A comparison of cognitive ability in normotensive and hypertensive 68-year-old men: results from population study "men born in 1914," in Malmö, Sweden

Elevated late-life blood pressure may maintain brain oxygenation and slow amyloid-β accumulation at the expense of cerebral vascular damage

Hypertension in midlife contributes to cognitive decline and is a modifiable risk factor for dementia. The relationship between late-life hypertension and dementia is less clear. We have investigated the relationship of blood pressure and hypertensive status during late life (after 65 years) to post-mortem markers of Alzheimer's disease (amyloid-β and tau loads); arteriolosclerosis and cerebral amyloid angiopathy; and to biochemical measures of ante-mortem cerebral oxygenation (the myelin-associated glycoprotein:proteolipid protein-1 ratio, which is reduced in chronically hypoperfused brain tissue, and the level of vascular endothelial growth factor-A, which is upregulated by tissue hypoxia); blood-brain barrier damage (indicated by an increase in parenchymal fibrinogen); and pericyte content (platelet-derived growth factor receptor β, which declines with pericyte loss), in Alzheimer's disease (n = 75), vascular (n = 20) and mixed dementia (n = 31) cohorts. Systolic and diastolic blood pressure measurements were obtained retrospectively from clinical records. Non-amyloid small vessel disease and cerebral amyloid angiopathy were scored semiquantitatively. Amyloid-β and tau loads were assessed by field fraction measurement in immunolabelled sections of frontal and parietal lobes. Homogenates of frozen tissue from the contralateral frontal and parietal lobes (cortex and white matter) were used to measure markers of vascular function by enzyme-linked immunosorbent assay. Diastolic (but not systolic) blood pressure was associated with the preservation of cerebral oxygenation, correlating positively with the ratio of myelin-associated glycoprotein to proteolipid protein-1 and negatively with vascular endothelial growth factor-A in both the frontal and parietal cortices. Diastolic blood pressure correlated negatively with parenchymal amyloid-β in the parietal cortex. In dementia cases, elevated late-life diastolic blood pressure was associated with more severe arteriolosclerosis and cerebral amyloid angiopathy, and diastolic blood pressure correlated positively with parenchymal fibrinogen, indicating blood-brain barrier breakdown in both regions of the cortex. Systolic blood pressure was related to lower platelet-derived growth factor receptor β in controls in the frontal cortex and in dementia cases in the superficial white matter. We found no association between blood pressure and tau. Our findings demonstrate a complex relationship between late-life blood pressure, disease pathology and vascular function in dementia. We suggest that hypertension helps to reduce cerebral ischaemia (and may slow amyloid-β accumulation) in the face of increasing cerebral vascular resistance, but exacerbates vascular pathology.

Hypertension and cognition are minimally associated in late life

Hypertension impacts approximately 65% of persons over 60 years of age. Although previous studies have proposed an association between mid-life hypertension and late-life cognition, reports of associations between late-life hypertension and cognition have been mixed in the direction and magnitude of the observed associations and in the cognitive domains that may be affected. This study contrasted older adults with and without self-reported hypertension at two time points in late life (M_{Baseline age} = 64.3 years, SD₁ = 0.7; M_{Follow-up age} = 71.2 years, SD₂ = 0.9), separated by approximately seven years. Participants included 4314 1957 high school graduates from the Wisconsin Longitudinal Study who were followed longitudinally until 2011. Cognitive, demographic, and health variables from the 2003-2005 and 2011 data collection waves were used. Cognitive measures included letter and category fluency, digit ordering, similarities, and immediate and delayed recall. Bayesian independent t tests and regressions examined the association between self-reported hypertension status and cognition at baseline and follow-up. Persons with self-reported hypertension over seven years showed slightly worse letter fluency and digit ordering performance at follow-up than persons without self-reported hypertension. No baseline cognitive differences were observed between groups. Participants with self-reported hypertension showed no improvement in letter fluency or digit ordering compared to persons without self-reported hypertension. After controlling for cardiovascular risk factors, hypertension was associated only with a slight decline in letter fluency. Finally, hypertension duration was not associated with cognitive performance. Self-reported hypertension was associated with minimal to no effects on cognition in older adults. Controlling for cardiovascular risk factors eliminated virtually all associations between self-reported hypertension and cognition.

