Autoregulation of blood pressure and thought: preliminary results of an application of brain imaging to psychosomatic medicine

White Matter Characteristics of Damage Along Fiber Tracts in Patients with Type 2 Diabetes Mellitus

Purpose

The white matter (WM) of the brain of type 2 diabetes mellitus (T2DM) patients is susceptible to neurodegenerative processes, but the specific types and positions of microstructural lesions along the fiber tracts remain unclear.

Methods

In this study 61 T2DM patients and 61 healthy controls were recruited and underwent diffusion spectrum imaging (DSI). The results were reconstructed with diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI). WM microstructural abnormalities were identified using tract-based spatial statistics (TBSS). Pointwise WM tract differences were detected through automatic fiber quantification (AFQ). The relationships between WM tract abnormalities and clinical characteristics were explored with partial correlation analysis.

Results

TBSS revealed widespread WM lesions in T2DM patients with decreased fractional anisotropy and axial diffusivity and an increased orientation dispersion index (ODI). The AFQ results showed microstructural abnormalities in T2DM patients in specific portions of the right superior longitudinal fasciculus (SLF), right arcuate fasciculus (ARC), left anterior thalamic radiation (ATR), and forceps major (FMA). In the right ARC of T2DM patients, an aberrant ODI was positively correlated with fasting insulin and insulin resistance, and an abnormal intracellular volume fraction was negatively correlated with fasting blood glucose. Additionally, negative associations were found between blood pressure and microstructural abnormalities in the right ARC, left ATR, and FMA in T2DM patients.

Conclusion

Using AFQ, together with DTI and NODDI, various kinds of microstructural alterations in the right SLF, right ARC, left ATR, and FMA can be accurately identified and may be associated with insulin and glucose status and blood pressure in T2DM patients.

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

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

The Dose-Dependent Effects of Vascular Risk Factors on Dynamic Compensatory Neural Processes in Mild Cognitive Impairment

Background/Objectives: Mild cognitive impairment (MCI) has been associated with risk for Alzheimer's Disease (AD). Previous investigations have suggested that vascular risk factors (VRFs) were associated with cognitive decline and AD pathogenesis, and the intervention of VRFs may be a possible way to prevent dementia. However, in MCI, little is known about the potential impacts of VRFs on neural networks and their neural substrates, which may be a neuroimaging biomarker of the disease progression.

Methods: 128 elderly Han Chinese participants (67 MCI subjects and 61 matched normal elderly) with or without VRFs (hypertension, diabetes mellitus, hypercholesterolemia, smoking and alcohol drinking) underwent the resting-state functional magnetic resonance imaging (fMRI) and neuropsychological tests. We obtained the default mode network (DMN) to identify alterations in MCI with the varying number of the VRF and analyzed the significant correlation with behavioral performance.

Results: The effects of VRF on the DMN were primarily in bilateral dorsolateral prefrontal cortex (DLPFC) (i.e., middle frontal gyrus). Normal elderly showed the gradually increased functional activity of DLPFC, while a fluctuant activation of DLPFC was displayed in MCI with the growing number of the VRF. Interestingly, the left DLPFC further displayed significantly dynamic correlation with executive function as the variation of VRF loading. Initial level of compensation was observed in normal aging and none-vascular risk factor (NVRF) MCI, while these compensatory neural processes were suppressed in One-VRF MCI and were subsequently re-aroused in Over-One-VRF MCI.

Conclusions: These findings suggested that the dose-dependent effects of VRF on DLPFC were highlighted in MCI, and the dynamic compensatory neural processes that fluctuated along with variations of VRF loading could be key role in the progression of MCI.

