific tasks, such as sustained attention, visuospatial and verbal memory, compared with patients without OH. However, there were no differences in vascular burden between the two groups. Our study confirms that there is an association between OH and selective cognitive deficits in PD, but rebuts the hypothesis that this is underlined by the development of cerebrovascular disease.

Hemodynamic and autonomic modifications during sleep stages in young hypotensive women

This study examined cardiovascular activity and autonomic involvement during sleep in essential hypotension. We compared young female hypotensives and normotensives using ambulatory blood pressure monitoring, impedance cardiography, and frequency-domain analysis of heart rate variability during a night of polysomnographic recording. Hypotensives, as compared to normotensives, exhibited lower blood pressure, reduced myocardial contractility and reduced sympathovagal balance across the whole night. Both groups exhibited a reduction in cardiovascular involvement from wake to sleep with similar cardiovascular activity during wake and REM. No group difference was observed in sleep architecture suggesting similar sleeping quality in hypotensives and normotensives. The lower blood pressure and reduced myocardial contractility associated with a lower sympathovagal balance in hypotensives, as compared to normotensives, suggest a night-time hypoactivation of the cardiovascular system supporting the hypothesis of impairment in autonomic control in essential hypotension.

31st g. Heiner sell lectureship: secondary medical consequences of spinal cord injury

Persons with spinal cord injury (SCI) have secondary medical consequences of paralysis and/or the consequences of extreme inactivity. The metabolic changes that result from reduced activity include insulin resistance with carbohydrate disorders and dyslipidemia. A higher prevalence of coronary artery calcification was found in persons with SCI than that in matched able-bodied controls. A depression in anabolic hormones, circulating testosterone and growth hormone, has been described. Adverse soft tissue body composition changes of increased adiposity and reduced skeletal muscle are appreciated. Immobilization is the cause for sublesional disuse osteoporosis with an associated increased risk of fragility fracture. Bowel dysmotility affects all segments of the gastrointestinal tract, with an interest in better defining and addressing gastroesophageal reflux disease and difficulty with evacuation. Developing and testing more effective approaches to cleanse the bowel for elective colonoscopy are being evaluated. The extent of respiratory dysfunction depends on the level and completeness of SCI. Individuals with higher spinal lesions have both restrictive and obstructive airway disease. Pharmacological approaches and expiratory muscle training are being studied as interventions to improve pulmonary function and cough strength with the objective of reducing pulmonary complications. Persons with spinal lesions above the 6th thoracic level lack both cardiac and peripheral vascular mechanisms to maintain blood pressure, and they are frequently hypotensive, with even worse hypotension with upright posture. Persistent and/or orthostatic hypotension may predispose those with SCI to cognitive impairments. The safety and efficacy of anti-hypotensive agents to normalize blood pressure in persons with higher level cord lesions is being investigated.