Effects of Blood Pressure on Cognitive Performance in Aging: A Systematic Review

Introduction: Cognitive functions play a crucial role in daily functioning. Unfortunately, some cognitive abilities decline in the process of healthy aging. An increasing body of evidence has highlighted the role of lifestyle habits and cardiovascular diseases, such as high blood pressure, in increasing the risk of cognitive decline. Surprisingly, although hypertension is a modifiable risk factor for cerebrovascular damage, the role of hypertension on cognitive impairment development is not still clear. Several key questions remain unresolved, and there are many inconsistent results in studies considering this topic. This review is aimed to systematically analyze the results found by the studies that investigated whether high blood pressure, in both hypertensive and healthy people, is related to cognitive performance. Furthermore, it points to evaluate the role of age in this relationship. Method: The review process was conducted according to the PRISMA statement. Restrictions were made, selecting the studies in English and published in peer-review journals, including at least one cognitive measure and blood pressure measurement. Studies that included participants with medical conditions, dementia, psychiatric disorders, strokes, and brain injury were excluded. Cross-sectional and longitudinal studies were analyzed separately. Finally, blood pressure measured at young life (18–39 years), midlife (age 40–64 years), elderly (65–74 years), and old age (≥75 years) were considered. Results: The review allows 68 studies to be selected, which include 154,935 participants. The results provided evidence of an adverse effect of exposure to high blood pressure on cognitive performance. High blood pressure in midlife was linked with poorer cognitive functioning; this evidence was found in cross-sectional and longitudinal studies. However, this association declines with increasing age and tends to become inconsistent. In older people, the relationship between blood pressure and cognitive performance is non-linear, highlighting a beneficial effect of high blood pressure on cognition. Conclusions: Despite some limitations, this review showed that cardiovascular and neuro-cognitive systems do not operate in isolation, but they are related. Blood pressure can be considered an early biomarker of cognitive impairment, and the necessity of early blood pressure measurement and control was underlined.

Hypertension and the Risk of Dementia

Hypertension, particularly midlife high blood pressure, has been related to a higher risk of cognitive decline and dementia, including Alzheimer disease. However, these associations are complex and not fully elucidated. Cerebral small vessel disease emerges as one of the most important causes. Several observational studies have shown the potential beneficial role of antihypertensive treatment in preventing cognitive decline. However, randomized clinical trials (RCTs) have shown controversial results without proving nor disproving the association. On the other hand, in very elderly or frail people some studies have observed a relationship between low blood pressure and worse cognitive function. The optimal systolic and diastolic blood pressure values for protecting cognitive function, especially in elderly people, are not known.

Effects of Blood Pressure on Cognitive Performance: A Systematic Review

Background: High blood pressure has been associated with an increased risk of developing cognitive impairment. However, this relationship is unclear. This study aims to systematically review the effects of blood pressure on executive functioning, language, memory, attention and processing speed. Methods: The review process was conducted according to the PRISMA-Statement, using the PubMed, PsycINFO, PsycARTICLES and MEDLINE databases. Restrictions were made by selecting studies, which included one or more cognitive measures and reported blood pressure recordings. Studies that included participants with medical conditions or people diagnosed with dementia, psychiatric disorders, stroke and head trauma were excluded. The review allows selecting fifty studies that included 107,405 participants. The results were reported considering different cognitive domains separately: global cognitive functioning, attention, processing speed, executive functions, memory and visuospatial abilities. Results: Higher blood pressure appears to influence cognitive performance in different domains in the absence of dementia and severe cardiovascular diseases, such as strokes. This relationship seems to be independent of demographic factors (gender and education), medical co-morbidity (diabetes), and psychiatric disorders (depression). Furthermore, it presents different patterns considering ageing. In the elderly, a sort of “cardiovascular paradox” is highlighted, which allows considering higher blood pressure as a protective factor for cognitive functioning. Conclusions: The results underline that higher blood pressure is associated with a higher risk of cognitive decline in people without dementia or stroke. These findings highlight the need to introduce early management of blood pressure, even in the absence of clinical hypertension, to prevent the risk of a decline of cognitive functioning typically associated with ageing.