Risk Factors for Neurocognitive Functioning in Children with Autosomal Recessive Polycystic Kidney Disease

This mini review provides an overview of the issues and challenges inherent in autosomal recessive polycystic kidney disease (ARPKD), with a particular focus on the neurological factors and neurocognitive functioning of this population. ARPKD typically is discovered at the end of pregnancy or during the neonatal developmental period and occurs in approximately 1 in 20,000 live births. During the neonatal period, there is a relatively high risk of death, with many infants dying from respiratory failure. As the child ages, they experience progressive kidney disease and become increasingly vulnerable to liver disease, with many individuals eventually requiring dual organ transplants. This mini review provides a brief description of ARPKD and describes the various factors that place children with ARPKD at risk for neurological and neuropsychological impairment (e.g., a genetic condition leading to chronic kidney disease and eventual transplant; difficult-to-treat hypertension; eventual liver disease; possible dual transplantation of the kidneys and liver; chronic lung disease), including that these factors are present during a critical period of brain development. Further, the mini review discusses the available studies that have addressed the neurocognitive functioning in children with ARPKD. This paper concludes by providing the key clinical and research challenges that face the field of pediatric nephrology with respect to the clinical and scientific study of the neurocognitive functioning of children with ARPKD. Selected directions are offered in both the clinical and research arenas for this multiorgan chronic condition.

Hyperthymic affective temperament and hypertension are independent determinants of serum brain-derived neurotrophic factor level

BACKGROUND

Brain-derived neurotrophic factor (BDNF) has neuroprotective, proangiogenic and myogenic effects and, therefore, possibly acts as a psychosomatic mediator. Here, we measured serum BDNF (seBDNF) level in hypertensive patients (HT) and healthy controls (CONT) and its relation to affective temperaments, depression and anxiety scales, and arterial stiffness parameters.

METHODS

In this cross-sectional study, affective temperaments, anxiety, and depression were studied with questionnaires (TEMPS-A, HAM-A, and BDI, respectively). SeBDNF level and routine laboratory parameters were measured as well. Arterial stiffness was evaluated with a tonometric method.

RESULTS

Allover, 151 HT, and 32 CONT subjects were involved in the study. SeBDNF level was significantly higher in HT compared to CONT (24880 ± 8279 vs 21202.6 ± 6045.5 pg/mL, p < 0.05). In the final model of regression analysis, hyperthymic temperament score (Beta = 405.8, p = 0.004) and the presence of hypertension (Beta = 6121.2, p = 0.001) were independent determinants of seBDNF. In interaction analysis, it was found that in HT, a unit increase in hyperthymic score was associated with a 533.3 (95 %CI 241.3-825.3) pg/mL higher seBDNF. This interaction was missing in CONT.

CONCLUSIONS

Our results suggest a complex psychosomatic involvement of BDNF in the pathophysiology of hypertension, where hyperthymic affective temperament may have a protective role. BDNF is not likely to have an effect on large arteries.

Neurocognitive Dysfunction in Children, Adolescents, and Young Adults With CKD

BACKGROUND

Neurocognitive dysfunction is a known complication in children with chronic kidney disease (CKD). However, less is known about putative mechanisms or modifiable risk factors. The objective of this study was to characterize and determine risk factors for cognitive dysfunction in children, adolescents, and young adults with CKD compared with controls.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

The Neurocognitive Assessment and Magnetic Resonance Imaging Analysis of Children and Young Adults With Chronic Kidney Disease (NiCK) Study included 90 individuals aged 8 to 25 years with CKD compared with 70 controls.

PREDICTORS

CKD versus control, estimated glomerular filtration rate (eGFR), ambulatory blood pressure.

OUTCOMES

Performance on neurocognitive assessment with relevant tests grouped into 11 domains defined a priori by expert opinion. Results of tests were converted to age-normalized z scores.

MEASUREMENTS

Each neurocognitive domain was analyzed through linear regression, adjusting for eGFR and demographic and clinical variables. For domains defined by multiple tests, the median z score of tests in that domain was used.

RESULTS

We found significantly poorer performance in multiple areas of neurocognitive function among individuals with CKD compared with controls. Particular deficits were seen in domains related to attention, memory, and inhibitory control. Adjusted for demographic and clinical factors, we found lower performance in multiple domains with decreasing eGFRs (attention: β=0.053, P=0.02; visual spatial: β=0.062, P=0.02; and visual working memory: β=0.069, P=0.04). Increased diastolic load and decreased diastolic nocturnal dipping on ambulatory blood pressure monitoring were independently associated with impairments in neurocognitive performance.

LIMITATIONS

Unable to assess changes in neurocognitive function over time, and neurocognitive tests were grouped into predetermined neurocognitive domains.

CONCLUSIONS

Lower eGFR in children, adolescents, and young adults is associated with poorer neurocognitive performance, particularly in areas of attention, memory, and inhibitory control. Hypertension identified on ambulatory blood pressure monitoring may be an important risk factor, illustrating that neurocognitive function is an area of target-organ damage in CKD.

Design and methods of the NiCK study: neurocognitive assessment and magnetic resonance imaging analysis of children and young adults with chronic kidney disease

Background

Chronic kidney disease is strongly linked to neurocognitive deficits in adults and children, but the pathophysiologic processes leading to these deficits remain poorly understood. The NiCK study (Neurocognitive Assessment and Magnetic Resonance Imaging Analysis of Children and Young Adults with Chronic Kidney Disease) seeks to address critical gaps in our understanding of the biological basis for neurologic abnormalities in chronic kidney disease. In this report, we describe the objectives, design, and methods of the NiCK study.

Design/methods

The NiCK Study is a cross-sectional cohort study in which neurocognitive and neuroimaging phenotyping is performed in children and young adults, aged 8 to 25 years, with chronic kidney disease compared to healthy controls. Assessments include (1) comprehensive neurocognitive testing (using traditional and computerized methods); (2) detailed clinical phenotyping; and (3) multimodal magnetic resonance imaging (MRI) to assess brain structure (using T1-weighted MRI, T2-weighted MRI, and diffusion tensor imaging), functional connectivity (using functional MRI), and blood flow (using arterial spin labeled MRI). Primary analyses will examine group differences in neurocognitive testing and neuroimaging between subjects with chronic kidney disease and healthy controls. Mechanisms responsible for neurocognitive dysfunction resulting from kidney disease will be explored by examining associations between neurocognitive testing and regional changes in brain structure, functional connectivity, or blood flow. In addition, the neurologic impact of kidney disease comorbidities such as anemia and hypertension will be explored. We highlight aspects of our analytical approach that illustrate the challenges and opportunities posed by data of this scope.

Discussion

The NiCK study provides a unique opportunity to address key questions about the biological basis of neurocognitive deficits in chronic kidney disease. Understanding these mechanisms could have great public health impact by guiding screening strategies, delivery of health information, and targeted treatment strategies for chronic kidney disease and its related comorbidities.

Blood pressure and cognition among older adults: a meta-analysis

Hypertension has adverse effects on cognition, can alter cerebral vasculature integrity, and is associated with the pathogenesis of dementia. Using meta-analysis, we correlated blood pressure to multiple cognitive domains among older adults free of clinical stroke and dementia. We identified 230 studies indexed in PubMed and PsycINFO relating blood pressure and cognition. After applying exclusion criteria, we selected n = 12 articles with n = 4,076 participants (age range 43-91 years). Meta-analysis yielded an association between blood pressure and episodic memory (r = -.18, p < .001) and between blood pressure and global cognition (r = -.07, p < .001). When limiting analyses to studies adjusting for vascular covariates (n = 8, n = 2,141), blood pressure was modestly related to global cognition (r = -.11, p < .001), attention (r = .14, p = .002), and episodic memory (r = -.20, p < .001) with a trend for language (r = -.22, p = .07). Findings underscore the need to manage blood pressure as a key prevention method in minimizing abnormal cognitive aging prior to the onset of clinical dementia.