Comparison of processing speed, balance, mobility and fear of falling between hypertensive and normotensive individuals

BACKGROUND

Hypertension (HT) contributes substantially to poor physical function, cognitive dysfunction, cardiovascular problems and to all-cause mortality. Performance in activities requiring attention, speed and coordination might also be affected in individuals with HT.

OBJECTIVE

This study compared the processing speed, static and dynamic balance, functional mobility and fear of falling between individuals with hypertension (HT group) and normotensive individuals (NT group).

METHODS

One-hundred and twenty-eight individuals were included: NT group (n = 64) and HT group (n = 64). The Choice Stepping Reaction Time Test was used for the evaluation of processing speed, Single Leg Stance test for static balance evaluation, "Y" Balance Test for dynamic balance evaluation, Timed Up and Go test with single and dual tasking for the evaluation of functional mobility and Falls Efficacy Scale for assessing fear of falling.

RESULTS

The processing speed of the HT group was slower than that of the NT group; the total response time (RsT) in Stepping Reaction Test (SRT) (mean difference [MD] = -0.2, 95% CI = -0.3, 0), and Stroop Test (ST) [ST-A (MD = -0.4, 95% CI = -0.5, -0.2), ST-B (MD = -0.5, 95% CI = -0.7, -0.2) and ST-C (MD = -0.6, 95% CI = -0.8, -0.3). Additionally, the static [single leg stance, eyes open, right side (MD = 12.7, 95% CI = 6.3, 19.0) and left side (MD = 13.6, 95% CI = 7.2, 19.9)] and dynamic balance [Y balance test, composite score, right lower extremity (MD = 8.5, 95% CI = 4.4, 12.5) and left lower extremity (MD = 5.2, 95% CI = 1.5, 8.8) scores of the HT group were lower than those of the NT group. The HT group required a longer time to complete the functional mobility test measured with Timed Up And Go Test during both single task (MD = -0.8, 95% CI = -1.1, -0.4), cognitive dual task (MD = -1.5, 95% CI = -2.4, -0.5) and manual dual task (MD = -0.9, 95% CI = -1.3, -0.4) in comparison to the NT group. Also, the HT group had higher levels of fear of falling (MD = -7.6, 95% CI = -10.9, -4.2).

CONCLUSION

Hypertensive individuals present slower processing speed, reduced static and dynamic balance, decreased functional mobility and higher fear of falling in comparison to normotensive individuals.

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.

Interactive effects of subjective memory complaints and hypertension on learning and memory performance in the elderly

This study evaluated whether the relation between subjective memory complaints and cognitive performance is influenced by the presence of hypertension in the elderly. One hundred and five healthy older adults, 70-89 years of age, with and without hypertension treatment or diagnosis, completed a scale of subjective memory complaints. Participants were divided into those with mild memory concerns and those with minimal or no complaints. All participants completed a battery of neuropsychological tests including measures of verbal and nonverbal memory. After controlling for differences in age, gender, education, and overall intellectual ability, there were significant main effects for memory concerns and significant interactions for memory complaints and hypertension on several measures of memory performance. There were no main effects for hypertension on memory performance. Simple effects analyses of the interactions showed that the hypertensive complainers demonstrated poorer performance on measures of long-term memory and greater reliance on short-term recall than the hypertensive non-complainers. There were no differences in memory performance for the non-hypertensive groups. Among healthy elderly community-dwelling adults, those with mild subjective memory complaints in the context of hypertension demonstrated greater objective cognitive difficulties than those without hypertension as well as a greater reliance on a less efficient learning strategy. These findings suggest that memory concerns in the presence of hypertension may be important when evaluating treatment efficacy in these individuals and for identifying differences in cognitive aging.