Primary hypertension and neurocognitive and executive functioning in school-age children

Data on neurocognitive function in hypertensive children are limited. In this review, we summarize recent preliminary, early studies that suggest that children with elevated blood pressure demonstrate evidence of worse performance on direct neurocognitive testing, as well as evidence of executive dysfunction based on parent ratings, compared with matched normotensive comparison groups. Furthermore, hypertensive children may have increased prevalence of learning disabilities as well as a blunted cerebrovascular reactivity compared with normotensive controls. Larger, prospective studies are needed to confirm and further explore these emerging but preliminary findings.

Neurocognitive alterations in hypertensive children and adolescents

Hypertensive adults demonstrate performance deficits on neuropsychological testing compared with scores of normotensive controls. This article reviews emerging preliminary evidence that children with hypertension also manifest neurocognitive differences when compared with normotensive controls. Database and single-center studies suggest that children with hypertension manifest deficits on measures of neurocognition and have an increased prevalence of learning difficulties and that children with hypertension associated with obesity may be at increased risk for depression and anxiety. Studies suggesting blunted cerebrovascular reactivity in children with hypertension are also reviewed.

The effects of hypertension on cognitive function in children and adolescents

Hypertension (HTN) is found in about 3-4% of the pediatric population with long-term risks of end organ damage if untreated or poorly controlled. Although children with HTN are being more frequently screened for end organ damage (i.e., LVH), the cognitive effects of HTN and methods to screen for cognitive dysfunction have not been extensively explored. In recent years, there have been a small number of studies that have provided important insights that can guide future research in this area. These studies show that HTN can be associated with headaches, restlessness, sleep disturbance, anxiety, depression, decreased attention, and also poor executive functioning. By increasing the utilization of cognitive tests in hypertensive children and adolescents, important cognitive defects secondary to HTN may be detected. More research is needed in the area, and the results of future studies could have far reaching implications for long-term outcomes in hypertensive children and adolescents.

From Brain to Behavior: Hypertension's Modulation of Cognition and Affect

Accumulating evidence from animal models and human studies of essential hypertension suggest that brain regulation of the vasculature is impacted by the disease. Human neuroimaging findings suggest that the brain may be an early target of the disease. This observation reinforces earlier research suggesting that psychological factors may be one of the many contributory factors to the initiation of the disease. Alternatively or in addition, initial blood pressure increases may impact cognitive and/or affective function. Evidence for an impact of blood pressure on the perception and experience of affect is reviewed vis-a-vis brain imaging findings suggesting that such involvement in hypertensive individuals is likely.

Interactions between systemic hemodynamics and cerebral blood flow during attentional processing

The study explored interactions between systemic hemodynamics and cerebral blood flow during attentional processing. Using transcranial Doppler sonography, blood flow velocities in the middle cerebral arteries (MCA) of both hemispheres were recorded while 50 subjects performed a cued reaction time task. Finger arterial pressure and heart rate were also continuously monitored. Doppler sonography revealed a right dominant blood flow response. The extent of the increase measured in second two of the interstimulus interval showed a clear positive association with reaction speed. Task-related changes in blood pressure and heart rate proved predictive of changes in MCA flow velocities in limited time windows of the response. Besides an association between cerebral blood flow and attentional performance, the results suggest a marked impact of systemic hemodynamics on the blood flow response. All observed interactions are highly dynamic in time.

Parental assessment of executive function and internalizing and externalizing behavior in primary hypertension after anti-hypertensive therapy

OBJECTIVE

To determine the change in parental ratings of executive function and behavior in children with primary hypertension after anti-hypertensive therapy.

STUDY DESIGN

Parents of subjects with untreated hypertension and control subjects completed the Behavior Rating Inventory of Executive Function (BRIEF) to assess behavioral correlates of executive function and the Child Behavior Checklist (CBCL) to assess internalizing and externalizing behaviors. Subjects with hypertension subsequently received anti-hypertensive therapy to achieve casual blood pressure (BP)<95th percentile. After 12 months, all parents again completed the BRIEF and CBCL.

RESULTS

Twenty-two subjects with hypertension and 25 normotensive control subjects underwent both baseline and 12-month assessments. The BP of subjects with hypertension improved (24-hour systolic BP [SBP] load: mean baseline versus 12-months, 60% versus 25%, P<.001). Parent ratings of executive function improved from baseline to 12 months in the subjects with hypertension (BRIEF Global Executive Composite T-score, Delta=-5.9, P=0.001), but not in the normotensive control subjects (Delta=-0.36, P=.83). In contrast, T-scores on the CBCL Internalizing and Externalizing summary scales did not change significantly from baseline to 12 months in either subjects with hypertension or control subjects.

CONCLUSIONS

Children with hypertension demonstrated improvement in parental ratings of executive function after 12 months of anti-hypertensive therapy.

Cognitive performance in hypotensive persons with spinal cord injury

BACKGROUND

Due to sympathetic de-centralization, individuals with spinal cord injury (SCI), especially those with tetraplegia, often present with hypotension, worsened with upright posture. Several investigations in the non-SCI population have noted a relationship between chronic hypotension and deficits in memory, attention and processing speed and delayed reaction times.

OBJECTIVE

To determine cognitive function in persons with SCI who were normotensive or hypotensive over a 24-h observation period while maintaining their routine activities.

METHODS

Subjects included 20 individuals with chronic SCI (2-39 years), 13 with tetraplegia (C4-8) and 7 with paraplegia (T2-11). Individuals with hypotension were defined as having a mean 24-h systolic blood pressure (SBP) below 110 mmHg for males and 100 mmHg for females, and having spent >or=50% of the total time below these gender-specific thresholds. The cognitive battery used included assessment of memory (CVLT), attention and processing speed (Digit Span, Stroop word and color and Oral Trails A), language (COWAT) and executive function (Oral Trails B and Stroop color-word).

RESULTS

Demographic parameters did not differ among the hypotensive and normotensive groups; the proportion of individuals with tetraplegia (82%) was higher in the hypotensive group. Memory was significantly impaired (P < 0.05) and there was a trend toward slowed attention and processing speed (P < 0.06) in the hypotensive compared to the normotensive group.

INTERPRETATION

These preliminary data suggest that chronic hypotension in persons with SCI is associated with deficits in memory and possibly attention and processing speed, as previously reported in the non-SCI population.

Is the brain the essential in hypertension?

The brain is typically considered a target for late stage hypertensive disease due to the high prevalence of stroke among hypertensive patients. Research is reviewed, however, that suggests that the brain is implicated in the initiation of high blood pressure and is itself altered by early disease processes. A substantial literature establishes neural control of the vasculature and kidney as candidate etiological factors in essential hypertension. This research, largely done in animals, is now supplemented by behavioral and brain imaging studies in humans. This review suggests that the brain and vasculature may be independently and concurrently targeted by the factors inducing essential hypertension. Early stage hypertension is associated with cognitive deficits, altered cerebral blood flow support for cognitive processing, and decreased grey matter in specific cortical regions. Pharmacological reversal of hypertension is less successful in patients with premature brain aging and fails to reverse either the progression of functional or structural changes within the cerebral cortex. Furthermore, magnetic resonance imaging Blood Oxygen Level-Dependent (BOLD) responses during psychological challenge differ between normotensive individuals at risk and those not at risk for hypertension because of their exaggerated blood pressure responses to psychological challenge. Further examination of mechanisms of action and early influences of the disease on the brain are required to understand the pathophysiological mechanisms having concurrent influences on the brain and the peripheral vasculature.