Cognitive impairment and cardiovascular diseases in the elderly. A heart-brain continuum hypothesis

The aging population is increasing and, therefore, a higher prevalence of cardiac disease is emerging; including hypertension, coronary artery disease, atrial fibrillation and chronic heart failure. Large cohort studies have revealed a relationship among increased risk for cognitive impairment and dementia in cardiovascular diseases probably due to embolic stroke or chronic cerebral hypoperfusion. Thus, the aim of the present review is to overview the studies that investigate the presence and/or the development of cognitive impairments and dementia in patients with varied types of cardiovascular disease. Finally, a continuum among hypertension, coronary artery disease, atrial fibrillation and chronic heart failure with to the development of cognitive impairment and progression to dementia has been hypothesized.

Exploring the within-person coupling of blood pressure and cognition in elders

In this study, we examined the relationship between within-person blood pressure and cognitive functioning. We conducted an analysis on 36 community-dwelling elderly individuals (age range = 60-87 years). Participants measured their blood pressure and completed cognitive tasks (i.e., the Rey Auditory Verbal Learning Task, the Letter Series test, and the Number Comparison test) twice a day over 60 consecutive days. We observed a significant interaction between within-person change in blood pressure and average blood pressure for the Letter Series test. Individuals with high blood pressure tended to perform poorly, particularly on occasions when their blood pressure level was above their personal average. These results demonstrate that the relationship between blood pressure and cognition at the between-person level and the relationship within each individual should be further explored simultaneously.

Preventing Alzheimer's disease : separating fact from fiction

Alzheimer's disease is an ever-increasing health concern among the aging population, and as we research new and existing treatments for this disease we begin to uncover possibilities for its prevention. Observational studies and animal models have provided promising findings and generated excitement, but placebo-controlled clinical trials are required to demonstrate true efficacy for these treatments.In the past two decades, clinical trials have led to the approval of symptomatic treatments for Alzheimer's disease, including cholinesterase inhibitors and, more recently, an NMDA receptor antagonist. Clinical trials have also examined antioxidants, NSAIDs, hormone replacement, nutritional supplements and nonpharmacological interventions for the treatment and prevention of Alzheimer's disease. While the results of many of these trials have been disappointing, new mechanisms targeting the hallmark pathology of Alzheimer's disease are currently under investigation, including immunotherapy and secretase modulation, targeted at reducing the amyloid burden, for which we await the results. We review the evidence from completed trials, support for ongoing studies and propose directions for future research.

Type 2 diabetes mellitus, hypertension, dyslipidemia and obesity: A systematic comparison of their impact on cognition

Vascular risk factors, such as type 2 diabetes mellitus, hypertension, dyslipidemia and obesity, have been associated with an increased risk of cognitive dysfunction, particularly in the elderly. The aim of this systematic review was to compare these risk factors with regard to the nature and magnitude of the associated cognitive decrements. Cross-sectional and longitudinal studies that assessed cognitive functioning in non-demented persons in relation to diabetes/impaired glucose metabolism (k = 36), hypertension (k = 24), dyslipidemia (k = 7) and obesity (k = 6) and that adjusted or matched for age, gender and education were included. When possible, effect sizes (Cohen's d) were computed per cognitive domain. Diabetes and hypertension were clearly associated with cognitive decrements; the results for obesity and dyslipidemia were less consistent. Effect sizes were moderate (median approximately -0.3) for all risk factors. Decline was found in all cognitive domains, although the effects on cognitive speed, mental flexibility and memory were most consistent. Methodological aspects of included studies and implications of these findings are discussed.

Relation of Blood Pressure to Cognitive Impairment and Dementia

Over the past decade several studies have assessed the relation of blood pressure with cognitive function and dementia. While some cross-sectional studies have shown an inverse association between blood pressure levels and cognitive performance or dementia, longitudinal studies yielded controversial results. Most studies relating blood pressure levels in mid-life with late-life risk of cognitive decline or dementia reported a harmful effect of higher blood pressure levels on cognitive function. Studies assessing the effect of late-life blood pressure levels reported that low diastolic and very high systolic levels may increase the risk. Observational studies and randomized cinical trials provide limited evidence for a protective effect of antihypertensive therapy. It seems that the older the person and the more advanced the disease process, the less harmful or even inverted the effect of blood pressure elevation on dementia risk. The reason for this may be that blood pressure declines with age-related pathology, such as vessel stiffening, weight loss, and changes in the autonomic regulation of blood flow.