The rebirth of neuroscience in psychosomatic medicine, Part II: clinical applications and implications for research

During the second half of the last century, biopsychosocial research in psychosomatic medicine largely ignored the brain. Neuroscience has started to make a comeback in psychosomatic medicine research and promises to advance the field in important ways. In this paper we briefly review select brain imaging research findings in psychosomatic medicine in four key areas: cardiovascular regulation, visceral pain in the context of functional gastrointestinal disorders, acute and chronic somatic pain and placebo. In each area, there is a growing literature that is beginning to define a network of brain areas that participate in the functions in question. Evidence to date suggests that cortical and subcortical areas that are involved in emotion and emotion regulation play an important role in each domain. Neuroscientific research is therefore validating findings from previous psychosomatic research and has the potential to extend knowledge by delineating the biological mechanisms that link mind and body more completely and with greater specificity. We conclude with a discussion of the implications of this work for how research in psychosomatic medicine is conducted, the ways in which neuroscientific advances can lead to new clinical applications in psychosomatic contexts, the implications of this work for the field of medicine more generally, and the priorities for research in the next 5 to 10 years.

Parental assessments of internalizing and externalizing behavior and executive function in children with primary hypertension

OBJECTIVE

To determine the relations between hypertension and parental ratings of behavior and executive functions in children with primary hypertension and to examine the potential moderating influence of obesity.

STUDY DESIGN

Hypertensive and normotensive control groups were matched for age, sex, race, intelligence quotient, maternal education, household income, and obesity. Parents completed the Child Behavior Checklist to assess Internalizing and Externalizing problems and the Behavior Rating Inventory of Executive Function to assess behavioral correlates of executive function.

RESULTS

Thirty-two hypertensive subjects and 32 normotensive control subjects (aged 10 to 18 years) were enrolled. On the Child Behavior Checklist, hypertensives had higher Internalizing T-scores (53 vs 44.5, P = .02) with 37% falling within the clinically significant range vs 6% of control subjects (P = .005). Internalizing score increased with increasing body mass index percentile in hypertensive but not normotensive subjects. Hypertensives had worse Behavior Rating Inventory of Executive Function Global Executive Composite T-scores compared with control subjects (50 vs 43, P = .009).

CONCLUSIONS

Children with both hypertension and obesity demonstrate higher rates of clinically significant internalizing problems, and hypertensives (irrespective of obesity) demonstrate lower parental ratings of executive function compared with normotensive control subjects.

Vascular health risks and fMRI activation during a memory task in older adults

Vascular problems increase Alzheimer's disease (AD) risk, but the nature of this relationship remains unclear. Older adults having genetic risk for AD show regionally increased functional magnetic resonance imaging (fMRI) activity during memory, possibly representing compensation for a genetically induced neural deficit. We investigated whether vascular health risks, which similarly could lead to neuropsychological deficits, also showed increased fMRI activity during a memory task performed by 30 cognitively intact, primarily normotensive older adults (mean age=61). Vascular risk measures included systolic blood pressure (sBP), body mass index (BMI), and total cholesterol. Higher sBP and BMI (but not total cholesterol) were significantly correlated with increased activation in posterior cingulate cortex and frontal, temporal, and parietal regions. In posterior cingulate and parietal cortices, these relationships were evident even within sBP and BMI ranges considered normal, and were independent of hippocampal volume. Our results are similar to those in prior AD risk research, and suggest that fMRI reveals an abnormal response to cognitive processes in cognitively intact older adults with increased vascular risk.

Alcohol consumption and cerebral blood flow among older adults

A substantial epidemiological literature now supports the existence of a J or U-shaped association between alcohol consumption and a broad range cardiovascular health outcomes including stroke. Although it is well documented that alcoholics exhibit both global and regional cerebral hypoperfusion in the sober state, little is known regarding the effects of a broader range of alcohol consumption on cerebral blood flow (CBF). The present study employed positron emission tomography with H(2)(15)O to assess quantitative global and regional CBF in 86 participants (51 men and 35 women; mean age 60.1) as a function of self-reported weekly alcohol consumption (none, <1, 1 to <7, 7 to <15, and >15 drinks per week). Analyses controlling for age, gender, and vascular health (carotid intima-media thickness) revealed that, relative to the weighted population mean, global CBF was greater in the lightest alcohol consumption group (<1 per week) and lower in the heaviest (>15 per week). Effects did not vary across regions of interest. This report is the first to describe an inverted J-shaped relationship between alcohol consumption and CBF in the absence of stroke.

Reduced brain perfusion and cognitive performance due to constitutional hypotension

This review article includes a systematic evaluation of the empirical data concerning deficits in mental ability, brain perfusion, and cerebral functioning due to chronically low blood pressure. A number of studies have provided strong evidence for reduced cognitive performance in hypotension, particularly in the domains of attention and memory. EEG studies have demonstrated that the hypotension-related poorer mental ability is also reflected in diminished cortical activity. Contrary to convention, more recent research has suggested a deficient regulation of cerebral blood flow in persons with low blood pressure. In addition to reduced tonic brain perfusion, studies demonstrated insufficient adjustment of blood flow to cognitive requirements. Altogether, these findings suggest that more attention should be allocated to chronic hypotension in both research and clinical practice.

Long-term efficacy and safety of celecoxib in Alzheimer's disease

BACKGROUND/AIMS

Cyclooxygenase-2 (COX-2) may play an important role in the neuropathology of Alzheimer's disease (AD). The efficacy and safety of celecoxib (200 mg bid), a COX-2 selective inhibitor, were assessed in patients > or =50 years with established mild-to-moderate AD to determine whether treatment was effective in retarding deterioration of cognitive function.

METHODS

This was a 52-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study. The primary efficacy end points were the change from baseline to week 52 in the Alzheimer's Disease Assessment Scale-Cognitive Behavior (ADAS-cog) composite score and the week 52 Clinician's Interview-Based Impression of Change Plus (CIBIC+).

RESULTS

At 52 weeks, change in ADAS-cog scores from baseline was similar for placebo and celecoxib 200 mg bid groups (5.00 and 4.39, respectively). CIBIC+ scores were also similar (4.83 and 4.92). Two extension studies were conducted but were terminated early based on these efficacy results. Safety data from all 3 studies indicated that celecoxib was generally well-tolerated.

CONCLUSION

Celecoxib 200 mg bid did not slow the progression of AD in this study, and the occurrence of adverse events was as expected for an elderly population with a complex chronic medical condition.

Neuropsychological characteristics of adolescent boys differing in risk for high blood pressure

BACKGROUND

Individuals with established hypertension have been found to display deficits in a number of neuropsychological abilities. In general, these are probably due to structural changes in the brain produced by sustained high blood pressure. However, a potentially important line of research suggests that some of these deficits may extend to younger individuals with less severe elevations of blood pressure, perhaps even children, and thus be related more to risk for hypertension than hypertension per se.

PURPOSE

The objective was to examine the relationships between neuropsychological function and risk for hypertension in children.

METHODS

Measurements of blood pressure and parental history of hypertension were obtained in 88 French-Canadian 14-year-old boys and used to predict performance on a neuropsychological battery.

RESULTS

Boys at greater risk of hypertension by virtue of having a parental history of high blood pressure and normatively elevated systolic blood pressure had significantly lower scores on a verbal learning factor score compared to boys at lower risk. Boys with normatively elevated systolic blood pressure also had significantly lower scores on a spatial learning and memory factor score compared to boys with lower blood pressure. The results could not be attributed to differences in family socioeconomic status.

CONCLUSIONS

Using a younger sample than typically employed in the area, the results support previous suggestions that some of the neuropsychological characteristics displayed by hypertensive individuals may predate the development of clinically elevated blood pressure and could be associated with risk for the disorder.

A conceptual model of cognitive deficits in chronic heart failure

PURPOSE

To describe a conceptual model to guide studies of cognitive deficits among patients with heart failure.