Cardiac risk factors and potential treatments in Alzheimer's disease

Dementia is one of the commonest neurological disorders in the elderly population. In regards to the increasing longevity of populations worldwide, prevention of dementia has become a major public health challenge. There has been an intense research in the identification of modifiable risk factors for dementia. These risk factors could then be used as targets for intervention, pharmacologic or non-pharmacologic. Numerous reports of the relation between cardiovascular risk factors and cognitive decline and dementia have been published over the past years. This review focuses on the cardiovascular risk factors hypertension, hyperlipidemia and diabetes mellitus as targets for prevention of cognitive decline, overall dementia and Alzheimer's disease. Observational studies and clinical trials regarding the association between antihypertensive, lipid lowering and antidiabetic medications and the risk of impaired cognition, dementia or Alzheimer's disease are reviewed. Based on these data, we propose that early interventions at reducing these cardiovascular risk factors may have an impact on future incidence and prevalence of cognitive deficits of many etiologies including Alzheimer's disease.

Lower blood pressure correlates with poorer performance on visuospatial attention tasks in younger individuals

The relationship between low blood pressure and cognitive function among younger individuals is not fully understood. While a number of studies have examined hypertensive and hypotensive individuals, particularly in older populations, little attention has been devoted to healthy, young populations. We tested 105 healthy young individuals whose blood pressure levels naturally fell in the below normal-to-normal range. Our primary finding was a positive relation between blood pressure and cognition, as measured by two visuospatial attention tasks. This relation appears to be specific to visuospatial skills, as no relationship was observed between recognition memory and blood pressure. We discuss possible explanations for this positive relationship, such as structural neural mechanisms, and how they apply to the overall blood pressure-cognition relationship.

The age-dependent relation of blood pressure to cognitive function and dementia

The relation of blood pressure with cognitive function and dementia has, in recent years, received much attention from epidemiological research. Some cross-sectional studies have shown an inverse association between blood pressure and the prevalence of dementia and Alzheimer's disease, whereas longitudinal studies yield mixed results that largely depend on the age at which blood pressure is measured and the time interval between blood pressure and outcome assessments. Some studies suggest that midlife high blood pressure is a risk factor for late-life cognitive impairment and dementia, and that low diastolic pressure and very high systolic pressure in older adults may be associated with subsequent development of dementia and Alzheimer's disease. Observational studies and randomised clinical trials provide limited evidence for a protective effect of antihypertensive therapy against dementia and stroke-related cognitive decline. Atherosclerosis resulting from long-standing hypertension, and cerebral hypoperfusion secondary to severe atherosclerosis and to low blood pressure may be major biological pathways linking both high blood pressure in midlife and low blood pressure in late-life to cognitive decline and dementia.

Is blood pressure at 68 an independent predictor of cognitive decline at 81? Results from follow-up study "Men born in 1914", Malmö, Sweden

One hundred and sixty-eight men who were participants in the study "Men born in 1914" had their blood pressure and cognitive function examined when they were 68 years old. They were then re-examined at the age of 81. Decline on five standardized cognitive tests at the age of 81 years was studied in relation to four levels of baseline blood pressure at the age of 68. Results from multivariate analyses suggested that blood pressure, when studied in conjunction with other factors related to cognitive function, contribute to a rather modest extent and not unambiguously to the variability in cognitive decline. When decline on each separate test had been combined into a composite measure, where equal weight had been given to memory, crystallized and fluid abilities, it was shown that hypertension stage 2 (SBP 160-179 mmHg or DBP 100-109 mmHg) was associated with greater levels of overall decline. Hypertension stage 3 (SBP > or =180 mmHg or DBP > or =110 mmHg), on the other hand, was associated with lower levels of overall decline. Depressive symptoms at follow-up had a negative effect on cognitive levels and were discussed as potential confounders of hypertension-related cerebral lesions.