ORGANIZING FRAMEWORK

The conceptual framework of cognitive deficits in chronic heart failure is based on theoretical and empirical literature about (a) the pathophysiology of heart failure, (b) the pathophysiology of cognitive deficits, and (c) health-related quality of life. Other variables that may cause or contribute to cognitive deficits include age, the relative contributions of multiple comorbid conditions, hypertension, and depressive symptoms. Covariates that might influence cognitive deficits (medications, gender, and education) are also included in the model. The most prominent cognitive deficits are believed to occur in domains of attention, working memory, memory, learning, executive function, and psychomotor speed. The main outcome variable is health-related quality of life, which is believed to be influenced by circulatory insufficiency and cognitive deficits.

CONCLUSIONS

The conceptual model described in this paper is a framework for testing cognitive deficits that occur in heart failure. After validation through empirical testing, the model may be useful in developing interventions for patients with heart failure whose care is complicated by cognitive deficits.

Essential hypotension is accompanied by deficits in attention and working memory

In the present study, the authors investigated the relationship between low blood pressure (BP) and attentional performance through the application of a multidimensional diagnostic approach. The authors compared 40 subjects with essential hypotension (mean systolic BP = 97.6 mmHg) with 40 normotensive controls (mean systolic BP = 124.1 mmHg) using 6 computer-based tasks measuring tonic and phasic alertness; selective, divided, and sustained attention; and working memory. To control for possible confounders, the authors used a test battery examining motor performance and a mood questionnaire. BP was monitored continuously during the entire experiment. Hypotensives showed prolonged execution times in each of the attentional tasks (p < .001). Moderately decreased accuracy was found in the tests assessing sustained attention (p = .059) and working memory (p = .012). Moreover hypotensives showed smaller elevations in BP during the execution of the cognitive tasks. This study is the first to demonstrate the relationship between BP and cognitive performance while controlling for motor function and mood.

Comparing extent of activation: a robust permutation approach

The number of contiguous voxels activated in a brain image can differ between groups or conditions even though the amplitude of activation does not markedly differ. Existing techniques test for differences in amplitude given that extent (number of contiguous voxels) exceeds some threshold. We present a technique that tests for differences in extent of activation given that amplitude of activation exceeds some threshold. The technique was motivated by apparent differences in extent of regional cerebral blood flow (rCBF) between hypertensive and normotensive participants performing cognitive tasks. These data are used to illustrate our test for extent of activation. We threshold the estimated parameter map for each subject, count the number of voxels exceeding the threshold over a defined region enclosing activated cortical area, and test the hypothesis of difference in the number of activated voxels between the two groups. Due to the large number of zeros resulting from the thresholding and the occurrence of extreme observations, we use a Robust permutation test [Lambert, D., 1985. Robust two-sample permutation tests. Ann. Stat., 13, 606-625], which is based on the sum of censored log-likelihood ratios. This statistic has desirable properties relative to the usual permutation test in contaminated distributions, i.e., idealized histogram with outliers, and provides an appropriate and robust test of extent of activation between conditions or groups.

Regional cerebral blood flow correlates with heart period and high-frequency heart period variability during working-memory tasks: Implications for the cortical and subcortical regulation of cardiac autonomic activity

The aim of the present study was to characterize the functional relationships between behaviorally evoked regional brain activation and cardiac autonomic activity in humans. Concurrent estimates of regional cerebral blood flow (rCBF; obtained by positron emission tomography), heart period, and high-frequency heart period variability (HF-HPV; an indicator of cardiac parasympathetic activity) were examined in 93 adults (aged 50-70 years) who performed a series of increasingly difficult working-memory tasks. Increased task difficulty resulted in decreased heart period (indicating cardioacceleration) and decreased HF-HPV (indicating decreased cardiac parasympathetic activity). Task-induced decreases in heart period and HF-HPV were associated with concurrent increases and decreases in rCBF to cortical and subcortical brain regions that are speculated to regulate cardiac autonomic activity during behavioral processes: the medial-prefrontal, insular, and anterior cingulate cortices, the amygdala-hippocampal complex, and the cerebellum. These findings replicate and extend a small number of functional neuroimaging studies that suggest an important role for both cortical and subcortical brain systems in human cardiac autonomic regulation.